Name: pcr mutagenesis, cloning, expression, fast protein purification protocols and crystallization of the wild type and mutant forms of tryptophan synthase
Uploaded: 2020-09-26T15:00:00.000+00:00
Duration: 9 min 31 s
Description: Watch this Scientific Journal Video about PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase at JoVE

이 작품은 미국 국립 보건원 (GM097569)에 의해 지원되었다.

<ol>
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저자는 공개하고 경쟁 금융 이익을 선언 할 아무것도 없다.

우리는 성공적으로 구조 기능 상관 관계 연구를위한2β2 βQ114A, α2β2 βK167T,α2 β2 βS377A 세인트TS 복합체를 α 돌연변이 형태를 성공적으로 설계했다. 처음에, 우리는 이전 정화 프로토콜을 사용하여 돌연변이를 정화하기 위해 노력했다22,이는 정제 하는 동안 PEG 8000 및 spermine와 α2β2세인트TS 복합 결정?...

트립토판 신타제(TS) 바이엔자임 복합체(α2 β 2)는알로스터 효소로, 박테리아, 식물, 곰팡이1,2,3에서아미노산 L-트립토판의 생합성에서 마지막 두 단계를 촉매한다. 박테리아 살모넬라 장내 세로바 티피무리움 (St)은인간과 다른 동물에서 심각한 위장 감염을 일으킨다. 인간과 더 높은 동물은 TS(EC 4.2.1.20)가 없기 때문에, S. typhimurium α2β2 TS 복합체 (α2β2StTS)의 억제는 크립토스포리디오스및 결핵4,생식기 및 안구 감염5,그리고잠재적인 그녀의 발동을 위한 잠재적 인 약물 대상으로 탐구되었습니다. α 서브유닛은 인돌-3-글리세롤-인산염(IGP)의 알돌리틱 분열을 글리세랄데히드-3-인산염(GAP)과 인돌로 촉매하여, 인돌닌 타우토머 중간체및 그 후 카본-카본 결합 분열의 형성을 통해 GAP및 인돌3,6을생성한다. β 촉매 부위에는 쉬프 베이스를 통해 β-Lys87에 결합된 피리독살 5′-인산염(PLP) 보조 분자가 포함되어 있으며, 이는 효소 β 서브유닛3,7에서반응하는 과정에서 전자 싱크로 기능한다. β 사이트는 L-트립토판과 PLP 의존 반응에서 물 분자를 제공하기 위해 인돌에 의해 L-세린 사이드 체인 하이드록실의 교체를 촉매한다. 세인트 (주) TS는 다효소 복합체2,3내의 기질 채널링 및 알로스터통신을 조사하는 오랜 모델역할을 한다. TS의 α 및 β 서브유닛 간의 양방향 알로스터 통신은 L-트립토판 합성3동안 촉매 단계를 동기화하고 인돌 방출을 방지할 필요가 있다. 이러한 노력을 확장하기 위해, 우리는 여러 돌연변이 (β-Gln114Ala, β-Lys167Thr 및 β-Ser377Ala)를 단일 지점 돌연변이로 제조하여 효소 구조, 메커니즘 및 세인트TS β 서브 유닛의 촉매 부위에서의 관계의 추가 탐구에 사용할 수 있습니다.
α2β2StTS의 촉매 메커니즘에 대한 자세한 연구는 에디스 W. 마일즈의 연구 그룹에 의해 시작되었습니다. 네이티브 대장균 α2 β2 TS 복합체를 통한 초기 연구는 격리된 α 서브유닛8,9,격리된 β 서브유닛10,11 및 α2 β 2TS 단지의 재구성에 초점을 맞추고 있다12. 정제는 황산염 강수량 암모늄, 샘플 투석, DEAE-세바덱스 크로마토그래피, 투석 및 DEAE-Sephadex 컬럼12에대한 제2 크로마토그래피 라운드에 의해 수행되었다. 또 다른 프로토콜에서, 동일한 복합체의 정제는 DEAE-Sephadex 컬럼에 정제된 세포 용재를 적재하고 세파로즈 4B 컬럼, 황산암모늄 강수량 및투석(13)에크로마토그래피 단계를 거쳐 개선되었다. 두 정화 프로토콜모두 4-5일 동안 지속됩니다. 대장균 α2 β2 TS 복합체는 결정화되었지만 그 당시 의결은 X선 회절에 적합하지 않았다.
새로운 연구에서는, 재조합 및 야생형 형태의 S. typhimurium α2β2 TS 복합체는14,15로정결되었다. 재조합 α2β2stTS 복합체는 pEBA-10 발현 벡터를 운반하는 대장균 CB149로 과발현되었다. 초기 결정화 및 X선 회절 데이터 수집 및 분석α2β2StTS 복합체의 분석은14보고되었다. 그러나, α 같은 길고 얇은 바늘2β2세인트TS 크리스탈 구조 연구를 손상. 더 나은 X선 회절 데이터를 수집하기 위해, 또 다른 정화 프로토콜은 α2β2StTS 복합체15의야생 유형 및 돌연변이 형태를 정화하기 위해 설명되었다. 정화는 스퍼민과 PEG 8,000을 사용하여 초기 침전을 명확히 된 세포 용액으로 수행하였고 큰 부피가 큰 침전물을 원심분리에 의해 제거하였다. α 2 β2세인트TS복합체의 높은 양을 포함하는 상주 분획은 황색 결정이 침전될 때까지 4°C에서 16-48h로 저장하였다. 크리스탈은 다른 버퍼에 대해 세척하고 광범위하게 투석되었습니다. 단백질 복합체는 황산암모늄을 함유하는 완충액으로재결정되었고, 투석15. 단백질 결정화는 용액의 단백질 및 침전물 농도에 따라 달라지지만, 용액에서 다른 돌연변이 형태인 α2β2StTS 콤플렉스에 대한 정화를 모니터링, 예측 및 재현하기는 어렵다. 이 프로토콜은 크로마토그래피 방법을 사용하지 않는다는 장점이 있습니다. 그러나, 단점은 결정화, 투석 및 재결정화에 필요한 긴 정화 시간이며, 전형적으로 5-7일이 필요하다. X선 데이터 수집에 적합한 결정을 얻기 위해 600개 이상의 결정화 조건은 단백질 농도, 온도, 강수제(PEG 4,000, 6,000 및 8,000) 및 첨가제(CaCl2,MnCl2,ZnCl2,카다베린, 퍼드린, 퍼드린, 스프레딘, 스프레시네, 스프레딘, 스프레시네,15. 크리스탈은 더 나은 결정 형태를 가지고 있었고 12 % PEG 8,000 및 2 mM 스페민을 포함하는 조건에서 더 빠르게 성장했습니다. 결정화는 4, 30 또는 42°C보다 25°C에서 더 유리했으며3일 15일이내에 최대 치수로 성장하였다. 몇몇α2β 2StTS 결정 구조물은 그 당시 (1996-1999)16,17,18,19,20,21 및 그밖 많은 구조물이 현재까지 간행되었습니다 보고되었습니다.
여기서 주요 목적은 트립토판 신체화를 정화하고 단백질 결정화를 최적화하기 위한 대체 프로토콜을 제시하는 것입니다. 본 작품은 야생형 절연 α 서브유닛(αStTS), 격리된 β 서브유닛(βStTS), α2 β2st TS 복합체, α2 β2StTS 복합체의 야생형 및 돌연변이 형태 를 정화하는 상당한 개선을보여준다. 정제 시간이 현저히 단축되고 결정화 및 극저온 보호가 최적화되었기 때문에 과거의 프로토콜에 비해 이점이 상당합니다. 이 작품에서 설계된 α2β2세인트TS 복합체의 돌연변이 형태는 야생 형 형태에 사용되는 동일한 조건 근처에서 결정화되었습니다. 그러나, 미세 결정화 최적화는 거의 원자 분해능에서 구조 판정을 위한 충분한 품질의 큰 단결정획득이 필요하였다. 현재까지, 단백질 데이터 뱅크(PDB)에 증착된 134개의 트립토판 신체 결정 구조물이 있으며, 각각 101, 31 및 2개의 결정 구조를 각각 박테리아, 고고학 및 진핵생물에 대해 회계합니다. 멋지게, 73 구조는 S. 엔테리카 세로바 티피무륨에 속하고 5 α 의 5 결정 구조2β2세인트TS 단지는 1.50 Angstroms보다 높은 해상도 한계를 가지고있다. 당연히, 4 아웃 5 우리의 연구 그룹에서 준비 되었다 (PDB IDs:5CGQ 에서 1.18 Å, 4HT3 에서 1.30 Å, 4HPJ 에서 1.45 Å, 6DZ4 에서 1.45 Å 해상도). α2β2StTS 복합체의 돌연변이 형태의 정제 된 결정 구조는 L-트립토판 합성에 관련된 필수 아미노산 잔류물이 연주 되는 메커니즘과 역할에 대한 새로운 통찰력을 제공 할 것으로 예상됩니다.

<table><tbody><tr><td>15 mL 10 kDa filter</td><td>MilliporeSigma</td><td>UFC901024</td><td>centrifugal filter unit</td></tr><tr><td>15 mL 100 kDa filter</td><td>MilliporeSigma</td><td>UFC910024</td><td>centrifugal filter unit</td></tr><tr><td>2 mL cryogenic vials</td><td>Corning</td><td>CLS430489</td><td>Cryogenic vials</td></tr><tr><td>2 mL microcentrifuge tubes</td><td>Fisher Scientific</td><td>05-408-141</td><td>microcentrifuge tubes</td></tr><tr><td>24-well Cryschem Plate</td><td>Hampton Research</td><td>HR3-158</td><td>24-well sitting drop plates</td></tr><tr><td>2-mercaptoethanol</td><td>Fisher Scientific</td><td>O3446I-100</td><td>Chemical</td></tr><tr><td>50 mL centrifuge conical tubes</td><td>Thermo Scientific</td><td>12-565-270</td><td>centrifuge conical tubes</td></tr><tr><td>AB15 ACCUMET Basic</td><td>Fisher Scientific</td><td>13-636-AB15</td><td>pH meter</td></tr><tr><td>Agarose</td><td>Fisher Scientific</td><td>BP1356-100</td><td>Agarose gel</td></tr><tr><td>ammonium sulfate</td><td>Fisher Scientific</td><td>A702-500</td><td>Chemical</td></tr><tr><td>Ampicillin</td><td>Fisher Scientific</td><td>BP1760-5</td><td>Antibiotic</td></tr><tr><td>Bacterial incubator</td><td>Fisher Scientific</td><td>S35836</td><td>incubator.</td></tr><tr><td>BamHI</td><td>New England Biolabs</td><td>R0136S</td><td>Restriction enzyme</td></tr><tr><td>bicine</td><td>Fisher Scientific</td><td>BP2646100</td><td>Chemical</td></tr><tr><td>Branson 450 Digital Sonifier</td><td>Brason</td><td>B450</td><td>Cell disruptor</td></tr><tr><td>Cesium chloride</td><td>Fisher Scientific</td><td>BP210-100</td><td>Chemical</td></tr><tr><td>Cesium hydroxide</td><td>Acros Organics</td><td>AC213601000</td><td>Chemical</td></tr><tr><td>Chloramphenicol</td><td>Fisher Scientific</td><td>BP904-100</td><td>Antibiotic</td></tr><tr><td>dimethyl sulfoxide</td><td>Fisher Scientific</td><td>D1391</td><td>Chemical</td></tr><tr><td>dithiothreitol</td><td>Fisher Scientific</td><td>BP172-5</td><td>Chemical</td></tr><tr><td>DNA Polymerase</td><td>Thermo Scientific</td><td>F530S</td><td>HF polymerase</td></tr><tr><td>dNTP Set</td><td>Invitrogen</td><td>10-297-018</td><td>dNTPs set</td></tr><tr><td>EcoRI</td><td>New England Biolabs</td><td>R0101S</td><td>Restriction enzyme</td></tr><tr><td>Ethylenediaminetetraacetic acid</td><td>Fisher Scientific</td><td>S311-100</td><td>Chemical</td></tr><tr><td>Excella E25R Orbital Shaker</td><td>Eppendorf New Brunswick</td><td>M1353-0004</td><td>Orbital incubator</td></tr><tr><td>GE AKTA Prime Plus</td><td>GE Healthcare</td><td>8149-30-0004</td><td>FPLC</td></tr><tr><td>Gel Extraction Kit</td><td>Invitrogen</td><td>K210012</td><td>DNA purification kit</td></tr><tr><td>Glycerol</td><td>Fisher Scientific</td><td>G33-500</td><td>Chemical</td></tr><tr><td>HindIII</td><td>New England Biolabs</td><td>R0104S</td><td>Restriction enzyme</td></tr><tr><td>His-Trap columns</td><td>GE Healthcare</td><td>GE17-5255-01</td><td>5 mL Histrap column</td></tr><tr><td>imidazole</td><td>Fisher Scientific</td><td>O3196-500</td><td>Chemical</td></tr><tr><td>IPTG</td><td>Thermo Fisher Scientific</td><td>R0392</td><td>Inducer</td></tr><tr><td>Kanamycin</td><td>Fisher Scientific</td><td>BP906-5</td><td>Antibiotic</td></tr><tr><td>Kelvinator Series-100</td><td>Kelvinator</td><td>discontinued</td><td>Ultra low freezer</td></tr><tr><td>LB broth</td><td>Fisher Scientific</td><td>BP1426-500</td><td>Liquid broth</td></tr><tr><td>Luria Bertani agar</td><td>Fisher Scientific</td><td>BP1425-2</td><td>Solid broth</td></tr><tr><td>NaCl</td><td>Fisher Scientific</td><td>S271-500</td><td>Chemical</td></tr><tr><td>NcoI</td><td>New England Biolabs</td><td>R0193S</td><td>Restriction enzyme</td></tr><tr><td>Ni-NTA affinity beads</td><td>Thermo Fisher Scientific</td><td>R90115</td><td>Ni-NTA agarose beads</td></tr><tr><td>PEG 8000</td><td>Fisher Scientific</td><td>BP233-100</td><td>Chemical</td></tr><tr><td>phenylmethylsulfonyl fluoride</td><td>Fisher Scientific</td><td>44-865-0</td><td>Chemical</td></tr><tr><td>pyridoxal phosphate</td><td>Acros Organics</td><td>AC228170010</td><td>Chemical</td></tr><tr><td>S-200 HR</td><td>Cytiva</td><td>45-000-196</td><td>Size exclusion column</td></tr><tr><td>SacI</td><td>New England Biolabs</td><td>R0156S</td><td>Restriction enzyme</td></tr><tr><td>Sodium hydroxide</td><td>Fisher Scientific</td><td>S318-100</td><td>Chemical</td></tr><tr><td>Sorvall RC-5B centrifuge</td><td>Sorvall</td><td>8327-30-1004</td><td>Floor cetrifuge</td></tr><tr><td>Spermine</td><td>Acros Organics</td><td>AC132750010</td><td>Chemical</td></tr><tr><td>Superdex 200 prep grade</td><td>Cytiva</td><td>45-002-491</td><td>Size exclusion column</td></tr><tr><td>T4 DNA ligase</td><td>New England Biolabs</td><td>M0202S</td><td>DNA liagse</td></tr><tr><td>Tris</td><td>Fisher Scientific</td><td>BP152-500</td><td>Chemical</td></tr><tr><td>Ubl-specific protease 1</td><td>Thermo Scientific</td><td>12588018</td><td>SUMO Protease</td></tr></tbody></table>

pcr mutagenesis, cloning, expression, fast protein purification protocols and crystallization of the wild type and mutant forms of tryptophan synthase

살모넬라 타이피무륨의 트립토판 신체(TS) 바이엔자임 복합체(α2β2 TS)를 함유한 구조 연구는 촉매 메커니즘, 알로스터식 거동, 그리고 PLP 의존 효소에서 제품에 기판의 효소 변환에 대한 세부 사항을 더 잘 이해하기 위해 수행되었습니다. 이 작품에서, 고립된 α 및 고립된 β 서브유닛을 생성하는 새로운 표현 시스템은 2일 이내에 고립된 서브유닛으로부터 고량의 순수 서브유닛과 α2 β2stTS 콤플렉스의 정화를 허용하였다. 정제는 친화성 크로마토그래피에 의해 수행되었고, 그 다음으로 친화태그, 황산암모늄 강수량 및 크기 배제 크로마토그래피(SEC)의 분열이 뒤따랐다. 효소 β 부위의 주요 잔류물의 역할을 더 잘 이해하기 위해, 현장 직접 돌연변이 발생은 이전 구조 연구에서 수행되었다. 또 다른 프로토콜은 야생 유형과 돌연변이 α2β2세인트TS 단지를 정화하기 위해 만들어졌습니다. 암모늄 황산염 분획 및 SEC를 사용하는 간단하고 빠르고 효율적인 프로토콜은 하루에2β2StTS 단지의 α 정화할 수 있었습니다. 이 작업에 기재된 두 정제 프로토콜은 이전 프로토콜과 비교하여 PEG 8000및 spermine을 사용하여 동일한 복합체를 정화하여 정화 프로토콜을 따라 α2β2stTS 단지를 결정화할 때 상당한 이점이 있다. 야생 유형 및 일부 돌연변이 형태의 결정화는 PEG 8000 및 spermine을 사용하여 일부 돌연변이체의 정제를 손상시키는 약간 다른 조건에서 발생합니다. 엑스레이 결정학 연구에 적합한 결정을 준비하기 위해 결정화, 결정 품질 및 냉동 보호를 최적화하기 위해 몇 가지 노력을기울였습니다. 여기에 제시 된 방법은 일반적으로 트립토판 synthase 서브 유닛과 야생 유형 및 돌연변이 α2β2세인트TS 단지의 정화에 적용해야합니다.

α정화- 및 트립토판 신체의 β서브 유닛 살모넬라 타이피무륨 트립토판 신체의 α-서브유닛(αSt TS)과 β-서브유닛(βStTS)은 수정된 pET SUMO 벡터에서 분리하였다. 도 1A는 His6-SUMO-αStTS(레인 αON) 및 His6-SUMO-βStTS(레인 βON) 융합 단백질에 대응하는 두 개의 강력?...

Watch this Scientific Journal Video about PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase at JoVE

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

이 문서는 살모넬라 타이피무륨 트립토판 synthase의 발현 및 정화를 위한 일련의 연속적인 방법을 제시하며, 이 프로토콜은 하루에 단백질 복합체를 정화하는 신속한 시스템이다. 커버되는 방법은 현장 지향 돌연변이 발생, 대장균의단백질 발현, 친화 성염색로그래피, 젤 여과 크로마토그래피 및 결정화입니다.

PCR 돌연변이 발생, 복제, 발현, 빠른 단백질 정화 프로토콜 및 트립토판 신타제의 야생 유형 및 돌연변이 형태의 결정화

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand ...

pcr-mutagenesis-cloning-expression-fast-protein-purification

Research

JoVE Journal

Biochemistry

4.2K 조회수.  University of California-Riverside. 이 문서는 살모넬라 타이피무륨 트립토판 synthase의 발현 및 정화를 위한 일련의 연속적인 방법을 제시하며, 이 프로토콜은 하루에 단백질 복합체를 정화하는 신속한 시스템이다. 커버되는 방법은 현장 지향 돌연변이 발생, 대장균의단백질 발현, 친화 성염색로그래피, 젤 여과 크로마토그래피 및 결정화입니다.

비디오: PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug used to treat depression and anxiety by binding to the serotonin transporter with high-affinity, blocking serotonin reuptake. Here we report an efficient procedure and a set of tools to stabilize, express, purify, and crystallize serotonin transporter-antibody complexes bound to S-citalopram and other antidepressants. Mutations which stabilize the serotonin transporter were identified using an S-citalopram binding assay. Serotonin transporter expressed in baculovirus-transduced HEK293S GnTI- cells, was reconstituted into proteoliposomes and used to raise high-affinity antibodies. We have developed a strategy to discover antibodies that are useful for structural studies. A straightforward approach for the expression of antibody fragments in Sf9 cells has also been established. Transporter-antibody complexes purified using this procedure are well-behaved and readily crystallize, producing complexes with S-citalopram that diffract X-rays to 3-4 &#197; resolution. The strategies developed here can be utilized to determine the structure of other challenging membrane proteins.

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.

항온, 발현, 정제, 인간 세로토닌 전달체 결정화 바운드<em&gt; S</em&gt; 시탈 로프 람

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug ...

연구

생화학

High Precision FRET at Single-molecule Level for Biomolecule Structure Determination

A protocol on how to perform high-precision interdye distance measurements using F&#246;rster resonance energy transfer (FRET) at the single-molecule level in multiparameter fluorescence detection (MFD) mode is presented here. MFD maximizes the usage of all &#34;dimensions&#34; of fluorescence to reduce photophysical and experimental artifacts and allows for the measurement of interdye distance with an accuracy up to ~1 &#197; in rigid biomolecules. This method was used to identify three conformational states of the ligand-binding domain of the N-methyl-D-aspartate (NMDA) receptor to explain the activation of the receptor upon ligand binding. When comparing the known crystallographic structures with experimental measurements, they agreed within less than 3 &#197; for more dynamic biomolecules. Gathering a set of distance restraints that covers the entire dimensionality of the biomolecules would make it possible to provide a structural model of dynamic biomolecules.

A protocol for high-precision FRET experiments at the single molecule level is presented here. Additionally, this methodology can be used to identify three conformational states in the ligand-binding domain of the N-methyl-D-aspartate (NMDA) receptor. Determining precise distances is the first step towards building structural models based on FRET experiments.

생체 분자 구조 결정을위한 단일 분자 수준의 고정밀 FRET

A protocol on how to perform high-precision interdye distance measurements using F&#246;rster resonance energy transfer (FRET) at the single-molecule ...

Purification and Reconstitution of TRPV1 for Spectroscopic Analysis

Polymodal ion channels transduce multiple stimuli of different natures into allosteric changes; these dynamic conformations are challenging to determine and remain largely unknown. With recent advances in single-particle cryo-electron microscopy (cryo-EM) shedding light on the structural features of agonist binding sites and the activation mechanism of several ion channels, the stage is set for an in-depth dynamic analysis of their gating mechanisms using spectroscopic approaches. Spectroscopic techniques such as electron paramagnetic resonance (EPR) and double electron-electron resonance (DEER) have been mainly restricted to the study of prokaryotic ion channels that can be purified in large quantities. The requirement for large amounts of functional and stable membrane proteins has hampered the study of mammalian ion channels using these approaches. EPR and DEER offer many advantages, including determination of the structure and dynamic changes of mobile protein regions, albeit at low resolution, that might be difficult to obtain by X-ray crystallography or cryo-EM, and monitoring reversible gating transition (i.e., closed, open, sensitized, and desensitized). Here, we provide protocols for obtaining milligrams of functional detergent-solubilized transient receptor potential cation channel subfamily V member 1 (TRPV1) that can be labeled for EPR and DEER spectroscopy.

This article describes specific methods to obtain biochemical quantities of detergent-solubilized TRPV1 for spectroscopic analysis. The combined protocols provide biochemical and biophysical tools that can be adapted to facilitate structural and functional studies for mammalian ion channels in a membrane-controlled environment.

정화 및 분 광 분석에 대 한 TRPV1의 재구성

Polymodal ion channels transduce multiple stimuli of different natures into allosteric changes; these dynamic conformations are challenging to determine ...

A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a single-turnover protease which regulates serum low-density lipoprotein (LDL) levels and, consequently, cardiovascular disease. Although PCSK9 proteolysis is required for its full hypercholesterolemic effect, the evaluation of its proteolytic function is challenging: PCSK9 is only known to cleave itself, undergoes only a single turnover, and after proteolysis, retains its substrate in its active site as an auto-inhibitor. The methods presented here describe an assay which overcomes these challenges. The assay focuses on intermolecular proteolysis in a cell-based context and links successful cleavage to the secreted luciferase activity, which can be easily read out in the conditioned medium. Via sequential steps of mutagenesis, transient transfection, and a luciferase readout, the assay can probe PCSK9 proteolysis under conditions of either genetic or molecular perturbation in a high-throughput manner. This system is well suited for both the biochemical evaluation of clinically discovered missense single-nucleotide polymorphisms (SNPs), as well as for the screening of small-molecule inhibitors of PCSK9 proteolysis.

This protocol presents a method to evaluate the proteolytic activity of an intrinsically low-activity, single turnover protease in a cellular context. Specifically, this method is applied to evaluate the proteolytic activity of PCSK9, a key driver of lipid metabolism whose proteolytic activity is required for its ultimate hypercholesterolemic function.

단일-매출 Protease PCSK9의 베이스를 평가 하는 높은 처리량 Luciferase 분석 결과

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a single-turnover protease which regulates serum low-density lipoprotein (LDL) levels and, ...

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

The M42 aminopeptidases form functionally active complexes made of 12 subunits. Their assembly process appears to be regulated by their metal ion cofactors triggering a dimer-dodecamer transition. Upon metal ion binding, several structural modifications occur in the active site and at the interaction interface, shaping dimers to promote the self-assembly. To observe such modifications, stable oligomers must be isolated prior to structural study. Reported here is a method that allows the purification of stable dodecamers and dimers of TmPep1050, an M42 aminopeptidase of T. maritima, and their structure determination by X-ray crystallography. Dimers were prepared from dodecamers by removing metal ions with a chelating agent. Without their&#160;cofactor, dodecamers became less stable and were fully dissociated upon heating. The oligomeric structures were solved by the straightforward molecular replacement approach. To illustrate the methodology, the structure of a TmPep1050 variant, totally impaired in metal ion binding, is presented showing no further breakdown of dimers to monomers.

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

This protocol has been developed to study the dimer-dodecamer transition of TmPep1050, an M42 aminopeptidase, at the structural level. It is a straightforward pipeline starting from protein purification to X-ray data processing. Crystallogenesis, data set indexation, and molecular replacement have been emphasized through a case of study, TmPep1050H60A H307A variant.

열토가 마리티마 M42 아미노펩티다제 TmPep1050의 올리고메릭 상태 전환을 연구하는 엑스레이 결정학

The M42 aminopeptidases form functionally active complexes made of 12 subunits. Their assembly process appears to be regulated by their metal ion ...

Chemical Modification of the Tryptophan Residue in a Recombinant Ca2+-ATPase N-domain for Studying Tryptophan-ANS FRET

The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that has been crystallized in various conformations. Detailed functional information may nonetheless be obtained from isolated recombinant domains. The engineered (Trp552Leu and Tyr587Trp) recombinant nucleotide-binding domain (N-domain) displays fluorescence quenching upon ligand binding. An extrinsic fluorophore, namely, 8-anilino-1-naphthalene sulfonate (ANS), binds to the nucleotide-binding site via electrostatic and hydrophobic interactions with Arg, His, Ala, Leu, and Phe residues. ANS binding is evidenced by the increase in fluorescence intensity when excited at a wavelength (&#955;) of 370 nm. However, when excited at &#955; of 295 nm, the increase in fluorescence intensity seems to be coupled to the quenching of the N-domain intrinsic fluorescence. Fluorescence spectra display a F&#246;ster resonance energy transfer (FRET)-like pattern, thereby suggesting the presence of a Trp-ANS FRET pair, which appears to be supported by the short distance (~20 &#197;) between Tyr587Trp and ANS. This study describes an analysis of the Trp-ANS FRET pair by Trp chemical modification (and fluorescence quenching) that is mediated by N-bromosuccinimide (NBS). In the chemically modified N-domain, ANS fluorescence increased when excited at a &#955; of 295 nm, similar to when excited at a &#955; of 370 nm. Hence, the NBS-mediated chemical modification of the Trp residue can be used to probe the absence of FRET between Trp and ANS. In the absence of Trp fluorescence, one should not observe an increase in ANS fluorescence. The chemical modification of Trp residues in proteins by NBS may be useful for examining FRET between Trp residues that are close to the bound ANS. This assay will likely also be useful when using other fluorophores.

Chemical Modification of the Tryptophan Residue in a Recombinant Ca2+-ATPase N-domain for Studying Tryptophan-ANS FRET

ANS binds to the Ca2+-ATPase recombinant N-domain. Fluorescence spectra display a FRET-like pattern upon excitation at a wavelength of 295 nm. NBS-mediated chemical modification of Trp quenches the fluorescence of the N-domain, which leads to the absence of energy transfer (FRET) between the Trp residue and ANS.

트립토판-ANS FRET 연구를 위한 재조합 Ca2+-ATPase N-도메인에서 트립토판 잔류물의 화학적 수정

The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that has been crystallized in various conformations. Detailed functional ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

이온 채널의 돌연변이 유발과 기능 분석 Heterologously 포유 동물 세포에 표현

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

생물학

Engineering 'Golden' Fluorescence by Selective Pressure Incorporation of Non-canonical Amino Acids and Protein Analysis by Mass Spectrometry and Fluorescence

Fluorescent proteins are fundamental tools for the life sciences, in particular for fluorescence microscopy of living cells. While wild-type and engineered variants of the green fluorescent protein from Aequorea victoria (avGFP) as well as homologs from other species already cover large parts of the optical spectrum, a spectral gap remains in the near-infrared region, for which avGFP-based fluorophores are not available. Red-shifted fluorescent protein (FP) variants would substantially expand the toolkit for spectral unmixing of multiple molecular species, but the naturally occurring red-shifted FPs derived from corals or sea anemones have lower fluorescence quantum yield and inferior photo-stability compared to the avGFP variants. Further manipulation and possible expansion of the chromophore&#39;s conjugated system towards the far-red spectral region is also limited by the repertoire of 20 canonical amino acids prescribed by the genetic code. To overcome these limitations, synthetic biology can achieve further spectral red-shifting via insertion of non-canonical amino acids into the chromophore triad. We describe the application of SPI to engineer avGFP variants with novel spectral properties. Protein expression is performed in a tryptophan-auxotrophic E. coli strain and by supplementing growth media with suitable indole precursors. Inside the cells, these precursors are converted to the corresponding tryptophan analogs and incorporated into proteins by the ribosomal machinery in response to UGG codons. The replacement of Trp-66 in the enhanced &#34;cyan&#34; variant of avGFP (ECFP) by an electron-donating 4-aminotryptophan results in GdFP featuring a 108 nm Stokes shift and a strongly red-shifted emission maximum (574 nm), while being thermodynamically more stable than its predecessor ECFP. Residue-specific incorporation of the non-canonical amino acid is analyzed by mass spectrometry. The spectroscopic properties of GdFP are characterized by time-resolved fluorescence spectroscopy as one of the valuable applications of genetically encoded FPs in life sciences.

Synthetic biology enables the engineering of proteins with unprecedented properties using the co-translational insertion of non-canonical amino acids. Here, we presented how a spectrally red-shifted variant of a GFP-type fluorophore with novel fluorescence spectroscopic properties, termed &#34;gold&#34; fluorescent protein (GdFP), is produced in E. coli via selective pressure incorporation (SPI).

정식이 아닌 아미노산의 선택적 압력 관에 의해 '황금' 형광 및 질량 분석 및 형광 단백질 분석 엔지니어링

Fluorescent proteins are fundamental tools for the life sciences, in particular for fluorescence microscopy of living cells. While wild-type and ...

생체공학

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident STIM1 regulates the activity of PM Orai1 channels in a process known as store operated calcium (Ca2+) entry which is the principal Ca2+ signaling process that drives the immune response. STIM1 undergoes post-translational N-glycosylation at two luminal Asn sites within the Ca2+ sensing domain of the molecule. However, the biochemical, biophysical, and structure biological effects of N-glycosylated STIM1 were poorly understood until recently due to an inability to readily obtain high levels of homogeneous N-glycosylated protein. Here, we describe the implementation of an in vitro chemical approach which attaches glucose moieties to specific protein sites applicable to understanding the underlying effects of N-glycosylation on protein structure and mechanism. Using solution nuclear magnetic resonance spectroscopy we assess both efficiency of the modification as well as the structural consequences of the glucose attachment with a single sample. This approach can readily be adapted to study the myriad glycosylated proteins found in nature.

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Biochemical and structural analyses of glycosylated proteins require relatively large amounts of homogeneous samples. Here, we present an efficient chemical method for site-specific glycosylation of recombinant proteins purified from bacteria by targeting reactive Cys thiols.

재조합 형 단백질의 생체 외에서 사이트별 Glycosylation에 대 한 대상 시스테인 Thiols

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident ...

면역학 및 감염병학

High-throughput Purification of Affinity-tagged Recombinant Proteins

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further biochemical analyses to obtain detailed insights into structure/function relationships. Advances in oligonucleotide- and gene synthesis technology make large-scale mutagenesis strategies increasingly feasible, including the substitution of target residues by all 19 other amino acids. Gain- or loss-of-function phenotypes then allow systematic conclusions to be drawn, such as the contribution of particular residues to catalytic activity, protein stability and/or protein-protein interaction specificity.
In order to attribute the different phenotypes to the nature of the mutation - rather than to fluctuating experimental conditions - it is vital to purify and analyse the proteins in a controlled and reproducible manner. High-throughput strategies and the automation of manual protocols on robotic liquid-handling platforms have created opportunities to perform such complex molecular biological procedures with little human intervention and minimal error rates1-5.
Here, we present a general method for the purification of His-tagged recombinant proteins in a high-throughput manner. In a recent study, we applied this method to a detailed structure-function investigation of TFIIB, a component of the basal transcription machinery. TFIIB is indispensable for promoter-directed transcription in vitro and is essential for the recruitment of RNA polymerase into a preinitiation complex6-8. TFIIB contains a flexible linker domain that penetrates the active site cleft of RNA polymerase9-11. This linker domain confers two biochemically quantifiable activities on TFIIB, namely (i) the stimulation of the catalytic activity during the 'abortive' stage of transcript initiation, and (ii) an additional contribution to the specific recruitment of RNA polymerase into the preinitiation complex4,5,12 . We exploited the high-throughput purification method to generate single, double and triple substitution and deletions mutations within the TFIIB linker and to subsequently analyse them in functional assays for their stimulation effect on the catalytic activity of RNA polymerase4. Altogether, we generated, purified and analysed 381 mutants - a task which would have been time-consuming and laborious to perform manually. We produced and assayed the proteins in multiplicates which allowed us to appreciate any experimental variations and gave us a clear idea of the reproducibility of our results.
This method serves as a generic protocol for the purification of His-tagged proteins and has been successfully used to purify other recombinant proteins. It is currently optimised for the purification of 24 proteins but can be adapted to purify up to 96 proteins.

We describe a method for the affinity-tagged purification of recombinant proteins using liquid-handling robotics. This method is generally applicable to the small-scale purification of soluble His-tagged proteins in a high-throughput format.

선호도 태그 재조합 단백질의 높은 처리량 정화

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further ...

PCR 돌연변이 발생, 복제, 발현, 빠른 단백질 정화 프로토콜 및 트립토판 신타제의 야생 유형 및 돌연변이 형태의 결정화

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항온, 발현, 정제, 인간 세로토닌 전달체 결정화 바운드