乙型肝炎病毒全S蛋白结合蛋白基因的筛选

HBV与肝硬化、肝细胞癌的发生发展密切相关[1],通过其表达的病毒蛋白与肝细胞蛋白相互作用导致疾病进展.本研究中,我们对全S基因编码产物功能进行了探讨,并以其为靶蛋白,利用酵母双杂交技术寻找其与肝细胞相互作用的蛋白质,以进一步探讨HBV致病机制.     

蛋白质与蛋白质相互作用研究技术

蛋白质-蛋白质相互作用的研究是蛋白质组学的重要内容，随着研究的深入，促进了研究技术的发展和完善。本文将对研究蛋白质相互作用的技术-酵母双杂交、化学能量共振能量转移、双分子荧光互补技术、荧光能量转移技术、生物分子相互作用分析技术、蛋白质芯片等技术的特点及应用做一综述。     

禽流感病毒NP基因的酵母双杂交饵载体表达及自激活检测

目的构建H5N1亚型禽流感病毒NP基因的酵母双杂交诱饵载体,验证其在酵母中的表达并检测其自激活作用。方法以PCR法从pGEMT/H5NP扩增NP基因编码区序列,将其定向克隆到PGBKT7载体,经测序鉴定后,PEG/Li-Ac法转化酵母菌株AH109,用表型筛选法及颜色筛选法检测其自激活作用同时Westernblot验证诱饵蛋白的表达。结果获得NP编码区基因,并成功构建酵母双杂交系统中的诱饵载体pGBKT7-NP,对宿主细胞酵母菌株AH109无毒性和自激活作用,并能在酵母细胞中稳定表达。结论诱饵载体pGBKT7-NP可用于GAL4酵母双杂交系统钓取与禽流感病毒核蛋白相互作用的蛋白。     

蛋白酪氨酸磷酸酶非受体型12与心脏HERG钾通道相互作用

目的鉴定HERG钾通道的相互作用蛋白,并进一步研究该相互作用蛋白对HERG钾通道的功能调控。方法 (1)应用酵母双杂交技术,构建含有HERG氨基末端的诱饵载体,将转染有诱饵载体的酵母菌AH109与预转染有人类cDNA文库的Y187酵母菌进行双杂交,初步筛选出HERG的相互作用蛋白;(2)应用免疫共沉淀技术进一步验证酵母双杂交所筛选蛋白与HERG之间的相互作用;(3)GSTpull-down分析:应用GST-HERGT-NT融合蛋白和谷光苷肽-琼脂糖4B小球从大鼠心肌裂解物中沉淀蛋白质,应用抗PTPN12抗体对沉淀物进行WesternBlot分析;(4)免疫荧光组织化学分析:应用抗PTPN12和抗HERG的抗体和荧光标记二抗显示PTPN12及HERG的亚细胞定位,应用激光共聚焦显微镜观察。结果 (1)酵母双杂交筛选发现蛋白酪氨酸磷酸酶非受体型12(Proteintyrosinephosphatasenonreceptortype12,PTPN12)与HERG氨基末端存在相互作用;(2)免疫共沉淀分析发现抗HERG的抗体能够沉淀HERG和PTPN12复合物;(3)GSTpull-down分析发现GST-HERG-NT能够将PTPN12沉淀,而GST蛋白则不能沉淀PTPN12;(4)免疫荧光组织化学分析发现PTPN12和HERG两个蛋白共定位的地方主要出现在细胞膜。结论 PTPN12与HERG氨基末端相互作用,这一发现将有助于更加透彻地理解HERG通道特性多样性的分子基础和LQTS的发病机理。     

酵母双杂交系统的原理及应用

0 引言蛋白质和蛋白质的相互作用是很多生命现象的基础。随着分子生物学技术的发展,特别是人类基因组计划的完成,使人类对基因的结构和功能的认识不断加深,但基因编码的蛋白质的功能研究尚是一个难题。酵母双杂交(yeast two hybrid)技术是利用酵母遗传学方法分析蛋白质之间的相互作用,该方法建立以来,经过不断的完善和发展,不但可以检测已知蛋白质之间的相互作用,更重要的在于发现新的与已知蛋白相互作用的未知蛋白。     

柔嫩艾美耳球虫顶膜抗原-1与微线蛋白-2相互作用的鉴定

目的研究柔嫩艾美耳球虫顶膜抗原-1(EtAMA1)与微线蛋白-2(EtMIC2)之间的相互作用。方法以柔嫩艾美耳球虫子孢子cDNA为模板,PCR扩增EtAMA1和EtMIC2基因,构建酵母双杂交诱饵载体pGBKT7-EtAMA1及捕获载体pGADT7-EtMIC2并转化Y2HGold酵母菌中,观察酵母在营养缺陷选择培养基上的生长情况。原核表达GST-EtAMA1和His-EtMIC2融合蛋白,纯化后进行GST-Pulldown试验。同时构建真核表达载体pcDNA3.1-HisEtAMA1和pcDNA3.1-HA-EtMIC2并转染HEK-293T细胞,收集细胞裂解液,进行免疫共沉淀试验。在此基础上构建双分子荧光互补载体pEtAMA1-Myc-LC151和pEtMIC2-HA-KN151并转染HEK-293T细胞,激光共聚焦观察转染细胞荧光发生情况。结果诱饵基因和捕获基因均对酵母双杂交系统无自激活和毒性作用,pGBKT7-EtAMA1/pGADT7-EtMIC2共转化菌能激活酵母双杂交报告系统;原核表达并纯化GST-EtAMA1和His-EtMIC2融合蛋白进行GST-Pulldown试验,二者可在体外相互作用;EtAMA1和EtMIC2可在HEK-293T细胞中共表达,免疫共沉淀试验进一步证实二者间的相互作用;双分子荧光互补技术验证EtAMA1和EtMIC2在细胞内存在相互作用。结论通过酵母双杂交、GST-Pulldown、免疫共沉淀及双分子荧光互补技术验证柔嫩艾美耳球虫顶膜抗-1(EtAMA1)与微线蛋白-2(EtMIC2)之间存在相互作用,这为揭示微线蛋白在鸡球虫入侵宿主细胞过程中的分子机制提供了理论基础。     

酵母双杂交诱饵蛋白LASS1融合表达质粒的构建及鉴定

目的 构建酵母双杂交系统诱饵蛋白大鼠LASS1融合表达质粒,为进一步筛选大鼠脑神经元内与LASS1p相互作用的蛋白奠定基础.方法 应用PCR方法获得大鼠LASS1基因2个片段,分别克隆入酵母双杂交系统诱饵蛋白质粒载体pGBKT7,转染酵母菌AH109并检测重组质粒的自激活现象及毒性.利用Western印迹检测重组质粒在AH109的表达情况.结果 LASS1基因的PCR产物片段大小分别为Flag(111 bp)、Slag(109 bp);Western印迹结果表明2个重组质粒表达的蛋白均可以与抗c-Myc抗体在22 kU处特异性反应;重组质粒转化酵母后无自激活作用.结论 重组质粒pGBKT7-Flag、pGBKT7-Slag均能够在AH109内正确表达,可作为酵母双杂交系统诱饵蛋白使用.     

酵母双杂交诱饵蛋白LASS1合表达质粒的构建及鉴定

目的构建酵母双杂交系统诱饵蛋白大鼠LASS1融合表达质粒，为进一步筛选大鼠脑神经元内与LASS1p相互作用的蛋白奠定基础。方法应用PCR方法获得大鼠LASS1基因2个片段，分别克隆人酵母双杂交系统诱饵蛋白质粒载体pGBKT7，转染酵母菌AH109并检测重组质粒的自激活现象及毒性。利用Western印迹检测重组质粒在AH109的表达情况。结果LASS1基因的PCR产物片段大小分别为Flag（111bp）、Slag（109bp）；Western印迹结果表明2个重组质粒表达的蛋白均可以与抗c-Myc抗体在22ku处特异性反应；重组质粒转化酵母后无自激活作用。结论重组质粒pGBKT7-Flag、pGBKT7-Slag均能够存AH109内正确表达，可作为酵母双杂交系统诱饵蛋白使用。     

乙型肝炎病毒全S蛋白与纤维蛋白原α链的相互作用

目的:筛选人肝细胞cDNA文库中与乙型肝炎病毒(HBV)全S蛋白相互作用蛋白的基因,并反向验证HBV全S蛋白候选结合蛋白之间相互作用.方法:将全S基因定向克隆到酵母表达栽体pDEST 32,构建正向筛选的诱饵质粒并Western b1ot法验证其在酵母中的表达.将诱饵质粒与人肝细胞cDNA文库质粒共同转化MaV203酵母细胞,在人肝细胞cDNA文库筛选候选结合蛋白,提取阳性茵落质粒测序.并分析其生物学性质.将筛选出的纤维蛋白原α链中下游序列及不同全S变异株基因,分别定向克隆到pDEST32及pDEST22载体中,利用Western blot法验证表达.将诱饵质粒与猎物质粒共同转化MaV203酵母细胞,以反向酵母双杂交方法验证初筛结果的可靠性及正确性.结果:正向的酵母双杂交实验,经初筛和再转染实验纤维蛋白原α链可与HBV全S蛋白发生相互作用.再以纤维蛋白原α链为靶基因设计诱饵质粒,以四种变异的HBV全S蛋白为靶基因设计猎物质粒,反向酵母双杂交法证实维蛋白原α链中下游可与不同全S变异体(总差异率2%)发生相互作用,纤维蛋白原α链与全S蛋白的结合域可能为病毒蛋白的前268aa.结论:纤维蛋白原β链中下游可与HBV全S蛋白产生特异性结合,其结合域可能与病毒蛋白的前268aa产生相互作用.     

HCV NS5A结合蛋白顺乌头酸酶1的验证研究

目的筛选人肝脏cDNA文库中与HCV NS5A的结合蛋白基因,验证其中顺乌头酸酶1与HCV NS5A的相互作用。方法应用酵母双杂交系统3筛选人肝脏cDNA文库中的HCV NS5A结合蛋白基因,应用哺乳动物双杂交及免疫共沉淀技术验证其中顺乌头酸酶1蛋白与HCV NS5A之间的相互作用。结果成功筛选出人肝脏cD-NA文库中与HCV NS5A存在相互作用的蛋白基因,哺乳动物双杂交及免疫共沉淀实验结果证实HCV NS5A与顺乌头酸酶1蛋白在HepG2细胞内存在相互作用。结论本实验成功筛选人肝脏cDNA文库中的HCV NS5A结合蛋白基因,并且在体外水平即细胞内证实HCV NS5A与其中的顺乌头酸酶1蛋白之间的相互作用,为进一步细胞内及体内的糖、脂类代谢等功能研究奠定基础。     

Protein-protein interactions with subunits of human nuclear RNase P

A yeast two-hybrid system was used to analyze interactions among the protein subunits of human nuclear RNase P themselves and with other interacting partners encoded in a HeLa cell cDNA library. Subunits hpop1, Rpp21, Rpp29, Rpp30, Rpp38, and Rpp40 are involved in extensive, but weak, protein-protein interactions in the holoenzyme complex. Rpp14, Rpp20, and Rpp30 were found to have strong interactions with proteins encoded in the cDNA library. The small heat shock protein 27, which interacts with Rpp20 in the two-hybrid assay, binds to Rpp20 during affinity chromatography and can be found to be associated with, and enhances the activity of, highly purified RNase P. RNase P activity in HeLa cell nuclei also increases under the stress of heat shock.     

Reverse two-hybrid and one-hybrid systems to detect dissociation of protein-protein and DNA-protein interactions.

Macromolecular interactions define many biological phenomena. Although genetic methods are available to identify novel protein-protein and DNA-protein interactions, no genetic system has thus far been described to identify molecules or mutations that dissociate known interactions. Herein, we describe genetic systems that detect such events in the yeast Saccharomyces cerevisiae. We have engineered yeast strains in which the interaction of two proteins expressed in the context of the two-hybrid system or the interaction between a DNA-binding protein and its binding site in the context of the one-hybrid system is deleterious to growth. Under these conditions, dissociation of the interaction provides a selective growth advantage, thereby facilitating detection. These methods referred to as the "reverse two-hybrid system" and "reverse one-hybrid system" facilitate the study of the structure-function relationships and regulation of protein-protein and DNA-protein interactions. They should also facilitate the selection of dissociator molecules that could be used as therapeutic agents.     

A yeast two-hybrid knockout strain to explore thioredoxin-interacting proteins in vivo

All organisms contain thioredoxin (TRX), a regulatory thiol:disulfide protein that reduces disulfide bonds in target proteins. Unlike animals and yeast, plants contain numerous TRXs for which no function has been assigned in vivo. Recent in vitro proteomic approaches have opened the way to the identification of >100 TRX putative targets, but of which none of the numerous plant TRXs can be specifically associated. In contrast, in vivo methodologies, including classical yeast two-hybrid (Y2H) systems, failed to reveal the expected high number of TRX targets. Here, we developed a yeast strain named CY306 designed to identify TRX targets in vivo by a Y2H approach. CY306 contains a GAL4 reporter system but also carries deletions of endogenous genes encoding cytosolic TRXs (TRX1 and TRX2) that presumably compete with TRXs introduced as bait. We demonstrate here that, in the CY306 strain, yeast TRX1 and TRX2, as well as Arabidopsis TRX introduced as bait, interact with known TRX targets or putative partners such as yeast peroxiredoxins AHP1 and TSA1, whereas the same interactions cannot be detected in classical Y2H strains. Thanks to CY306, we also show that TRXs interact with the phosphoadenosine-5-phosphosulfate (PAPS) reductase MET16 through a conserved cysteine. Moreover, interactions visualized in CY306 are highly specific depending on the TRX and targets tested. CY306 constitutes a relevant genetic system to explore the TRX interactome in vivo and with high specificity, and opens new perspectives in the search for new TRX-interacting proteins by Y2H library screening in organisms with multiple TRXs.     

HEV-Capsid Protein Interacts With Cytochrome P4502C8 and Retinol-Binding Protein 4

Background

Hepatitis E virus (HEV) is a major causative agent of acute clinical hepatitis in adults throughout much of Asia, the Middle East, and Africa. The lack of an efficient cell culture system for HEV has greatly limited our understanding of the mechanisms of infection, replication, and pathogenicity of this virus. The yeast two-hybridization system is considered to be an efficient method for determining protein-protein interactions and screening interactive proteins associated with host cells.

Objectives

In order to identify the host-cell proteins interacting with the HEV-capsid proteins, a fragment of the HEV-capsid protein p239 (amino acids 368–606) was used as bait; human liver cDNA library was used as a source of host-cell proteins, and the screening was performed using the CytoTrap yeast two-hybrid system.

Materials and Methods

The CytoTrap yeast two-hybrid system, which is also called Sos Recruitment System (SRS), was used to analyze the interaction of the p239 fragment with host-cell proteins.

Results

We isolated 2 proteins, cytochrome P4502C8 (CYP4502C8) and retinol-binding protein 4 (RBP4) after 2 rounds of screening. Co-immunoprecipitation assays showed that both the proteins could bind in vitro to the HEV virion in HepG2 cells.

Conclusions

CYP4502C8 and RBP4 screened from liver cDNA library using the CytoTrap yeast two-hybrid system interact with HEV capsid in vitro.     

Screening of hepatocyte proteins binding to F protein of hepatitis C virus by yeast two-hybrid system

AIM: To investigate the biological function of F protein by yeast two-hybrid system. METHODS: We constructed F protein bait plasmid by cloning the gene of F protein into pGBKT7, then recombinant plasmid DNA was transformed into yeast AH109 (a type). The transformed yeast AH 109 was mated with yeast Y187 (a type) containing liver cDNA library plasmid in 2×YPDA medium. Diploid yeast was plated on synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) containing X-α-gal for selection and screening. After extracting and sequencing plasmids from positive (blue) colonies, we underwent sequence analysis by bioinformatics. RESULTS: Thirty-six colonies were selected and sequenced. Among them, 11 colonies were zymogen granule protein, 5 colonies were zinc finger protein, 4 colonies were zinc-α-2-glycoprotein, 1 colony was sialyltransferase, 1 colony was complement control protein factor I, 1 colony was vitronectin, and 2 colonies were new genes with unknown function. CONCLUSION: The yeast two-hybrid system is an effective method for identifying hepatocyte proteins interacting with F protein of hepatitis C virus. F protein may bind to different proteins.     

Studying interactions of four proteins in the yeast two-hybrid system: Structural resemblance of the pVHL/elongin BC/hCUL-2 complex with the ubiquitin ligase complex SKP1/cullin/F-box protein

The yeast two-hybrid system is a powerful technique that detects interactions between two proteins and has been useful in identifying new binding partners. However, the system fails to detect protein-protein interactions that require the presence of additional components of a multisubunit complex. Here we demonstrate that the vector YIpDCE1 can be used to express elongins B and C in yeast, and that these proteins form a stable complex that interacts with the von Hippel-Lindau tumor-suppressor gene product (pVHL). Only when pVHL and elongins B and C (VBC) are present does an interaction with the cullin family member, hCUL-2, occur, forming the heterotetrameric pVHL/elongin BC/hCUL-2 complex. This system was then used to map the binding region of hCUL-2 for the VBC complex. The first amino-terminal 108 aa of hCUL-2 are necessary for interaction with the VBC complex. The elongin BC dimer acts as a bridge between pVHL and hCUL-2 because pVHL and hCUL-2 can form distinct complexes with elongins B and C. These results reveal a striking structural resemblance of pVHL/elongin BC/hCUL-2 complex with the E3-like ubiquitin ligase complex SKP1/Cullin/F-box protein with respect to protein composition and sites of interactions. Thus, it seems possible that pVHL/elongin BC/hCUL-2 complex will possess ubiquitin ligase activity targeting specific proteins for degradation by the proteasome.     

Molecular epidemiological study on pre-X region of hepatitis B virus and identification of hepatocyte proteins interacting with whole-X protein by yeast two-hybrid

AIM: To identify the pre-X region in hepatitis B virus (HBV) genome and to study the relationship between the genotype and the pre-X region. To investigate the biological function of whole-X (pre-X plus X) protein, we performed yeast two-hybrid to screen proteins in liver interacting with whole-X protein. METHODS: The pre-X region of HBV was amplified by polymerase chain reaction (PCR) method, and was cloned to pGEM Teasy vector. After the target region was sequenced, Vector 8.0 software was used to analyze the sequences. The whole-X bait plasmid was constructed by using yeast two-hybrid system 3. Yeast strain AH109 was transformed. After expression of the whole-X protein in AH109 yeast strains was proved, yeast two-hybrid screening was performed by mating AH 109 with Y187 containing liver cDNA library plasmid. The mated yeast was plated on quadruple dropout medium and assayed for α-gal activity. The interaction between whole-X protein and the protein obtained from positive colonies was further confirmed by repeating yeast two-hybrid. After extracting and sequencing of plasmid from blue colonies, we carried out analysis by bioinformatics. RESULTS: After sequencing, 27 of 45 clones (60%) were found encoding the pre-X peptide. Eighteen of twenty-seven clones (66.7%) of pre-X coding sequences were found from genotype C. Five positive colonies that interacted with whole-X protein were obtained and sequenced; namely, fetuin B, UDP glycosyltransferase 1 family-polypeptide A9, mannose-P-dolichol utilization defect 1, fibrinogen-B beta polypeptide, transmembrane 4 superfamily member 4-CD81 (TM4SF4). CONCLUSION: The pre-X gene exists in HBV genome. Genes of proteins interacting with whole-X protein in hepatocytes were successfully cloned. These results brought some new clues for studying the biological functions of whole-X protein.