DFG(Deutsche Forschungsgemeinschaft) 보조금 BE1911/8-1, LOEWE 프로젝트 GLUE 및 협업 연구 센터인 Transport and Communication across Membranes(SFB807)에 재정 지원에 감사드립니다.

<ol>
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저자는 공개 할 것이 없습니다.

CF 발현을 최적화하기 위한 설정 및 전략과 기능성 MP를 나노디스크에 공동 번역하여 삽입하는 방법이 설명되어 있습니다. 필요한 장비는 바이오리액터, 프렌치 프레스 장치 또는 이와 유사한 장치, UV/VIS 및 형광 판독기, 2구획 구성 설정에 적합한 CF 반응 용기 및 온도 제어 인큐베이터로 구성됩니다. 추가 표준 장비로는 대장균 세포 수확을 위한 원심분리기와 S30 용해물 준비를 위해 최소 30,...

막 단백질(MPs)은 수성 환경에서의 불용성으로 인해 단백질 생산 연구에서 도전적인 표적입니다. 기존의 MP 생산 플랫폼은 대장균, 효모 또는 진핵 세포와 같은 세포 기반 시스템으로 구성됩니다. 합성된 재조합 MP는 세포막으로부터 추출되거나 봉입체로부터 재접힌다1. 세제 가용화 후, MP는 체외 재구성 프로토콜을 확립하여 적절한 막 환경으로 옮겨질 수 있습니다. 소포 및 리포좀 외에도 MP는 나노 디스크2 또는 살리 프로3 입자 형태의 평면 막으로 재구성되어 최근에 일상적인 기술이되었습니다. 그러나 이러한 모든 전략은 불안정화, 올리고머의 해리, 심지어 단백질 구조및 활성의 손실을 초래할 수 있는 MP와의 세제 접촉을 의미합니다4. 따라서 최적의 세제 가용화 및 재구성 조건을 위한 스크리닝은 지루하고 시간이 많이 소요될 수 있습니다5.
무세포(CF) 시스템의 개방 특성으로 인해 발현 반응이 정의된 지질 조성으로 미리 형성된 멤브레인에 직접 공급될 수 있습니다. 이 지질 기반 발현 모드(L-CF)에서, 합성된 MP는 제공된 이중층(6,7)에 공동 병진적으로 삽입할 기회를 갖는다(도 1). 평면 지질 이중층 디스크(8)를 둘러싸는 막 스캐폴드 단백질(MSP)로 구성된 나노디스크는 이러한 전략9, 10에 특히 적합한 것으로 보인다. 나노디스크는 다양한 지질로 시험관 내에서 일상적으로 조립할 수 있고, 매우 안정적이며, 스톡은 최대 1mM까지 농축될 수 있다. 그러나 대장균에서의 MSP 발현 및 정제가 필요합니다. 대안적인 전략으로서, MSP는 리포좀11,12,13과 함께 공급된 CF 반응에서 표적 MP와 함께 발현될 수 있다. MSP와 MP 모두에 대한 DNA 템플릿이 반응에 추가되고 발현 시 MP/나노디스크가 형성될 수 있습니다. MSP 생산은 피할 수 있지만 공동 발현 전략은 최종 DNA 주형 농도를 신중하게 미세 조정해야 하며 샘플 생산 효율성의 더 높은 변동을 기대할 수 있습니다.
미리 형성된 나노 디스크의 막에 MP의 공동 번역 삽입은 트랜스 로콘 기계 및 신호 서열13,14,15,16과 독립적 인 비 생리 학적 및 여전히 크게 알려지지 않은 메커니즘입니다. 삽입 효율의 주요 결정 인자는 막 단백질의 유형뿐만 아니라 제공된 막의 지질 조성이며, 음전하를 띤 지질에 대한 빈번한 선호15,17. 나노디스크 막이 크기가 상대적으로 제한되어 있기 때문에, MP 삽입시 상당한 양의 지질이 방출된다(18). 나노디스크 크기의 변화는 더 높은 올리고머 MP 복합체(15,18)의 삽입 및 튜닝을 가능하게 한다. 그 중에서도 이온 채널 KcsA, 이온 펌프 프로테오르호돕신(PR) 및 다제 수송체 EmrE15,18에 대해 호모올리고머 복합체의 올바른 조립이 나타났습니다. MP는 상대적으로 동일한 주파수로 양쪽에서 대칭 나노 디스크 막으로 들어갈 가능성이 높습니다. 따라서 하나의 나노 디스크에 삽입 된 상이한 단량체 또는 올리고머는 반대 배향을 가질 수 있음을 고려해야한다. 그러나, 배향의 편향은 PR 헥사머 및 KcsA 사량체18의 형성에 대해 보고된 바와 같은 협력적 삽입 메커니즘에 의해 야기될 수 있다. MP 방향의 추가 편향은 아마도 나노 디스크 멤브레인의 가장자리에 삽입 된 MP의 방향 스위치로 인해 발생할 수 있습니다.
E. coli 균주로부터 CF 용해물의 생산은 신뢰할 수 있는 일상적인 기술이며 거의 모든 생화학 실험실(19,20)에서 수행될 수 있습니다. 이황화 다리 형성 외에도 MP가 대장균 용해물을 사용하여 합성되는 경우 대부분의 다른 번역 후 변형이 없다는 점을 고려해야합니다. 이것은 구조 연구를 위해 더 균질한 샘플을 생성할 수 있지만 개별 MP 표적의 기능에 대한 잠재적 영향을 배제해야 할 수도 있습니다. 그러나, E. coli CF 용해물에서 G- 단백질 결합 수용체 (GPCR) 14,21,22, 진핵 수송 체 23 또는 큰 이종 이성질체 어셈블리 24의 고품질 샘플의 효율적인 생산은 복잡한 표적에 대한 적합성을 나타냅니다. 시료의 분취 스케일 양(≈ 1 mg/mL)은 반응 혼합물(RM)과 공급 혼합물(FM) 구획으로 구성된 2구획 연속 교환 무세포(CECF) 구성으로 얻을 수 있습니다. FM 부피는 RM 부피의 15 내지 20배를 초과하고, 저분자량 에너지 화합물 및 전구체(19)의 저장소를 제공한다. 따라서 발현 반응은 수 시간 동안 연장되고 MP 표적의 최종 수율이 증가합니다. RM 및 FM 구획은 10-14kDa 컷오프가있는 투석막으로 분리됩니다. 두 구획에는 CECF 반응 용기의 특수 설계가 필요합니다(그림 1). RM 용기로서의 상업용 투석 카세트와 FM을 보유하는 맞춤형 플렉시 유리 용기가 적합한 예입니다. MP 수율은 RM:FM 비율을 수정하거나 일정 기간 배양 후 FM을 교환하여 추가로 조작할 수 있습니다.
MP의 수율과 품질은 종종 반응 파라미터의 집중적인 최적화를 필요로 합니다. CF 발현의 중요한 장점은 MP의 개별 요구 사항에 따라 거의 모든 화합물을 수정하고 미세 조정할 수 있다는 것입니다. 간단한 전략은 먼저 기본 생산 프로토콜을 수립하여 MP의 수율을 개선하는 데 집중한 다음 반응 및 접힘 조건을 미세 조정하여 MP 품질을 최적화하는 것입니다. CF 용해물에 생리학적 과정이 없고 복잡성이 감소하면MP25의 효율적인 생산을 위한 높은 성공률이 발생합니다. DNA 주형 설계 및Mg2+ 이온 농도의 최적화를 위한 통상적인 고려사항은 대부분의 경우 만족스러운 수율(26)을 얻기에 충분하다. 발현 모드에 따라, MP 품질의 최적화는 더 다양한 파라미터가 스크리닝될 필요가 있기 때문에(14,17,22) 시간이 많이 소요될 수 있다.
설명된 CF 발현 플랫폼을 확립하려면 대장균 CF 용해물(i), T7 RNA 중합효소(ii), 나노디스크(iii) 및 염기성 CECF 반응 화합물(iv)의 생산에 프로토콜이 필요합니다(그림 1). E. coli K12 균주 A1927 또는 BL21 유도체는 효율적인 S30(30,000 x g에서 원심분리) 용해물의 제조에 자주 사용됩니다. S30 용해물 외에, 다른 g-force(예: S12)에서 원심분리된 상응하는 용해물이 사용될 수 있다. 용해물은 발현 효율과 프로테옴 복잡성이 다릅니다. 기재된 프로토콜에 의해 제조된 S30 용해물의 프로테옴은도 28에서 상세히 연구되었다. S30 프로테옴에는 여전히 이온 채널의 발현 및 분석시 배경 문제를 일으킬 수있는 일부 잔류 외막 단백질이 포함되어 있습니다. 이러한 표적의 경우 S80-S100 용해물을 사용하는 것이 좋습니다. 용해물 준비 중 유용한 변형은 세포의 중간 로그 성장 단계에서 열 충격과 에탄올 공급을 결합하여 SOS 반응을 유도하는 것입니다. 생성된 HS30 용해물은 샤페론이 풍부하고, 개선된 MP 폴딩(22)을 위해 S30 용해물과의 블렌드에 사용될 수 있다. 대장균 용해물에서의 CF 발현은 T7 RNA 중합효소(T7RNAP)에 의해 제어되는 프로모터를 포함하는 DNA 주형과의 결합된 전사/번역 과정으로 작동됩니다. 효소는 pAR1219 플라스미드29를 운반하는 BL21(DE3) 스타 세포에서 효율적으로 생산될 수 있습니다.
MSP1E3D1의 두 사본은 직경이 10-12 nm 인 하나의 나노 디스크로 조립되지만 아래에 설명 된 프로토콜은 다른 MSP 유도체에도 작동 할 수 있습니다. 그러나, MSP1E3D1로 형성된 것보다 큰 나노디스크는 덜 안정한 경향이 있는 반면, MSP1과 같은 MSP 유도체로 형성된 더 작은 나노디스크는 더 큰 MPs 또는 MP 복합체를 수용하지 못할 수 있다. MSP1E3D1 나노디스크는 매우 다양한 지질 또는 지질 혼합물로 시험관내에서 조립할 수 있습니다. 예비 성형 된 나노 디스크는 일반적으로 -80 ° C에서 > 1 년 동안 안정하지만 안정성은 지질 성분에 따라 다를 수 있습니다. MP의 접힘 및 안정성에 대한 지질 효과를 스크리닝하려면 대표적인 다양한 지질/지질 혼합물로 조립된 포괄적인 나노디스크 세트를 준비해야 합니다. 다음의 지질은 좋은 출발 선택을 제공할 수 있다: 1,2-디미리스토일-sn-글리세로-3-포스포-(1'-락-글리세롤) (DMPG), 1,2-디미리스토일-sn-글리세로-3-포스포콜린 (DMPC), 1,2-디올레오일-sn-글리세로-3-포스포-락-(1-글리세롤) (DOPG), 1,2-디올레오일-sn-글리세로-3-포스포콜린 (DOPC), 1-팔미토일-2-올레오일-sn-글리세로-3-포스포-(1'-rac-glycerol) (POPG) 및 1-팔미토일-2-올레오일-글리세로-3-포스포콜린 (POPC).
3mL CECF 반응의 제조를 위한 프로토콜이 기재되어 있다. 1:1 비율로 추가 확장 또는 축소가 가능합니다. 2구획 CECF 구성의 경우 모든 화합물을 포함하는 RM과 저분자량 화합물만 포함하는 FM을 준비해야 합니다. 10-14kDa MWCO의 상업용 3mL 투석 장치를 RM 용기로 사용할 수 있으며, 이를 FM을 고정하는 맞춤형 플렉시 유리 용기에 넣을 수 있습니다(그림 1D)30. RM:FM의 비율은 1:20이므로 3mL RM에 대해 60mL의 FM을 준비해야 합니다. 여러 성분의 품질, 농도 또는 유형은 합성된 MP의 최종 수율 및/또는 품질에 중요할 수 있습니다(표 1). DNA 주형은 공개된 가이드라인에 따라 제조되어야 하며, 표적의 판독 프레임의 코돈 최적화는 생성물 수율을 더욱 크게 향상시킬 수 있다(26). 분취 규모 CECF 반응의 경우, PR 생산을 위한 확립된 프로토콜이 기재되어 있다. 새로운 MP에 대한 발현 프로토콜을 확립하려면 일반적으로 수율과 품질을 개선하기 위해 특정 화합물(표 1)의 최적화 스크린을 수행해야 합니다. Mg2+ 이온의 경우, 상이한 DNA 주형에 대해 유의한 변화를 자주 보여주는 잘 집중된 최적 농도가 존재한다. T7RNAP 또는 S30 용해물의 새로운 배치와 같은 다른 CF 반응 화합물은 최적의Mg2+ 농도를 추가로 이동시킬 수 있습니다. 예로서, 14-24 mM 농도의 범위 내에서 및 2 mM의 단계에서의 전형적인Mg2+ 화가 설명된다. 각 농도는 중복 및 분석 규모 CECF 반응으로 스크리닝됩니다. CECF 반응 용기로서, RM을 보유하는 맞춤형 Mini-CECF 플렉시글라스 용기(30 )가 FM을 보유하는 표준 24웰 마이크로플레이트와 조합하여 사용된다(도 1B). 대안적으로, 96-딥 웰 마이크로플레이트 또는 적절한 셋업의 다른 상용 투석기 장치와 조합된 상업용 투석 카트리지가 사용될 수 있다(도 1C).

<table>
	<tbody>
		<tr>
			<td>1,2-dimyristoyl-sn-glycero-3-phospho-(1&#39;-rac-glycerol) (sodium salt) (DMPG)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>840445P</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>850345C</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-dioleoyl-sn-glycero-3-phosphocholine (sodium salt) (DOPC)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>850375C</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2 dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (sodium salt) (DOPG)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>840475C</td>
			<td></td>
		</tr>
		<tr>
			<td>1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>850457C</td>
			<td></td>
		</tr>
		<tr>
			<td>1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1&#39;-rac-glycerol) (sodium salt) (POPG)</td>
			<td>Avanti Polar Lipids (USA)</td>
			<td>840034C</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Amino-2-(hydroxymethyl)-propan-1,3-diol (Tris)</td>
			<td>Carl Roth (Germany)</td>
			<td>4855</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>Carl Roth (Germany)</td>
			<td>4227</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Propanol</td>
			<td>Carl Roth (Germany)</td>
			<td>9781</td>
			<td></td>
		</tr>
		<tr>
			<td>[3H]-dihydroalprenolol Hydrochloride</td>
			<td>American Radiolabeled Chemicals (USA)</td>
			<td>ART0134</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetyl phosphate lithium potassium salt (ACP)</td>
			<td>Merck (Germany)</td>
			<td>1409</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#8217;-triphosphate (ATP)</td>
			<td>Sigma Aldrich (Germany)</td>
			<td>A9251</td>
			<td></td>
		</tr>
		<tr>
			<td>Alprenolol hydrochloride</td>
			<td>Merck (Germany)</td>
			<td>A0360000</td>
			<td></td>
		</tr>
		<tr>
			<td>Anion exchange chromatography column material: Q-sepharose&#174;</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>Q1126</td>
			<td></td>
		</tr>
		<tr>
			<td>Autoclave Type GE 446EC-1</td>
			<td>Gettinge (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bioreactor Type 884 124/1</td>
			<td>B.Braun (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Sorvall RC12BP+; Thermo Scientific (Germany); Sorvall RC-5C; Thermo Scientific (Germany); Mikro 22 R; Hettich (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cholic acid</td>
			<td>Carl Roth (Germany)</td>
			<td>8137</td>
			<td></td>
		</tr>
		<tr>
			<td>Coomassie Brilliant Blue R250</td>
			<td>Carl Roth (Germany)</td>
			<td>3862</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture flasks 500 ml baffled flasks, 2 l baffled flasks</td>
			<td>Schott Duran (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cytidine 5&#39;-triphosphate disodium salt</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>C1506</td>
			<td></td>
		</tr>
		<tr>
			<td>D-glucose monohydrate</td>
			<td>Carl Roth (Germany)</td>
			<td>6780</td>
			<td></td>
		</tr>
		<tr>
			<td>Di-potassiumhydrogen phosphate trihydrate</td>
			<td>Carl Roth (Germany)</td>
			<td>6878</td>
			<td></td>
		</tr>
		<tr>
			<td>Dialysis tubing SpectrumTM Labs Spectra/PorTM 12-14 kD MWCO Standard RC tubing</td>
			<td>Fisher Scientific (Germany)</td>
			<td>8700152</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreit</td>
			<td>Carl Roth (Germany)</td>
			<td>6908</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Carl Roth (Germany)</td>
			<td>K928</td>
			<td></td>
		</tr>
		<tr>
			<td>Folinic acid calcium salt hydrate</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>47612</td>
			<td></td>
		</tr>
		<tr>
			<td>French pressure cell disruptor</td>
			<td>SLM; Amico Instruments (USA)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Carl Roth (Germany)</td>
			<td>3783</td>
			<td></td>
		</tr>
		<tr>
			<td>Guanosine 5&#39;-triphosphate di-sodium salt (GTP)</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>G8877</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric Acid</td>
			<td>Carl Roth (Germany)</td>
			<td>K025</td>
			<td></td>
		</tr>
		<tr>
			<td>IMAC column: HiTrap IMAC HP 5 mL</td>
			<td>GE Life Sciences (Germany)</td>
			<td>GE17-5248</td>
			<td></td>
		</tr>
		<tr>
			<td>Imidazole</td>
			<td>Carl Roth (Germany)</td>
			<td>3899</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl-&#946;-D-thiogalactopyranosid (IPTG)</td>
			<td>Carl Roth (Germany)</td>
			<td>2316</td>
			<td></td>
		</tr>
		<tr>
			<td>Kanamycin</td>
			<td>Carl Roth (Germany)</td>
			<td>T832</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Alanine</td>
			<td>Carl Roth (Germany)</td>
			<td>3076.1</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Arginine</td>
			<td>Carl Roth (Germany)</td>
			<td>6908</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Asparagine</td>
			<td>Carl Roth (Germany)</td>
			<td>HN23</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Aspartic Acid</td>
			<td>Carl Roth (Germany)</td>
			<td>T202</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Cysteine</td>
			<td>Carl Roth (Germany)</td>
			<td>T203</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamic Acid</td>
			<td>Carl Roth (Germany)</td>
			<td>3774</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td>Carl Roth (Germany)</td>
			<td>3772</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glycine</td>
			<td>Carl Roth (Germany)</td>
			<td>3187</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Histidine</td>
			<td>Carl Roth (Germany)</td>
			<td>3852</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Isoleucine</td>
			<td>Carl Roth (Germany)</td>
			<td>3922</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Leucine</td>
			<td>Carl Roth (Germany)</td>
			<td>1699</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Lysine</td>
			<td>Carl Roth (Germany)</td>
			<td>4207</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Methionine</td>
			<td>Carl Roth (Germany)</td>
			<td>9359</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Proline</td>
			<td>Carl Roth (Germany)</td>
			<td>1713</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Phenylalanine</td>
			<td>Carl Roth (Germany)</td>
			<td>1709</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Serine</td>
			<td>Carl Roth (Germany)</td>
			<td>4682</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Threonine</td>
			<td>Carl Roth (Germany)</td>
			<td>1738</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Tryptophane</td>
			<td>Carl Roth (Germany)</td>
			<td>7700</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Tyrosine</td>
			<td>Carl Roth (Germany)</td>
			<td>T207</td>
			<td></td>
		</tr>
		<tr>
			<td>MD100 dialysis units</td>
			<td>Scienova (Germany)</td>
			<td>40077</td>
			<td></td>
		</tr>
		<tr>
			<td>N-2-Hydroxyethylpiperazine-N&#39;-2-ethansulfonic acid (HEPES)</td>
			<td>Carl Roth (Germany)</td>
			<td>6763</td>
			<td></td>
		</tr>
		<tr>
			<td>n-dodecylphosphocholine</td>
			<td>Antrace (USA)</td>
			<td>F308S</td>
			<td></td>
		</tr>
		<tr>
			<td>PAGE chamber: Mini-Protean Tetra Cell</td>
			<td>Biorad (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PAGE gel casting system: Mini Protean Handcast systems</td>
			<td>Biorad (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PAGE gel power supply: Power Pac 3000</td>
			<td>Biorad (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tryptone/peptone from caseine</td>
			<td>Carl Roth (Germany)</td>
			<td>6681</td>
			<td></td>
		</tr>
		<tr>
			<td>Peristaltic pump: ip-12</td>
			<td>Ismatec (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphoenol pyruvate monopotassium salt</td>
			<td>Sigma Aldrich (Germany)</td>
			<td>860077</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium dihydrogen phosphate</td>
			<td>Carl Roth (Germany)</td>
			<td>P018</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium acetate</td>
			<td>Carl Roth (Germany)</td>
			<td>4986</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Carl Roth (Germany)</td>
			<td>6781</td>
			<td></td>
		</tr>
		<tr>
			<td>Pyruvate Kinase</td>
			<td>Roche (Germany)</td>
			<td>10109045001</td>
			<td></td>
		</tr>
		<tr>
			<td>Scintillation counter: Hidex 300 SL</td>
			<td>Hidex (Finland)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SDS pellets</td>
			<td>Carl Roth (Germany)</td>
			<td>8029</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>K305</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Carl Roth (Germany)</td>
			<td>P029</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrophotometer Nanodrop</td>
			<td>Peqlab (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrophotometer/fluorescence reader Spark&#174;</td>
			<td>Tecan (Switzerland)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>tRNA (E. coli)</td>
			<td>Roche (Germany)</td>
			<td>10109550001</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra sonificator</td>
			<td>Labsonic U, B. Braun (Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Uridine 5&#8217;-triphosphate tri-sodium salt (UTP)</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>U6625</td>
			<td></td>
		</tr>
		<tr>
			<td>Y-30 antifoam</td>
			<td>Sigma-Aldrich (Germany)</td>
			<td>A6457</td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast extract</td>
			<td>Carl Roth (Germany)</td>
			<td>2904</td>
			<td></td>
		</tr>
	</tbody>
</table>

co-translational insertion of membrane proteins into preformed nanodiscs

무세포 발현 시스템을 사용하면 반응 환경을 맞춤 설계하여 막 단백질과 같은 복잡한 단백질의 기능적 접힘도 지원할 수 있습니다. 막 단백질을 나노 디스크로 공급되는 미리 형성되고 정의된 막으로 공동 번역 삽입 및 접는 실험 절차가 시연됩니다. 이 프로토콜은 세제가 전혀 없으며 하루 이내에 밀리그램의 정제된 샘플을 생성할 수 있습니다. 생성된 멤브레인 단백질/나노디스크 샘플은 결정화, 핵자기 공명 또는 전자 현미경과 같은 다양한 기능 연구 및 구조 응용 분야에 사용할 수 있습니다. 무세포 용해물, 설계된 멤브레인이 있는 나노디스크, 중요 스톡 용액 및 2구획 무세포 발현 반응의 조립과 같은 기본 핵심 구성 요소의 준비에 대해 설명합니다. 막 단백질의 접힘 요구 사항은 매우 다양할 수 있으므로 이 프로토콜의 주요 초점은 중요한 염기성 반응 화합물, 나노디스크의 막 조성, 산화 환원 및 샤페론 환경 또는 DNA 주형 설계와 같은 샘플 품질에 중요한 파라미터 및 반응 단계의 조절입니다. 전체 과정은 프로테오르호돕신과 G-단백질 결합 수용체의 합성으로 입증됩니다.

미세 조정 반응 화합물이 합성된 MP의 최종 수율 또는 품질에 미치는 영향이 예시됩니다. 빈번한 일상적인 접근법은 시스템 효율의 편리한 모니터로서 녹색 형광 단백질 (GFP)의 발현에 의해 CF 반응에서 최적의 Mg2+ 농도를 조정하는 것입니다. 예를 들어, GFP는 14와 24 mM 사이의 Mg 2+ 농도에서pET-21a(+) 벡터로부터 합성되었습니다(그림 2). SDS-PAGE 분석은 20 mM에서 최...

Watch this Scientific Journal Video about Co-Translational Insertion of Membrane Proteins into Preformed Nanodiscs at JoVE.com

Co-Translational Insertion of Membrane Proteins into Preformed Nanodiscs

사전 형성된 나노디스크에 공동 번역하여 삽입하면 세제와의 접촉 없이 정의된 지질 환경에서 무세포 합성된 막 단백질을 연구할 수 있습니다. 이 프로토콜은 필수 시스템 구성 요소의 준비와 발현 효율성 및 샘플 품질을 개선하기 위한 중요한 파라미터를 설명합니다.

막 단백질을 미리 형성된 나노디스크에 공동 번역 삽입

Cell-free expression systems allow the tailored design of reaction environments to support the functional folding of even complex proteins such as ...

co-translational-insertion-membrane-proteins-into-preformed

Research

JoVE Journal

Biochemistry

3.2K 조회수.  Goethe University Frankfurt. 사전 형성된 나노디스크에 공동 번역하여 삽입하면 세제와의 접촉 없이 정의된 지질 환경에서 무세포 합성된 막 단백질을 연구할 수 있습니다. 이 프로토콜은 필수 시스템 구성 요소의 준비와 발현 효율성 및 샘플 품질을 개선하기 위한 중요한 파라미터를 설명합니다.

비디오: Co-Translational Insertion of Membrane Proteins into Preformed Nanodiscs

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating these studies, reincorporation of detergent-solubilized membrane proteins into liposomes is a stochastic process where protein topology is impossible to enforce. This paper offers an alternative method to these challenging techniques that utilizes a liposome-based scaffold. Protein solubility is enhanced by deletion of the transmembrane domain, and these amino acids are replaced with a tethering moiety, such as a His-tag. This tether interacts with an anchoring group (Ni2+ coordinated by nitrilotriacetic acid (NTA(Ni2+)) for His-tagged proteins), which enforces a uniform protein topology at the surface of the liposome. An example is presented wherein the interaction between Dynamin-related protein 1 (Drp1) with an integral membrane protein, Mitochondrial Fission Factor (Mff), was investigated using this scaffold liposome method. In this work, we have demonstrated the ability of Mff to efficiently recruit soluble Drp1 to the surface of liposomes, which stimulated its GTPase activity. Moreover, Drp1 was able to tubulate the Mff-decorated lipid template in the presence of specific lipids. This example demonstrates the effectiveness of scaffold liposomes using structural and functional assays and highlights the role of Mff in regulating Drp1 activity.

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

This paper describes a method for assessing the interactions and assemblies of integral membrane proteins in vitro with various partner factors in a lipid-proximal environment.

비계 리포좀을 사용하여 근위 지질 단백질 - 단백질 상호 작용을 재구성<em&gt; 체외</em

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating ...

연구

생화학

Method to Visualize and Analyze Membrane Interacting Proteins by Transmission Electron Microscopy

Monotopic proteins exert their function when attached to a membrane surface, and such interactions depend on the specific lipid composition and on the availability of enough area to perform the function. Nanodiscs are used to provide a membrane surface of controlled size and lipid content. In the absence of bound extrinsic proteins, sodium phosphotungstate-stained nanodiscs appear as stacks of coins when viewed from the side by transmission electron microscopy (TEM). This protocol is therefore designed to intentionally promote stacking; consequently, the prevention of stacking can be interpreted as the binding of the membrane-binding protein to the nanodisc. In a further step, the TEM images of the protein-nanodisc complexes can be processed with standard single-particle methods to yield low-resolution structures as a basis for higher resolution cryoEM work. Furthermore, the nanodiscs provide samples suitable for either TEM or non-denaturing gel electrophoresis. To illustrate the method, Ca2+-induced binding of 5-lipoxygenase on nanodiscs is presented.

Many proteins perform their function when attached to membrane surfaces. The binding of extrinsic proteins on nanodisc membranes can be indirectly imaged by transmission electron microscopy. We show that the characteristic stacking (rouleau) of nanodiscs induced by the negative stain sodium phosphotungstate is prevented by the binding of extrinsic protein.

방법은 시각화 및 투과 전자 현미경에 의해 막 상호 작용하는 단백질을 분석하는

Monotopic proteins exert their function when attached to a membrane surface, and such interactions depend on the specific lipid composition and on the ...

Nitrogen Cavitation and Differential Centrifugation Allows for Monitoring the Distribution of Peripheral Membrane Proteins in Cultured Cells

Cultured cells are useful for studying the subcellular distribution of proteins, including peripheral membrane proteins. Genetically encoded fluorescently tagged proteins have revolutionized the study of subcellular protein distribution. However, it is difficult to quantify the distribution with fluorescent microscopy, especially when proteins are partially cytosolic. Moreover, it is often important to study endogenous proteins. Biochemical assays such as immunoblots remain the gold standard for quantification of protein distribution after subcellular fractionation. Although there are commercial kits that aim to isolate cytosolic or certain membrane fractions, most of these kits are based on extraction with detergents, which may be unsuitable for studying peripheral membrane proteins that are easily extracted from membranes. Here we present a detergent-free protocol for cellular homogenization by nitrogen cavitation and subsequent separation of cytosolic and membrane-bound proteins by ultracentrifugation. We confirm the separation of subcellular organelles in soluble and pellet fractions across different cell types, and compare protein extraction among several common non-detergent-based mechanical homogenization methods. Among several advantages of nitrogen cavitation is the superior efficiency of cellular disruption with minimal physical and chemical damage to delicate organelles. Combined with ultracentrifugation, nitrogen cavitation is an excellent method to examine the shift of peripheral membrane proteins between cytosolic and membrane fractions.

Here we present protocols for detergent-free homogenization of cultured mammalian cells based on nitrogen cavitation and subsequent separation of cytosolic and membrane-bound proteins by ultracentrifugation. This method is ideal for monitoring the partitioning of peripheral membrane proteins between soluble and membrane fractions.

질소 현상과 차등 원심 분리 배양된 세포의 주변 막 단백질의 분포를 모니터링 가능

Cultured cells are useful for studying the subcellular distribution of proteins, including peripheral membrane proteins. Genetically encoded fluorescently ...

Detergent-free Ultrafast Reconstitution of Membrane Proteins into Lipid Bilayers Using Fusogenic Complementary-charged Proteoliposomes.

Detergents are indispensable for delivery of membrane proteins into 30-100 nm small unilamellar vesicles, while more complex, larger model lipid bilayers are less compatible with detergents.
Here we describe a strategy for bypassing this fundamental limitation using fusogenic oppositely charged liposomes bearing a membrane protein of interest. Fusion between such vesicles occurs within 5 min in a low ionic strength buffer. Positively charged fusogenic liposomes can be used as simple shuttle vectors for detergent-free delivery of membrane proteins into biomimetic target lipid bilayers, which are negatively charged. We also show how to reconstitute membrane proteins into fusogenic proteoliposomes with a fast 30-min protocol.
Combining these two approaches, we demonstrate a fast assembly of an electron transport chain consisting of two membrane proteins from E. coli, a primary proton pump bo3-oxidase and F1Fo ATP synthase, in membranes of vesicles of various sizes, ranging from 0.1 to &#62;10 microns, as well as ATP production by this chain.

Here we present two ultrafast protocols for reconstitution of membrane proteins into fusogenic proteoliposomes, and fusion of such proteoliposomes with target lipid bilayers for detergent-free delivery of these membrane proteins into the postfusion bilayer. The combination of these approaches enables fast and easily controlled assembly of complex multi-component membrane systems.

세제 없는 보완 청구 Proteoliposomes Fusogenic를 사용 하 여 지질 Bilayers에 막 단백질의 초고속 재구성.

Detergents are indispensable for delivery of membrane proteins into 30-100 nm small unilamellar vesicles, while more complex, larger model lipid bilayers ...

Detection of Detergent-sensitive Interactions Between Membrane Proteins

Our ability to explore protein-protein interactions is the key to understanding regulatory connections in the cell. However, detection of protein-protein interactions in many cases is associated with significant experimental challenges. In particular, sorting receptors interact with their protein cargo in the lumen of the membrane compartments often in a detergent-sensitive fashion, making co-immunoprecipitation of these proteins unusable. Binding of the sorting receptor sortilin to glucose transporter GLUT4 may serve as an example of weak luminal interactions between membrane proteins. Here, we describe a fast, simple, and inexpensive assay to validate the interaction between sortilin and GLUT4. For that, we have designed and chemically synthesized the myc-tagged peptide corresponding to the potential sortilin-binding epitope in the luminal part of GLUT4. Sortilin tagged with six histidines was expressed in mammalian cells, and isolated from cell lysates using Cobalt beads. Sortilin immobilized on the beads was incubated with the peptide solution at different pH values, and the eluted material was analyzed by Western blotting. This assay can be easily adapted to study other detergent-sensitive protein-protein interactions.

We describe a protocol for detection of detergent-sensitive interactions between membrane proteins using binding of the sorting receptor, sortilin, to the first luminal loop of the glucose transporter protein, GLUT4, as an example.

세제에 민감한 막 단백질 사이 상호 작용의 탐지

Our ability to explore protein-protein interactions is the key to understanding regulatory connections in the cell. However, detection of protein-protein ...

A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts

A variety of biological processes involves cell-cell interactions, typically mediated by proteins that interact at the interface between neighboring cells. Of interest, only few assays are capable of specifically probing such interactions directly in living cells. Here, we present an assay to measure the binding of proteins expressed at the surfaces of neighboring cells, at cell-cell contacts. This assay consists of two steps: mixing of cells expressing the proteins of interest fused to different fluorescent proteins, followed by fluorescence fluctuation spectroscopy measurements at cell-cell contacts using a confocal laser scanning microscope. We demonstrate the feasibility of this assay in a biologically relevant context by measuring the interactions of the amyloid precursor-like protein 1 (APLP1) across cell-cell junctions. We provide detailed protocols on the data acquisition using fluorescence-based techniques (scanning fluorescence cross-correlation spectroscopy, cross-correlation number and brightness analysis) and the required instrument calibrations. Further, we discuss critical steps in the data analysis and how to identify and correct external, spurious signal variations, such as those due to photobleaching or cell movement.
In general, the presented assay is applicable to any homo- or heterotypic protein-protein interaction at cell-cell contacts, between cells of the same or different types and can be implemented on a commercial confocal laser scanning microscope. An important requirement is the stability of the system, which needs to be sufficient to probe diffusive dynamics of the proteins of interest over several minutes.

This protocol describes a fluorescence fluctuation spectroscopy-based approach to investigate interactions among proteins mediating cell-cell interactions, i.e. proteins localized in cell junctions, directly in living cells. We provide detailed guidelines on instrument calibration, data acquisition and analysis, including corrections to possible artefact sources.

셀 연락처에서 단백질 단백질 상호 작용의 형광 변동 분광학 분석 결과

A variety of biological processes involves cell-cell interactions, typically mediated by proteins that interact at the interface between neighboring ...

PeptiQuick, a One-Step Incorporation of Membrane Proteins into Biotinylated Peptidiscs for Streamlined Protein Binding Assays

Membrane proteins, including transporters, channels, and receptors, constitute nearly one-fourth of the cellular proteome and over half of current drug targets. Yet, a major barrier to their characterization and exploitation in academic or industrial settings is that most biochemical, biophysical, and drug screening strategies require these proteins to be in a water-soluble state. Our laboratory recently developed the peptidisc, a membrane mimetic offering a &#8220;one-size-fits-all&#8221; approach to the problem of membrane protein solubility. We present here a streamlined protocol that combines protein purification and peptidisc reconstitution in a single chromatographic step. This workflow, termed PeptiQuick, allows for bypassing dialysis and incubation with polystyrene beads, thereby greatly reducing exposure to detergent, protein denaturation, and sample loss. When PeptiQuick is performed with biotinylated scaffolds, the preparation can be directly attached to streptavidin-coated surfaces. There is no need to biotinylate or modify the membrane protein target. PeptiQuick is showcased here with the membrane receptor FhuA and antimicrobial ligand colicin M, using biolayer interferometry to determine the precise kinetics of their interaction. It is concluded that PeptiQuick is a convenient way to prepare and analyze membrane protein-ligand interactions within one&#160;day in a detergent-free environment.

We present a method that combines membrane protein purification and reconstitution into peptidiscs in a single chromatographic step. Biotinylated scaffolds are used for direct surface attachment and measurement of protein-ligand interactions via biolayer interferometry.

PeptiQuick, 간소화 된 단백질 결합 검정을 위한 생체 면역 펩티디스크에 막 단백질의 한 단계 통합

Membrane proteins, including transporters, channels, and receptors, constitute nearly one-fourth of the cellular proteome and over half of current drug ...

Acyl-PEGyl Exchange Gel Shift Assay for Quantitative Determination of Palmitoylation of Brain Membrane Proteins

Activity-dependent alterations in the levels of synaptic AMPA receptors (AMPARs) within the postsynaptic density (PSD) is thought to represent a cellular mechanism for learning and memory. Palmitoylation regulates localization and function of many synaptic proteins including AMPA-Rs, auxiliary factors and synaptic scaffolds in an activity-dependent manner. We identified the synapse differentiation induced gene (SynDIG) family of four genes (SynDIG1-4) encoding brain-specific transmembrane proteins that associate with AMPARs and regulate synapse strength. SynDIG1 is palmitoylated at two cysteine residues located at positions 191 and 192 in the juxta-transmembrane region important for activity-dependent excitatory synapse development. Here, we describe an innovative biochemical approach, the acyl-PEGyl exchange gel shift (APEGS) assay, to investigate the palmitoylation state of any protein of interest and demonstrate its utility with the SynDIG family of proteins in mouse brain lysates.

Palmitoylation entails the incorporation of a 16-carbon palmitate moiety to cysteine residues of target proteins in a reversible manner. Here, we describe a biochemical approach, the acyl-PEGyl exchange gel shift (APEGS) assay, to investigate the palmitoylation state of any protein of interest in mouse brain lysates.

아실-PEGyl 교환 젤 시프트 분석은 뇌막 단백질의 팔미토일화의 정량적 측정을 위한 것입니다.

Activity-dependent alterations in the levels of synaptic AMPA receptors (AMPARs) within the postsynaptic density (PSD) is thought to represent a cellular ...

Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. This method combines expression of proteins tagged with the fluorescent non-canonical amino acid ANAP, and FRET between ANAP and fluorescent (trinitrophenyl) nucleotide derivatives. We present examples of nucleotide binding to ANAP-tagged KATP ion channels measured in unroofed plasma membranes and excised, inside-out membrane patches under voltage clamp. The latter allows for simultaneous measurements of ligand binding and channel current, a direct readout of protein function. Data treatment and analysis are discussed extensively, along with potential pitfalls and artefacts. This method provides rich mechanistic insights into the ligand-dependent gating of KATP channels and can readily be adapted to the study of other nucleotide-regulated proteins or any receptor for which a suitable fluorescent ligand can be identified.

This protocol presents a method for measuring adenine nucleotide binding to receptors in real time in a cellular environment. Binding is measured as F&#246;rster resonance energy transfer (FRET) between trinitrophenyl nucleotide derivatives and protein labeled with a non-canonical, fluorescent amino acid.

온전한 기능성 막 단백질에 대한 뉴클레오티드 결합을 실시간으로 측정

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. ...

Transverse Sectioning of Mature Rice (Oryza sativa L.) Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

Starch granules (SGs) exhibit different morphologies depending on the plant species, especially in the endosperm of the Poaceae family. Endosperm phenotyping can be used to classify genotypes based on SG morphotype using scanning electron microscopic (SEM) analysis. SGs can be visualized using SEM by slicing through the kernel (pericarp, aleurone layers, and endosperm) and exposing the organellar contents. Current methods require the rice kernel to be embedded in plastic resin and sectioned using a microtome or embedded in a truncated pipette tip and sectioned by hand using a razor blade. The former method requires specialized equipment and is time-consuming, while the latter introduces a new host of problems depending on rice genotype. Chalky rice varieties, particularly, pose a problem for this type of sectioning due to the friable nature of their endosperm tissue. Presented here is a technique for preparing translucent and chalky rice kernel sections for microscopy, requiring only pipette tips and a scalpel blade. Preparing the sections within the confines of a pipette tip prevents rice kernel endosperm from shattering (for translucent or &#8216;vitreous&#8217; phenotypes) and crumbling (for chalky phenotypes). Using this technique, endosperm cell patterning and the structure of intact SGs can be observed.

Transverse Sectioning of Mature Rice Oryza sativa L. Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

This protocol allows for the preparation of transverse sections of cereal seeds (e.g., rice) for the analysis of endosperm and starch granule morphology using scanning electron microscopy.