这项研究是通过由科学、信息和通信技术和未来规划部 (NRF-2018R1A2A1A05019892) 资助的韩国国家研究基金会 (NRF) 和植物分子育种中心的赠款来支持的。PMBC) 下一代 Biogreen 21 农村发展管理计划 (PJ013201) 向 EP。我们感谢国家环境管理仪器中心的成像中心, 为拍摄提供了共焦显微镜。

注: 所有步骤均在室温下执行, 除非另有说明。
1. 植物材料的制备 (4 周)
<ol><li>为benthamiana工厂准备<ol>
<li>在每个花盆的土面上播种benthamiana的2种子, 用塑料圆顶覆盖托盘, 并允许种子在25摄氏度、60% 湿度生长室中发芽, 其温度为16/8 小时/暗光周期。</li>
		<li>两周后, 挑选出并丢弃每壶中最小的幼苗, 并继续种植在相同的生长条件下, 在1.1.1 发芽的应用。每两天增加1升的水每托盘。 注意: 植物的生长条件可能在实验室中有所不同。因此, 遵循常规浇水协议, 种植植物在一个健康的条件。</li>
		<li>在一周内, 将植物转移到一个新的托盘, 并安排他们有足够的空间, 以进一步增长。在步骤1.1.1 中描述的条件下, 保持植物的生长, 直到它们准备在4周的年龄内渗入。 注: 植物生长可能会因不同实验室的生长情况而异。通常, 我们发现, 4 周大的benthamiana植物大约有六叶。</li>
	</ol>
</li>
	<li>对南芥转基因植物的制备<ol>
<li>请参阅材料表并订购转基因的拟南芥种子。</li>
		<li>在1毫升蒸馏水中浸泡 ~ 50-100 转基因的拟南芥种子, 并将它们贮存在4摄氏度, 在黑暗中保存3天, 以同步发芽的开始。</li>
		<li>在插头厂托盘的土壤表面播种 2-3 种子, 用塑料圆顶盖上托盘。允许种子发芽23摄氏度, 60% 湿度, 10/14 小时光/暗周期。 注: 种子应纯合体。然而, 我们建议重申的存在, 转基因在批。在这种情况下, 用70% 乙醇洗涤种子, 2 分钟, 50% 漂白剂 (约2% 次氯酸盐), 含 0.05% X-100 的5分钟. 跟随通过洗涤 5-6 次以无菌双重蒸馏水 (ddH2O)。灭菌后, 分层在4摄氏度3天, 并将其印在植物萌发培养基上, 含潮霉素 B 的25µg/升, 以选择转基因植物。</li>
		<li>一周后, 每个插头只留一株植物, 并继续生长在相同的生长条件下, 用于步1.2.3 的植物。 注: 四周大的植物用于野火感染。水植物每隔一天保持植物的健康。</li>
	</ol>
</li>
</ol>2. 准备假单胞菌文化 (~ 1 周)
<ol><li>铜绿假单胞菌转化质粒的构建<ol>
<li>请参阅材料表, 并订购 T3SS-based 效应传递系统向量25所需的向量。</li>
		<li>使用站点特定的重组克隆25将感兴趣的效应基因插入效应传递向量中。 注: 在监测全长效应蛋白的亚细胞定位时, 将全长基因 pBK-GW-1-2 或 pBG-GW-1-2。还可以选择含有 2x sfGFP11 的 pBK-GW-1-4 或 pBG-GW-1-4, 以增加荧光信号。对于缺乏信号肽的部分效应器, 使用 pBK-GW-2-2 或 pBK-GW-2-4。有关效应传递向量25的详细信息, 请参阅公园et .。</li>
	</ol>
</li>
	<li>将带有效应器的质粒转换为野火pv, 并将其与 sfGFP11 标记融合在一起。西红柿(Pst)CUCPB5500 使用标准电穿孔29。 注意: 如果需要, 可以使用其他铜绿假单胞菌。sfGFP11 标记系统是为范围很广的向量30构造的, 并且该效应器的基因表达式由 AvrRpm1 启动子来调节, 它与如假单胞菌荧光(伊桑)31之间的比较。</li>
	<li>将转化后的细菌细胞轻轻地散布在含有100µg/毫升利福平和25µg/毫升卡那霉素或25µg/毫升庆大霉素的王 B 琼脂板表面。孵育28°c 2 天。</li>
	<li>接种一个殖民地入国王的 B 液体媒介以适当为载体使用的抗生素, 并且在28°c 隔夜生长细胞与震动在200转每分钟。</li>
	<li>做甘油的存货。将蒸压甘油添加到最终浓度为 50%, 并贮存在-80 摄氏度。</li>
</ol>3. 在benthamiana (4 天) 中, 以细胞器为目标的 sfGFP1-10选择的瞬时表达式
<ol><li>农杆菌区域性的制备<ol>
<li>订购所需的细胞器目标 sfGFP1-10 可选质粒 (参见材料表)。</li>
		<li>将质粒转换成根癌农杆菌应变 GV3101 细胞32。在 Luria-Bertani (磅) 琼脂培养基上生长细胞, 辅以50µg/毫升卡那霉素和50µg/毫升利福平28摄氏度, 2 天。</li>
		<li>从单一菌落的 LB 琼脂培养基, 接种细胞成5毫升的液体 LB 培养基补充50µg/毫升卡那霉素和50µg/毫升利福平。在28摄氏度的时候以200转每分钟的抖动来生长细胞。</li>
		<li>以 3000 x g 为10分钟, 以离心的方法收割细胞, 然后从上清介质中并用重悬, 并在1毫升的新入渗缓冲液中注入颗粒。</li>
		<li>通过获取 600 nm (Abs 600 nm) 的吸收光密度 (OD) 值来测量农杆菌的数量。将细菌的 OD600调整为 0.5, 并使用浸润缓冲。 注: 1 毫升的悬浮液足以渗入两个斑点。</li>
		<li>在 1-5 小时的渗透前, 在室温下将培养基留在一个柔和的摇杆上。</li>
		<li>把一个洞戳进叶子的中心, 然后用10µL 的尖端渗入。使用1毫升无针注射器渗入农杆菌悬浮液。仔细和缓慢地注入约500µL 的悬浮液准备从步骤3.1.5 到叶正面通过注射器。重复对至少三种不同植物的渗透实验复制。 注意: 出于健康和安全的原因, 在渗透过程中应佩戴眼部防护。</li>
		<li>擦掉叶子上残留的细菌悬浮液, 标记浸润区域的边界。</li>
		<li>保持渗透植物在相同的生长条件下, 用于步骤 1.1.1 2 天。</li>
	</ol>
</li>
</ol>4. 接种假单胞菌(4 天)
<ol><li>将从步骤2.5 中的甘油库存中的已转换的铜绿假单胞菌与相应的抗生素在28摄氏度处连续2天进行条纹。 注意:铜绿假单胞菌的健康非常关键。如果殖民地不形成好, 再次条纹细胞或传播的细胞在国王的液体媒体之前, 继续进行。</li>
	<li>在28摄氏度的甘露醇-谷氨酸 (MG) 液体介质中接种一 loopful 的铜绿假单胞菌细胞, 一夜之间以200转每分钟的抖动。</li>
	<li>以 3000 x g 为10分钟, 以离心的方法收割细胞. 倒入上清介质, 在10毫米氯化镁2中并用重悬颗粒, 并将 N . benthamiana 叶和 1 (10 x7 0.002) 的OD 600 调整为 0.02 (1 x10 6 cfu/毫升);cfu/mL) 为拟南芥留下.
</li>
	<li>对于benthamiana, 将铜绿假单胞内的悬浮液渗透到叶子的区域, 其中农杆菌携带 sfGFP1-10选择构造被渗透2天前 (如步骤 3.1.7)。对于 sfGFP1-10选择转基因拟南芥, 将假单胞菌的悬浮液渗透到两个4周长的短日生长的叶子中。 注意: 实验复制需要至少三株植物。</li>
</ol>5. 通过共聚焦显微镜观察 sfGFP 信号 (1 天)
<ol><li>从假单胞菌接种的叶子中剪下叶盘。在铜绿假单渗入后的特定时间点, 图像两个2厘米2叶盘从单一植物使用激光扫描共焦系统与 40 x/1.2 NA c 复消色差水浸泡目标或 63 x/0.8 na c-复消色差油浸泡目的。为了避免被伤致死的细胞, 观察细胞远离浸润孔。</li>
	<li>开始观察在低功率设置的 488 nm 氩激光。增加激光功率以检测 sfGFP。 注: 我们通常使用 2-15% 的激光强度来检测荧光信号。但是, 激光功率和检测设置应根据用户的显微系统进行调整。在这里, 发射过滤器被设置为 520-550 nm。死细胞通常在488纳米激光激发下发出自动荧光。因此, 作为一个负控制, 在相同的观测条件下, 没有 sfGFP11 标记的同样的效应器应该被渗透和观察。此外, 高激光激发能诱发叶绿素自发荧光。因此, 用控制植物细胞调节激光强度, 不诱导叶绿素自发荧光。<ol>
<li>对于细胞壁的 counterstaining, 在观察前 5-10 分钟内浸润20毫米碘碘化物 (PI) 到叶盘中。</li>
		<li>对于细胞核染色, 将叶盘浸入0.1% 多聚甲醛5分钟, 然后用水冲洗。然后, 在显微镜观察之前, 将10毫米 PI 渗透到叶盘中 5-10 分钟。重复实验至少三次。 注意: 这一步并不重要, 但有助于定义在等离子膜或原子核上的效应器定位。如果感兴趣的效应器显示他们在特定的细胞器中的定位, 使用一个标记为给定的细胞, 以确认该效应器的本地化。</li>
	</ol>
</li>
</ol>

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H., Eitas, T. K., Dangl, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+intracellular+innate+immune+receptor+Resistance+to+Pseudomonas+syringae+pv.+maculicola+1+(RPM1)+is+activated+at,+and+functions+on,+the+plasma+membrane.">Plant intracellular innate immune receptor Resistance to Pseudomonas syringae pv. maculicola 1 (RPM1) is activated at, and functions on, the plasma membrane.</a> Proc Natl Acad Sci U S A. 108 (18), 7619-7624 (2011).</li><li>Leonetti, M. D., Sekine, S., Kamiyama, D., Weissman, J. 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作者没有披露的利益冲突。

这里描述的协议用于监测细菌 T3SS 注射的效应蛋白在感染时对宿主植物细胞的准确定位。以前, 分离 GFP 系统被用来作为一个工具, 研究哺乳动物蛋白的亚细胞定位23,36,沙门氏菌T3E 本地化, 和农杆菌VirE2 交付通过 T4SS 到植物细胞37。为了在植物细胞中应用这个系统, 以前的研究使用了一种转基因玉米植株, 组成性表达 GFP1-10 和转基因真菌,黑穗病玉米, 表达 GFP11-tagged 效应蛋白。然而, 玉米-玉米系统还没有成功, 因为移位效应蛋白的表达水平较弱, 背景自发荧光的高水平阻碍了对重组 GFP 信号38的检测。为了解决这个问题, 我们使用了一个 sfGFP1-10 变体, sfGFP1-10 可选, 大大提高了溶解度和荧光强度21,22。
尽管分裂 sfGFP 系统具有优势, 但对效应器定位和动力学的研究也存在一定的局限性。首先, 观测到的重组 sfGFP 荧光信号相对较弱。这可能是由于从野火直接传递的少量效应分子。使用 multimerizing sfGFP11 标记可以改进此微弱信号。携带 2x sfGFP11 标记的矢量也可从材料表中列出的源中获得。其次, 胞浆 sfGFP1-10 可选未能用 sfGFP11 目标为高尔基、ER 和质25进行重组。线粒体靶向 sfGFP11 和胞浆 sfGFP1-10 的协同表达可选导致 mislocalization 细胞质和核25的重新构成 sfGFP。因此, 应通过应用适当的细胞器目标 sfGFP1-10 可选来重新验证感兴趣的效应器的本地化。当在表示胞浆 sfGFP1-10选择的受感染细胞中未检测到任何 GFP 信号时, 建议使用N. 葛根表示高尔基、ER 和质目标 sfGFP1-10选择或使用相应细胞器目标sfGFP1-10选择转基因拟南芥25。
该方法表明, 利用分裂荧光蛋白系统作为一个有用的工具, 以检查的时间和空间动力学的效应在宿主植物25。未来的研究将集中在单分子成像的进展, 这可能使详细研究的动态, 等离子膜局部效应。此外, 使用细菌系统进行分泌物检测可能是研究真菌效应的局部化的有益选择;它防止在真菌穿透部位聚集的效应和高荧光。
应注意的是, 该方法存在一些关键点。首先, 植物材料和细菌应该是健康和新鲜的。为确保效应信号的可视化, 应强烈表达来自植物的 sfGFP1-10选择和从假单胞sfGFP11。因此, 在最佳生长条件下种植植物, 并保护它们免受诸如害虫等环境胁迫是很重要的。我们还建议, 所有用于渗透的细菌都是从2天生长的细胞, 在琼脂板块, 而不是从甘油的股票。其次, 在benthamiana中的瞬态表达式中, 对于每个细胞器标记蛋白而言, 细胞型靶向 sfGFP1-10选择的成熟所需的时间长短可能会有所不同。例如, PM-sfGFP1-10选择的成熟度在渗透后需要超过48小时。最后, 重组后的 sfGFP 信号的时间点和表达水平取决于优化某些实验条件所需的效应蛋白的类型。

植物是一种无梗的有机体, 在整个生命周期中遇到许多入侵的病原体, 包括细菌、真菌、病毒、昆虫和线虫。在 phytopathogens 中, 革兰阴性细菌病原体, 如铜绿假单胞菌和青, 通过进入伤口或自然开口, 如气孔和具1, 感染寄主植物。为了成功地将寄主植物殖民化, 细菌病原体已经进化形成了各种致病因子2。当细菌侵入寄主植物时, 它们会注射一系列的毒力蛋白--被称为效应者--直接进入植物细胞, 以促进其致病性。这些效应抑制或调节植物先天免疫, 并操纵宿主细胞过程, 导致细菌生存3。
致病细菌主要使用 T3SS 将效应蛋白直接传递到宿主细胞中4。T3SS 类似于一个分子注射器, 其针状通道连接从支架蛋白结构横跨内部和外部细菌膜到宿主细胞的注射点5。这种 T3SS-mediated 效应器 (T3E) 分泌机制在植物的各种革兰氏阴性细菌病原体以及人类中都保存良好。一个代表性植物病原体,野火pv。西红柿DC3000 hrcC变种通常有缺陷的 T3SS, 限制了植物的生长, 可能是由于这个突变体无法完全抑制植物免疫 (通过注射效应蛋白)6。在转移到宿主细胞后, 效应靶针对宿主细胞系统中重要的各种宿主蛋白, 包括植物防御反应、基因转录、细胞死亡、蛋白酶体、囊泡贩运和激素通路7,8,9,10. 因此, 跟踪宿主细胞中效应蛋白的细胞定位是了解它们在调节植物免疫力方面的作用的一个很有吸引力的目标。
大多数 T3Es 的定位研究都采用了农杆菌-介导的大荧光蛋白在寄主植物9中的过度表达。然而, 其他物种引入的基因的异种表达方法已被证明是错误本地化的, 或者偶尔不起作用的11,12,13。此外, 一些研究显示, 细菌效应在宿主细胞中进行了适当的靶向定位14,15,16,17。因此, 瞬时表达的效应在植物细胞的细胞质可能不是功能上或数量相同的效应者, 由 T3SS 提供的病原体感染18。此外, 大荧光标记与效应蛋白的融合可能会扰乱适当的效应传递和可视化18,19。因此, 这些检测 T3E 功能的方法可能无法充分反映 T3SS-secreted 效应的本土化。
绿色荧光蛋白 (GFP) 由一个11股的β桶组成, 其中包含一个包括生色20的中心链。金都et报道了一个新的分裂-GFP 系统, 由一个小组成部分 (gfp β链 11;GFP11) 和一个大的互补片段 (GFP β链 1-10;GFP1-10)21。片段不荧光自己, 但荧光后, 他们的自我联想, 当两个片断是在密切接近。对于蛋白质折叠效率的优化, gfp 的鲁棒折叠变体,即, sfGFP 和 sfGFP选择, 随后为分割的 gfp 系统20,21,22而开发。最近, sfGFP1-10 可选-sfYFP1-10选择和 sfCFP1-10选择的单个氨基酸突变变种, 可以用 sfGFP11 片段进行重建, 并分别显示黄色和青色荧光, 生成23.此外, sfCherry 是 mCherry 的导数, 可以以与 sfGFP23相同的方式拆分为 sfCherry1-10 和 sfCherry11 片段。
该系统已经适应了标签和跟踪 T3SS 在 HeLa 细胞感染期间使用的效应器从沙门氏菌24.然而, 它以前未被优化为寄主植物细菌病原体系统。最近, 我们优化了基于改进的 sfGFP1-10 可选的分割 GFP 系统, 以监视从野火发送到植物单元25的 T3Es 的亚细胞定位。为了促进 T3Es 对不同亚细胞间的定位研究, 一组转基因的拟南芥植物在不同的亚细胞间隔内生成 sfGFP1-10 可选25. 此外, 携带各种细胞器靶向的 sfGFP1-10 的质粒选择用于农杆菌介导的瞬态过度表达和 T3SS-based 效应传递的 sfGFP11-tagged 向量也产生。各种转基因的拟南芥线和质粒来表达 T3Es 的种子, 可以从材料表26,27中提到的来源获得。
在下面的协议中, 我们描述了一个优化系统, 以监测由细菌在宿主细胞中使用分裂 sfGFP 系统传递的效应器的动力学。表达 sfGFP1-10选择的植物感染转基因假单胞菌携带重组 sfGFP11 质粒导致 sfGFP11-tagged 效应器从假单胞菌交付宿主细胞。因此, 这些蛋白质被重组, 并植物常常将到特定的效应靶室 (s)。假单胞野火pv。西红柿CUCPB5500 菌株, 其中18个效应被删除, 使用, 因为这种菌株显示低或没有细胞死亡, 在A. 南芥和N. benthamianas28。然而, 这里描述的所有材料和步骤可以被替换或修改, 以适应分裂 sfGFP 系统的调查其他生物问题或优化在给定的实验室条件。

<table>
	<tbody>
		<tr>
			<td>Arabidopsis transgenic lines</td>
			<td></td>
			<td></td>
			<td>Park, E., Lee, H. Y., Woo, J., Choi, D. &#38; Dinesh-Kumar, S. P. Spatiotemporal Monitoring of Pseudomonas syringae Effectors via Type III Secretion Using Split Fluorescent Protein Fragments. Plant Cell. 29 (7), 1571-1584 (2017)</td>
		</tr>
		<tr>
			<td>CYTO-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69831</td>
			<td></td>
		</tr>
		<tr>
			<td>NU-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69832</td>
			<td></td>
		</tr>
		<tr>
			<td>PT-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69833</td>
			<td></td>
		</tr>
		<tr>
			<td>MT-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69834</td>
			<td></td>
		</tr>
		<tr>
			<td>PX-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69835</td>
			<td></td>
		</tr>
		<tr>
			<td>ER-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69836</td>
			<td></td>
		</tr>
		<tr>
			<td>GO-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69837</td>
			<td></td>
		</tr>
		<tr>
			<td>PM-sfGFP1-10</td>
			<td>ABRC</td>
			<td>CS69838</td>
			<td></td>
		</tr>
		<tr>
			<td>Organelle-targeted sfGFP1-10OPT plasmid</td>
			<td></td>
			<td></td>
			<td>Park, E., Lee, H. Y., Woo, J., Choi, D. &#38; Dinesh-Kumar, S. P. Spatiotemporal Monitoring of Pseudomonas syringae Effectors via Type III Secretion Using Split Fluorescent Protein Fragments. Plant Cell. 29 (7), 1571-1584 (2017)</td>
		</tr>
		<tr>
			<td>CYTO-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97387</td>
			<td></td>
		</tr>
		<tr>
			<td>NU-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97388</td>
			<td></td>
		</tr>
		<tr>
			<td>PT-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97389</td>
			<td></td>
		</tr>
		<tr>
			<td>MT-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97390</td>
			<td></td>
		</tr>
		<tr>
			<td>PX-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97391</td>
			<td></td>
		</tr>
		<tr>
			<td>ER-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97392</td>
			<td></td>
		</tr>
		<tr>
			<td>GO-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97393</td>
			<td></td>
		</tr>
		<tr>
			<td>PM-sfGFP1-10</td>
			<td>Addgene</td>
			<td>97394</td>
			<td></td>
		</tr>
		<tr>
			<td>ER-sfCherry1-10</td>
			<td>Addgene</td>
			<td>97403</td>
			<td></td>
		</tr>
		<tr>
			<td>ER-sfYFP1-10</td>
			<td>Addgene</td>
			<td>97404</td>
			<td></td>
		</tr>
		<tr>
			<td>CYTO-sfCFP1-10</td>
			<td>Addgene</td>
			<td>97405</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="3">sfGFP11-tagged Gateway compatible vector for T3SS-based effector delivery system</td>
			<td>Park, E., Lee, H. Y., Woo, J., Choi, D. &#38; Dinesh-Kumar, S. P. Spatiotemporal Monitoring of Pseudomonas syringae Effectors via Type III Secretion Using Split Fluorescent Protein Fragments. Plant Cell. 29 (7), 1571-1584 (2017)</td>
		</tr>
		<tr>
			<td>pBK-GW-1-2</td>
			<td>Addgene</td>
			<td>98250</td>
			<td>pAvrRpm1:GW:HA-sfGFP11:AvrRpm1t; Resistant to Kanamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBK-GW-1-4</td>
			<td>Addgene</td>
			<td>98251</td>
			<td>pAvrRpm1:GW:HA-2xsfGFP11:AvrRpm1t; Resistant to Kanamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBK-GW-2-2</td>
			<td>Addgene</td>
			<td>98252</td>
			<td>pAvrRpm1:AvrRPM1sp:GW:HA-sfGFP11:AvrRpm1t; Resistant to Kanamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBK-GW-2-4</td>
			<td>Addgene</td>
			<td>98253</td>
			<td>pAvrRpm1:AvrRPM1sp:GW:HA-2xsfGFP11:AvrRpm1t; Resistant to Kanamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBG-GW-1-2</td>
			<td>Addgene</td>
			<td>98254</td>
			<td>pAvrRpm1:GW:HA-sfGFP11:AvrRpm1t; Resistant to Gentamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBG-GW-1-4</td>
			<td>Addgene</td>
			<td>98255</td>
			<td>pAvrRpm1:GW:HA-2xsfGFP11:AvrRpm1t; Resistant to Gentamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBG-GW-2-2</td>
			<td>Addgene</td>
			<td>98256</td>
			<td>pAvrRpm1:AvrRPM1sp:GW:HA-sfGFP11:AvrRpm1t; Resistant to Gentamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>pBG-GW-2-4</td>
			<td>Addgene</td>
			<td>98257</td>
			<td>pAvrRpm1:AvrRPM1sp:GW:HA-2xsfGFP11:AvrRpm1t; Resistant to Gentamycin (25 ug/ml)</td>
		</tr>
		<tr>
			<td>Bacterial strains</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Agrobacterium tumefaciens GV3101</td>
			<td></td>
			<td></td>
			<td>Csaba Koncz and Jeff Schell, The promoter of TL-DNA gene 5 controls the tissue-specific expression of chimaeric genes carried by a novel type of Agrobacterium binary vector. Mol Gen Genet. 204,383-396 (1986); Resistant to gentamycin (50 ug/ml) and rifampicin (50 ug/ml)</td>
		</tr>
		<tr>
			<td>Pseudomonas syringae pv. Tomato CUCPB5500</td>
			<td></td>
			<td></td>
			<td>Kvitko, B. H. et al. Deletions in the repertoire of Pseudomonas syringae pv. tomato DC3000 type III secretion effector genes reveal functional overlap among effectors. PLoS Pathog. 5 (4) (2009).; Resistant to rifampicin (100 ug/ml)</td>
		</tr>
		<tr>
			<td>Media components</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plant germination media</td>
			<td></td>
			<td></td>
			<td>Add 2.165g/L Murashige &#38; Skoog powder, 10 g/L sucrose to water. Adjust to pH 5.8 and add 2.2 g/L phytagel. Autocalve.</td>
		</tr>
		<tr>
			<td>Murashige &#38; Skoog medium including vitamins</td>
			<td>Duchefa Biochemie</td>
			<td>M0222</td>
			<td>Store at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Duchefa Biochemie</td>
			<td>S0809</td>
			<td></td>
		</tr>
		<tr>
			<td>Phytagel</td>
			<td>Sigma-Aldrich</td>
			<td>P8169</td>
			<td></td>
		</tr>
		<tr>
			<td>LB media</td>
			<td></td>
			<td></td>
			<td>Add 10 g/L tryptone, 5 g/L yeast extract, 10 g/L NaCl to water. For solid media, add 15 g/L micro agar. Autoclave.&#160; Allow solution to cool to 55 &#176;C, and add antibiotic if needed.</td>
		</tr>
		<tr>
			<td>Tryptone</td>
			<td>BD Bioscience</td>
			<td>211705</td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast extract</td>
			<td>BD Bioscience</td>
			<td>212750</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Duchefa Biochemie</td>
			<td>S0520</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro agar</td>
			<td>Duchefa Biochemie</td>
			<td>M1002</td>
			<td></td>
		</tr>
		<tr>
			<td>King&#39;s B media</td>
			<td></td>
			<td></td>
			<td>10 g/L protease peptone #2, 1.5 g/L anhydrous K2HPO4, 15 g/L of agar to water. Autoclave. Cool down to 55 &#176;C and add sterile 15 ml/L glycerol, 5 ml/L MgSO4 to the medium. Add antibiotics if needed.</td>
		</tr>
		<tr>
			<td>Proteose peptone</td>
			<td>BD Bioscience</td>
			<td>212120</td>
			<td></td>
		</tr>
		<tr>
			<td>Anhydrous K2HPO4</td>
			<td>Sigma-Aldrich</td>
			<td>1551128 USP</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Duchefa Biochemie</td>
			<td>G1345</td>
			<td></td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Sigma-Aldrich</td>
			<td>M7506</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto Agar</td>
			<td>BD Bioscience</td>
			<td>214010</td>
			<td></td>
		</tr>
		<tr>
			<td>Mannitol-Glutamate (MG) liquid media </td>
			<td></td>
			<td></td>
			<td>Add 10 g/L of mannitol, 2 g/L of L-glutamic acid, 0.5 g/L of KH2PO4, 0.2 g/L of NaCl, and 0.2 g/L of MgSO4 to water. Adjust to pH 7</td>
		</tr>
		<tr>
			<td>Mannitol</td>
			<td>Duchefa Biochemie</td>
			<td>M0803</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamic acid</td>
			<td>Duchefa Biochemie</td>
			<td>G0707</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Sigma-Aldrich</td>
			<td>NIST200B</td>
			<td></td>
		</tr>
		<tr>
			<td>Infiltration buffer</td>
			<td></td>
			<td></td>
			<td>10 mM MES (2-(N-morpholino)-ethane sulfonic acid), 10 mM MgCl2, 150 &#181;M acetosyringone. pH 5.6; Prepare a fresh buffer before use.</td>
		</tr>
		<tr>
			<td>MES</td>
			<td>Duchefa Biochemie</td>
			<td>M1503</td>
			<td>Prepare 100 mM (pH 5.6) stock in water. Filter sterilize.</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>M8266</td>
			<td>Prepare 100 mM stock in water. Autoclave.</td>
		</tr>
		<tr>
			<td>Acetosyringone</td>
			<td>Sigma-Aldrich</td>
			<td>D134406</td>
			<td>Prepare 150 mM stock in DMSO.</td>
		</tr>
		<tr>
			<td>Confocal microscope equipments/materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>710 laser scanning confocal system</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Axio observer Z1 inverted microscope</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Propidium iodide</td>
			<td>ThermoFisher</td>
			<td>P1304MP</td>
			<td></td>
		</tr>
	</tbody>
</table>

split green fluorescent protein system to visualize effectors delivered from bacteria during infection

细菌是各种植物病害中最重要的致病因子之一, 它将一组效应蛋白分泌到宿主植物细胞中, 破坏植物的免疫系统。在感染期间细胞质效应通过 III. 型分泌系统 (T3SS) 传递给宿主细胞质。传递到植物细胞后, 效应器 (s) 靶向特定的隔间, 调节宿主细胞的过程以生存和复制病原体。虽然对宿主细胞中效应蛋白的亚型定位进行了研究, 以了解其在致病性中的作用, 利用荧光蛋白, 直接从细菌中注射的效应研究由于 T3SS 和荧光蛋白之间的不相容性而受到了挑战。
在这里, 我们描述了我们最近的方法, 优化分裂 superfolder 绿色荧光蛋白系统 (sfGFP选择), 以可视化的效应传递通过细菌 T3SS 在宿主细胞。通过 T3SS 分泌的 sfGFP 的 sfGFP11 (11th β链) 可以与特定的细胞器 (sfGFP1-10 可选(1-10 β链 sfGFP) 一起组装, 从而导致现场的荧光发射.该协议提供了一个程序, 以可视化重组 sfGFP 荧光信号的效应蛋白从假单胞菌野火在一个特定的细胞器在拟南芥和烟草 benthamiana植物。

GFP 的β桶结构由十一β链组成, 可分为两个片段, 1-10th链 (GFP1-10 可选) 和 11th (GFP11) 链。尽管两个碎片本身都不是荧光的, 但自组装 sfGFP 可以在接近接近度 (图 1A) 存在时发出荧光。在该系统中, sfGFP1-10 "选择"-表示拟南芥或N. benthamiana植物接种了假单胞菌携带一个 sfGFP11 标记的效应器。由铜绿假单胞传递到宿主单元格细胞质中的 sfGFP11 标记的效应器被重组为细胞质中表示的 sfGFP1-10 可选, 然后将植物常常将组合到目标隔间(图 1B)。图 2表示从植物材料的制备和Pst到植物细胞中荧光信号检测的整个过程。
作为我们的方法的一个例子, 我们使用了野火效应蛋白, AvrB, 它被传递到宿主植物细胞在感染期间彻底 T3SS。在拟南芥中, AvrB 由相应的抗性蛋白 RPM1 识别, 并触发免疫应答, 包括超敏细胞死亡33。在前一项研究中, GFP 报告和生化检测显示, AvrB 和 RPM1 在植物细胞的等离子膜 (33,34,35) 中被本地化。要使用我们的方法检查 AvrB 的本地化,农杆菌窝藏细胞 sfGFP1-10 可选基因已渗入benthamiana。两天后, AvrB-sfGFP11-transformed铜绿假单胞菌细胞接种到了农杆菌浸润区。在包含 AvrB-sfGFP11 的等离子膜 (图 3B) 的Pst CUCPB5500 中观察到补充的 sfGFP 荧光信号。相比之下, 通过携带本机 AvrB 的Pst (图 3A), 在受感染的单元格中未发现任何信号。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57719/57719fig1.jpg"> 图1。优化的分离 GFP 系统.(A) GFP 的β桶结构由十一β链组成, 可分为1-10 个th β链 (GFP1-10) 和 11th β链 (GFP11)。(B) 在此方法中, sfGFP1-10 可选片段在植物细胞中表达, 而 sfGFP11 链被融合到 AvrB 并转化为假单胞菌。只有含有 sfGFP11 的铜绿假单胞病毒感染的植物细胞才会显示 sfGFP 荧光 (其中的效应本地化)。<a href="/files/ftp_upload/57719/57719fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57719/57719fig2.jpg"> 图2。过程概述.转基因拟南芥或 sfGFP1-10选择浸润N. benthamiana植物感染了Pst CUCPB5500 携带 sfGFP11-tagged 效应器通过注射器浸润。通过在效应器定位现场的共焦显微系统, 可以检测组装 sfGFP 的荧光。<a href="/files/ftp_upload/57719/57719fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57719/57719fig3.jpg"> 图3。AvrB-sfGFP 检测N. benthamiana在感染后留下3小时.在 N. benthamiana的 5th或6叶上浸润了一个 sfGFP11-tagged AvrB 基因的Pst CUCPB5500, 这是由农杆菌在2天前携带 sfGFP1-10选择的。细胞壁被碘碘化物染色。虽然表达 sfGFP1-10 "选择" 的单元格仅 AvrB, 但不显示任何荧光信号 (A)。在3小时后浸润 (B) 中含有 AvrB-sfGFP11 基因的Pst观察到感染细胞中的 GFP 信号 (黄色箭头)。此结果表示只有 AvrB-sfGFP11, 而不是 AvrB, 在细胞质 sfGFP1-10 可选的情况下重组, 然后组装的 sfGFP 移位到等离子膜上。洋红伪色代表细胞壁和叶绿素自发荧光。绿色代表了组装的 sfGFP 荧光。刻度条 = 40 µm.<a href="/files/ftp_upload/57719/57719fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Split Green Fluorescent Protein System to Visualize Effectors Delivered from Bacteria During Infection at JoVE.com

Split Green Fluorescent Protein System to Visualize Effectors Delivered from Bacteria During Infection

分离绿色荧光蛋白系统可视化细菌在感染过程中传递的效应

以荧光蛋白为基础的方法来监测细菌分泌到宿主细胞中的效应, 这是很有挑战性的。这是由于荧光蛋白与 III. 型分泌系统之间的不相容。在这里, 一个优化的分裂 superfolder GFP 系统是用来可视化的效应, 细菌分泌的宿主植物细胞。

Bacteria, one of the most important causative agents of various plant diseases, secrete a set of effector proteins into the host plant cell to subvert the ...

split-green-fluorescent-protein-system-to-visualize-effectors

Universidad San Sebastian

Research

JoVE Journal

Biology

10.3K 次观看.  Seoul National University. 以荧光蛋白为基础的方法来监测细菌分泌到宿主细胞中的效应, 这是很有挑战性的。这是由于荧光蛋白与 III. 型分泌系统之间的不相容。在这里, 一个优化的分裂 superfolder GFP 系统是用来可视化的效应, 细菌分泌的宿主植物细胞。

视频: Split Green Fluorescent Protein System to Visualize Effectors Delivered from Bacteria During Infection

Primer Extension Capture: Targeted Sequence Retrieval from Heavily Degraded DNA Sources

We present a method of targeted DNA sequence retrieval from DNA sources which are heavily degraded and contaminated with microbial DNA, as is typical of ancient bones. The method greatly reduces sample destruction and sequencing demands relative to direct PCR or shotgun sequencing approaches. We used this method to reconstruct the complete mitochondrial DNA (mtDNA) genomes of five Neandertals from across their geographic range. The mtDNA genetic diversity of the late Neandertals was approximately three times lower than that of contemporary modern humans. Together with analyses of mtDNA protein evolution, these data suggest that the long-term effective population size of Neandertals was smaller than that of modern humans and extant great apes.

We present a method of targeted ancient DNA sequence retrieval, which we used to reconstruct the complete mitochondrial genomes of five Neandertal individuals. Comparison of these sequences with present day humans suggests that Neandertals had a long term low effective population size.

引物延伸捕获：从严重退化的DNA来源有针对性的顺序检索

We present a method of targeted DNA sequence retrieval from DNA sources which are heavily degraded and contaminated with microbial DNA, as is typical of ...

科研

生物学

Split-Ubiquitin Based Membrane Yeast Two-Hybrid (MYTH) System: A Powerful Tool For Identifying Protein-Protein Interactions

The fundamental biological and clinical importance of integral membrane proteins prompted the development of a yeast-based system for the high-throughput identification of protein-protein interactions (PPI) for full-length transmembrane proteins. To this end, our lab developed the split-ubiquitin based Membrane Yeast Two-Hybrid (MYTH) system. This technology allows for the sensitive detection of transient and stable protein interactions using Saccharomyces cerevisiae as a host organism. MYTH takes advantage of the observation that ubiquitin can be separated into two stable moieties: the C-terminal half of yeast ubiquitin (Cub) and the N-terminal half of the ubiquitin moiety (Nub). In MYTH, this principle is adapted for use as a 'sensor' of protein-protein interactions. Briefly, the integral membrane bait protein is fused to Cub which is linked to an artificial transcription factor. Prey proteins, either in individual or library format, are fused to the Nub moiety. Protein interaction between the bait and prey leads to reconstitution of the ubiquitin moieties, forming a full-length 'pseudo-ubiquitin' molecule. This molecule is in turn recognized by cytosolic deubiquitinating enzymes, resulting in cleavage of the transcription factor, and subsequent induction of reporter gene expression. The system is highly adaptable, and is particularly well-suited to high-throughput screening. It has been successfully employed to investigate interactions using integral membrane proteins from both yeast and other organisms.

Split-Ubiquitin Based Membrane Yeast Two-Hybrid MYTH System: A Powerful Tool For Identifying Protein-Protein Interactions

MYTH allows the sensitive detection of transient and stable interactions between proteins that are expressed in the model organism Saccharomyces cerevisiae. It has been successfully applied to study exogenous and yeast integral membrane proteins in order to identify their interacting partners in a high throughput manner.

基于分体式泛素膜酵母双杂交（神话）系统：一个强大的工具用于识别蛋白质 - 蛋白质相互作用

The fundamental biological and clinical importance of integral membrane proteins prompted the development of a yeast-based system for the high-throughput ...

Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations.
This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible1.

The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.

液相恢复GELFREE 8100分馏系统使用基于分子量分馏

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based ...

Deficient Pms2, ERCC1, Ku86, CcOI in Field Defects During Progression to Colon Cancer

In carcinogenesis, the "field defect" is recognized clinically because of the high propensity of survivors of certain cancers to develop other malignancies of the same tissue type, often in a nearby location. Such field defects have been indicated in colon cancer. The molecular abnormalities that are responsible for a field defect in the colon should be detectable at high frequency in the histologically normal tissue surrounding a colonic adenocarcinoma or surrounding an adenoma with advanced neoplasia (well on the way to a colon cancer), but at low frequency in the colonic mucosa from patients without colonic neoplasia.
Using immunohistochemistry, entire crypts within 10 cm on each side of colonic adenocarcinomas or advanced colonic neoplasias were found to be frequently reduced or absent in expression for two DNA repair proteins, Pms2 and/or ERCC1. Pms2 is a dual role protein, active in DNA mismatch repair as well as needed in apoptosis of cells with excess DNA damage. ERCC1 is active in DNA nucleotide excision repair. The reduced or absent expression of both ERCC1 and Pms2 would create cells with both increased ability to survive (apoptosis resistance) and increased level of mutability. The reduced or absent expression of both ERCC1 and Pms2 is likely an early step in progression to colon cancer.
DNA repair gene Ku86 (active in DNA non-homologous end joining) and Cytochrome c Oxidase Subunit I (involved in apoptosis) had each been reported to be decreased in expression in mucosal areas close to colon cancers. However, immunohistochemical evaluation of their levels of expression showed only low to modest frequencies of crypts to be deficient in their expression in a field defect surrounding colon cancer or surrounding advanced colonic neoplasia.
We show, here, our method of evaluation of crypts for expression of ERCC1, Pms2, Ku86 and CcOI. We show that frequency of entire crypts deficient for Pms2 and ERCC1 is often as great as 70% to 95% in 20 cm long areas surrounding a colonic neoplasia, while frequency of crypts deficient in Ku86 has a median value of 2% and frequency of crypts deficient in CcOI has a median value of 16% in these areas. The entire colon is 150 cm long (about 5 feet) and has about 10 million crypts in its mucosal layer. The defect in Pms2 and ERCC1 surrounding a colon cancer thus may include 1 million crypts. It is from a defective crypt that colon cancer arises.

Reduced/absent expression of Pms2 and/or ERCC1 in entire crypts is a frequent event within 10 cm on each side of colonic adenocarcinomas, likely the basis of a field defect with high mutability and progression to cancer. Deficiency in Ku86 or CcOI is much less frequent in these field defects.

缺乏PMS2，ERCC1，Ku86，视野缺损CcOI在结肠癌进展

In carcinogenesis, the "field defect" is recognized clinically because of the high propensity of survivors of certain cancers to develop other ...

Single-Molecule Imaging of Nuclear Transport

The utility of single molecule fluorescence microscopy approaches has been proven to be of a great avail in understanding biological reactions over the last decade. The investigation of molecular interactions with high temporal and spatial resolutions deep within cells has remained challenging due to the inherently weak signals arising from individual molecules. Recent works by Yang et al. demonstrated that narrow-field epifluorescence microscopy allows visualization of nucleocytoplasmic transport at the single molecule level. By the single molecule approach, important kinetics, such as nuclear transport time and efficiency, for signal-dependent and independent cargo molecules have been obtained. Here we described a protocol for the methodological approach with an improved spatiotemporal resolution of 0.4 ms and 12 nm. The improved resolution enabled us to capture transient active transport and passive diffusion events through the nuclear pore complexes (NPC) in semi-intact cells. We expect this method to be used in elucidating other binding and trafficking events within cells.

Single molecule microscopy approch provided novel insights into nuclear transport.

单分子成像核运输

The utility of single molecule fluorescence microscopy approaches has been proven to be of a great avail in understanding biological reactions over the ...

Bacterial Delivery of RNAi Effectors: Transkingdom RNAi

RNA interference (RNAi) represents a high effective mechanism for specific inhibition of mRNA expression. Besides its potential as a powerful laboratory tool, the RNAi pathway appears to be promising for therapeutic utilization. For development of RNA interference (RNAi)-based therapies, delivery of RNAi-mediating agents to target cells is one of the major obstacles. A novel strategy to overcome this hurdle is transkingdom RNAi (tkRNAi). This technology uses non-pathogenic bacteria, e.g. Escherichia coli, to produce and deliver therapeutic short hairpin RNA (shRNA) into target cells to induce RNAi. A first-generation tkRNAi-mediating vector, TRIP, contains the bacteriophage T7 promoter for expression regulation of a therapeutic shRNA of interest. Furthermore, TRIP has the Inv locus from Yersinia pseudotuberculosis that encodes invasin, which permits natural noninvasive bacteria to enter &beta;1-integrin-positive mammalian cells and the HlyA gene from Listeria monocytogenes, which produces listeriolysin O. This enzyme allows the therapeutic shRNA to escape from entry vesicles within the cytoplasm of the target cell. TRIP constructs are introduced into a competent non-pathogenic Escherichia coli strain, which encodes T7 RNA polymerase necessary for the T7 promoter-driven synthesis of shRNAs. A well-characterized cancer-associated target molecule for different RNAi strategies is ABCB1 (MDR1/P-glycoprotein, MDR1/P-gp). This ABC-transporter acts as a drug extrusion pump and mediates the "classical" ABCB1-mediated multidrug resistance (MDR) phenotype of human cancer cells which is characterized by a specific cross resistance pattern. Different ABCB1-expressing MDR cancer cells were treated with anti-ABCB1 shRNA expression vector bearing E. coli. This procedure resulted in activation of the RNAi pathways within the cancer cells and a considerable down regulation of the ABCB1 encoding mRNA as well as the corresponding drug extrusion pump. Accordingly, drug accumulation was enhanced in the pristine drug-resistant cancer cells and the MDR phenotype was reversed. By means of this model the data provide the proof-of-concept that tkRNAi is suitable for modulation of cancer-associated factors, e.g. ABCB1, in human cancer cells.

For development of RNA interference (RNAi)-based therapies, a novel strategy was developed, transkingdom RNAi (tkRNAi). This technology uses non-pathogenic bacteria to produce and deliver therapeutic short hairpin RNA (shRNA) into target cells. Here, tkRNAi was successfully applied for reversal of classical ABCB1-mediated multidrug resistance (MDR) of cancer cells.

细菌提供的RNAi效应：Transkingdom RNA干扰

RNA interference (RNAi) represents a high effective mechanism for specific inhibition of mRNA expression. Besides its potential as a powerful laboratory ...

Monitoring of Ubiquitin-proteasome Activity in Living Cells Using a Degron (dgn)-destabilized Green Fluorescent Protein (GFP)-based Reporter Protein

Proteasome is the main intracellular organelle involved in the proteolytic degradation of abnormal, misfolded, damaged or oxidized proteins 1, 2. Maintenance of proteasome activity was implicated in many key cellular processes, like cell's stress response 3, cell cycle regulation and cellular differentiation 4 or in immune system response 5. The dysfunction of the ubiquitin-proteasome system has been related to the development of tumors and neurodegenerative diseases 4, 6. Additionally, a decrease in proteasome activity was found as a feature of cellular senescence and organismal aging 7, 8, 9, 10. Here, we present a method to measure ubiquitin-proteasome activity in living cells using a GFP-dgn fusion protein. To be able to monitor ubiquitin-proteasome activity in living primary cells, complementary DNA constructs coding for a green fluorescent protein (GFP)&#x2013;dgn fusion protein (GFP&#x2013;dgn, unstable) and a variant carrying a frameshift mutation (GFP&#x2013;dgnFS, stable 11) are inserted in lentiviral expression vectors. We prefer this technique over traditional transfection techniques because it guarantees a very high transfection efficiency independent of the cell type or the age of the donor. The difference between fluorescence displayed by the GFP&#x2013;dgnFS (stable) protein and the destabilized protein (GFP-dgn) in the absence or presence of proteasome inhibitor can be used to estimate ubiquitin-proteasome activity in each particular cell strain. These differences can be monitored by epifluorescence microscopy or can be measured by flow cytometry.

Monitoring of Ubiquitin-proteasome Activity in Living Cells Using a Degron dgn-destabilized Green Fluorescent Protein GFP-based Reporter Protein

A method to monitor ubiquitin-proteasome activity in living cells is described. A degron-destabilized GFP- (GFP-dgn) and a stable GFP-dgnFS fusion protein are generated and transduced into the cell using a lentiviral expression vector. This technique allows to generate a stable GFP-dgn/GFP-dgnFS expressing cell line in which ubiquitin-proteasome activity can be easily assessed using epifluorescence or flow cytometry.

（DGN）一Degron不稳定的绿色荧光蛋白（GFP）的报告蛋白在活细胞内泛素 - 蛋白酶体活性的监测

Proteasome is the main intracellular organelle involved in the proteolytic degradation of abnormal, misfolded, damaged or oxidized proteins 1, 2. ...

Visualizing Bacteria in Nematodes using Fluorescent Microscopy

Symbioses, the living together of two or more organisms, are widespread throughout all kingdoms of life. As two of the most ubiquitous organisms on earth, nematodes and bacteria form a wide array of symbiotic associations that range from beneficial to pathogenic 1-3. One such association is the mutually beneficial relationship between Xenorhabdus bacteria and Steinernema nematodes, which has emerged as a model system of symbiosis 4. Steinernema nematodes are entomopathogenic, using their bacterial symbiont to kill insects 5. For transmission between insect hosts, the bacteria colonize the intestine of the nematode's infective juvenile stage 6-8. Recently, several other nematode species have been shown to utilize bacteria to kill insects 9-13, and investigations have begun examining the interactions between the nematodes and bacteria in these systems 9.
We describe a method for visualization of a bacterial symbiont within or on a nematode host, taking advantage of the optical transparency of nematodes when viewed by microscopy. The bacteria are engineered to express a fluorescent protein, allowing their visualization by fluorescence microscopy. Many plasmids are available that carry genes encoding proteins that fluoresce at different wavelengths (i.e. green or red), and conjugation of plasmids from a donor Escherichia coli strain into a recipient bacterial symbiont is successful for a broad range of bacteria. The methods described were developed to investigate the association between Steinernema carpocapsae and Xenorhabdus nematophila 14. Similar methods have been used to investigate other nematode-bacterium associations 9,15-18and the approach therefore is generally applicable.
The method allows characterization of bacterial presence and localization within nematodes at different stages of development, providing insights into the nature of the association and the process of colonization 14,16,19. Microscopic analysis reveals both colonization frequency within a population and localization of bacteria to host tissues 14,16,19-21. This is an advantage over other methods of monitoring bacteria within nematode populations, such as sonication 22or grinding 23, which can provide average levels of colonization, but may not, for example, discriminate populations with a high frequency of low symbiont loads from populations with a low frequency of high symbiont loads. Discriminating the frequency and load of colonizing bacteria can be especially important when screening or characterizing bacterial mutants for colonization phenotypes 21,24. Indeed, fluorescence microscopy has been used in high throughput screening of bacterial mutants for defects in colonization 17,18, and is less laborious than other methods, including sonication 22,25-27and individual nematode dissection 28,29.

To study the mutualism between Xenorhabdus bacteria and Steinernema nematodes, methods were developed to monitor bacterial presence and location within nematodes. The experimental approach, which can be applied to other systems, entails engineering bacteria to express the green fluorescent protein and visualizing, using fluorescence microscopy bacteria within the transparent nematode.

使用荧光显微镜可视化中的细菌线虫

 
Symbioses, the living together of two or more organisms, are widespread throughout all kingdoms of life. As two of the most ubiquitous organisms on ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

siRNA的筛选识别泛素和泛素样系统压力表生物学途径在培养的哺乳动物细胞

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...

A New Clarification Method to Visualize Biliary Degeneration During Liver Metamorphosis in Sea Lamprey (Petromyzon marinus)

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian countries, with a reported frequency of 1 in 5,000 in Taiwan. Although much is known about the management of biliary atresia, its pathogenesis is still elusive. The sea lamprey (Petromyzon marinus) provides a unique opportunity to examine the mechanism and progression of biliary degeneration. Sea lamprey develop through three distinct life stages: larval, parasitic, and adult. During the transition from larvae to parasitic juvenile, sea lamprey undergo metamorphosis with dramatic reorganization and remodeling in external morphology and internal organs. In the liver, the entire biliary system is lost, including the gall bladder and the biliary tree. A newly-developed method called &#8220;CLARITY&#8221; was modified to clarify the entire liver and the junction with the intestine in metamorphic sea lamprey. The process of biliary degeneration was visualized and discerned during sea lamprey metamorphosis by using laser scanning confocal microscopy. This method provides a powerful tool to study biliary atresia in a unique animal model.

A New Clarification Method to Visualize Biliary Degeneration During Liver Metamorphosis in Sea Lamprey Petromyzon marinus

Sea lamprey lose the gall bladder and bile ducts during metamorphosis, a process similar to human biliary atresia. A new fixation and clarification method (CLARITY) was modified to visualize the entire biliary tree using laser scanning confocal microscopy. This method provides a powerful tool to study biliary degeneration.

一种新的澄清方法，以可视化胆道变性在肝癌变态海七鳃鳗（ Petromyzon马里努斯）

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian ...