NALP3富含亮氨酸重复序列结构域识别人细胞周期蛋白H和禽冠状病毒蛋白

 目的：寻找与NALP3富含亮氨酸重复序列（leucine-rich repeat, LRR）结构域相互作用的蛋白质分子。方法：克隆NALP3富含亮氨酸重复序列（NALP3-LRR）结构域的DNA序列并经测序检验。应用酵母双杂交技术,构建以NALP3-LRR结构域为诱饵基因的酵母双杂交载体,对人胚肺cDNA文库进行杂交筛选,经酵母回交实验验证蛋白质在酵母细胞内的相互作用并对阳性克隆的DNA进行序列测定和生物信息学分析。将筛选到的阳性克隆进一步用免疫共沉淀实验验证NALP3-LRR结构域与阳性蛋白之间相互作用的可靠性。结果：成功克隆NALP3-LRR结构域的DNA序列并经测序检验正确。用酵母双杂交技术对人胚肺cDNA文库进行酵母杂交筛选共获得4个阳性克隆。免疫共沉淀实验证实能与NALP3-LRR结构域发生相互作用的阳性蛋白是人细胞周期蛋白H和禽传染性支气管炎病毒株Cal99的ORF1a。结论：NALP3的富含亮氨酸重复序列结构域能与人细胞周期蛋白H和禽冠状病毒蛋白发生相互作用。     

与接头蛋白Bam32相互作用的蛋白分子的鉴定

目的:研究接头蛋白(adaptorprotein)Bam32在B细胞抗原受体(Bcellantigenreceptor,BCR)信号转导级联反应中的作用。方法:以Bam32全序列为诱饵,应用酵母双杂交技术筛选能与Bam32相互作用的蛋白分子,并用293T细胞共转染和免疫共沉淀法加以证实。结果:应用酵母双杂交技术筛选出能与Bam32相互作用的蛋白分子,其中1个出现强阳性反应的克隆编码酪氨酸激酶Lyn。用293T细胞共转染和特异性免疫共沉淀法证实,Bam32可在哺乳动物细胞中与Lyn共沉淀。应用抗磷酸化酪氨酸抗体检测显示,Bam32与Lyn相互作用可导致Bam32磷酸化。结论:Bam32可同Lyn相互作用,导致Bam32磷酸化,这在激活下游产物的级联反应中可能起重要作用。     

酵母双杂交系统筛选GATA-1相互作用蛋白质及功能验证

目的 利用酵母双杂交技术从人脑cDNA文库中筛选与人GATA-1相互作用的蛋白质.方法 从人K562细胞中扩增出全长GATA1基因,设计引物将其3段截断体亚克隆入酵母表达载体pDBLeu中,转化至AH109感受态酵母中,利用酵母双杂交技术筛选人脑cDNA文库中与其相互作用的蛋白质,阳性克隆通过回转及免疫共沉淀试验进行验证,利用3xGATA荧光素酶报告基因对相互作用蛋白质进行功能验证.结果 成功构建出酵母诱饵蛋白表达质粒pDBLeu-GATA1(1),pDBLeu-GATA1(2),pDBLeu-GATA1(3),筛到34个阳性克隆,用生物信息学分析及回转验证得到5个与GATA-1相互作用的候选蛋白,通过免疫共沉淀试验进一步验证,获得3个蛋白质能与GATA-1相互作用,分别是ECSIT,EFEMP1和GPS2.荧光素酶试验表明这3个蛋白质均能对GATA1的转录活性产生影响,证实它们之间的相互作用具有影响GATA1转录的功能.结论 应用酵母双杂交技术及免疫共沉淀试验,从人脑cDNA文库中成功获得3个与GATA-1相互作用并对其转录活性具有调节作用的蛋白质,为研究GATA1蛋白质的功能提供了新的线索.     

原癌基因LMO3相互作用蛋白的筛选及鉴定

目的 通过筛选LMO3的相互作用蛋白,进一步了解LMO3的作用及可能机制.方法:酵母双杂交方法 筛选LMO3相互作用蛋白,并通过酵母结合试验、免疫共沉淀及荧光共定位等进行验证.结果:在初步获得相互作用蛋白CIB的基础上,在酵母中证实了LMO3与CIB的相互作用,并通过酵母结合试验确定了CIB与LMO3的相互作用位点,发...     

HBeAg与CD81分子结合的研究

目的 :研究HBeAg与CD81分子在细胞内、外的相互作用。方法 :应用RT PCR技术 ,从HepG2细胞中扩增CD81全基因 ,并构建重组真核表达载体。将其与pGBKT7 eAg共转染营养缺陷型酵母细胞 ,观察生长情况。应用网织红细胞裂解体外翻译及免疫共沉淀试验 ,进一步验证CD81分子与HBeAg的结合。结果 :经EcoRI和BamHI酶切和DNA序列测定鉴定表明 ,构建的CD81基因的重组表达载体正确。共转染后的酵母细胞在营养缺陷的培养基中生长良好。体外免疫共沉淀试验证实 ,CD81与HBeAg出现沉淀带。结论 :HBeAg与CD81分子在细胞内、外均可结合 ,推测CD81在HBV的致病过程中起着重要的作用     

应用酵母双杂交系统筛选人胃黏膜上皮组织SHIP2的相互作用蛋白

目的通过酵母双杂交系统筛选人胃黏膜上皮组织标准均一化cDNA文库,寻找与含Src同源蛋白2肌醇-5-磷酸酶2(SHIP2)相互作用的蛋白。方法利用酵母双杂交系统,以SHIP2的P1(SH2+5-Ptase)和P2(PRD+SAM)段作为诱饵蛋白,筛选出人胃黏膜上皮组织均一化cDNA文库中与SHIP2相互作用的蛋白,并通过免疫共沉淀法进行验证。结果挑选出39个阳性克隆,经测序比对分析,回复性杂交,免疫共沉淀试验验证,最终确定一个与SHIP2相互作用的蛋白抗增殖蛋白1(prohibitin1/PHB)。结论酵母双杂交系统筛选人胃黏膜上皮组织SHIP2的相互作用蛋白PHB。     

与14-3-3ζ相互作用的蛋白Polo样激酶1的筛选与鉴定

目的:应用酵母双杂交系统筛选与14-3-3ζ相互作用的蛋白,进一步鉴定其与Polo样激酶1(Plk1)相互作用。方法:构建pGBKT7-14-3-3ζ诱饵表达载体,筛选HeLa细胞cDNA文库中与14-3-3ζ相互作用蛋白,进一步通过共转酵母、免疫荧光以及外源性和内源性的细胞免疫共沉淀实验验证两者的相互作用。结果:通过酵母双杂交系统筛选出的阳性相互作用蛋白中包括Plk1,进一步通过共转酵母,外源性和内源性的细胞免疫共沉淀实验证实两者的相互作用,免疫荧光实验证实两者共定位于有丝分裂过程中胞质分裂期的中体。结论:Plk1是高度保守的丝氨酸/苏氨酸蛋白激酶,在中体的成熟,有丝分裂期染色体的分离,胞质分裂以及DNA的损伤应答等环节发挥重要作用,其与14-3-3ζ的相互作用为14-3-3蛋白家族参与有丝分裂(M期)的调控提供了直接证据。     

PDLLM5与α7烟碱乙酰胆碱受体的相互作用及作用位点的研究

目的研究支架蛋白PDLIM5与神经元α7烟碱乙酰胆碱受体(α7nAChR)间的相互作用及其作用位点。方法构建PDLIM5基因及其截短片段原核、真核重组表达载体和构建α7nAChR真核重组表达载体,并在大肠杆菌中表达与纯化相关蛋白。采用GST pull down及免疫共沉淀(CO-IP)方法检测PDLIM5与α7nAChR分子间相互作用及结合位点。结果 GST pull down和CO-IP方法检测结果显示PDLIM5与α7nAChR具有相互作用,且α7nAChR与PDLIM5中的PDZ结构域具有特异的相互作用,但不与PDLIM5中的LIM结构域发生反应。结论 PDLIM5通过其PDZ结构域介导同α7nAChR的相互作用。     

hCDC14A与BRAP2相互作用的初步研究

目的： 筛选hCDC14A(human cell division cycle gene 14A)的相互作用蛋白，探索功能联系。方法： 酵母双杂交筛选hCDC14A的可能相互作用蛋白，Pulldown实验和免疫共沉淀实验验证蛋白质间相互作用，免疫荧光显微镜观察目的基因在细胞中的表达和定位，体内泛素化实验提示可能的相互作用机制。结果： 酵母双杂交筛查到BRAP2(BRCA1 associated protein 2)为hCDC14A的可能相互作用蛋白，两者有共同定位，BRAP2可以增强hCDC14A的泛素化修饰。结论： BRAP2可以与hCDC14A相互作用，可能是hCDC14A的泛素连接酶。     

cDNA cloning and chromosome mapping of the human Fe65 gene: interaction of the conserved cytoplasmic domains of the human beta-amyloid precursor protein and its homologues with the mouse Fe65 protein

Using the yeast two hybrid system, a mouse embryo cDNA library was screened for proteins that interact with the C-terminus of the human beta-amyloid precursor protein (beta PP). A fusion protein was identified that interacts specifically with the cytoplasmic domain of beta PP and does not interact with the beta-amyloid region. The protein encoded by this partial mouse cDNA is identical to the C-terminus of the rat Fe65 protein. This mouse protein also interacts with the homologous C-terminal domains of the mouse amyloid precursor-like proteins, APLP1 and APLP2. These conserved cytoplasmic regions contain a common amino acid motif, Asn-Pro-Thr-Tyr, which has previously been shown to influence both the secretion and internalization of beta PP. Fe65 has been implicated in regulatory and cell signaling mechanisms because it contains two different motifs involved in protein binding, a WW domain (a variant of Src homology 3 domains) and a phosphotyrosine interaction domain (PID). Interestingly, the PID domain binds to the same motif present in the conserved cytoplasmic domains of the beta PP and beta PP-like proteins. RNA analyses reveal that Fe65 is predominantly expressed in brain and in the regions most affected by Alzheimer's disease (AD)-associated neuropathology. The human Fe65 mRNA was cloned from a fetal brain cDNA library. The message encodes a protein of 735 amino acids that is 95% identical to the rat Fe65 protein. The human Fe65 gene was mapped on human metaphase chromosomes to band 11p15 using fluorescence in situ hybridization.      

人血管内皮生长因子受体Flt—l胞外配体结合域的筛选及其结构分析

目的 应用酵母双杂交系统筛选人血管内皮生长因子受体Flt－1胞外最小配合结合域。方法 采用PCR技术,从人胎盘cDNA文库扩增出4个截短的Flt-1cDNA,分别含胞外第2、1、－2、2－3和1－3个loop,构建酵母双杂交系统配合表达质粒,并将pGB59／hVEGF165与pGAD424／Flt-ls两两配对转化酵母菌SFY526。采用滤纸法和液体培养法对阳性克隆进行β－半乳糖苷酶活性分析。结果 Flt－1胞外loop2－3与loop1-3的配体结合能力相关不大,loop1-2的结合力较弱,单独第2个loop无配体结合域－2－3loop,这对研制分子量更小、安全性高的可溶性Flt-1片段,开发其在肿瘤、糖尿病性网膜病变等血管生成相关疾病基因治疗中的应用具有重要的指导意义。     

Multiple interactions among proteins encoded by the mite-transmitted wheat streak mosaic tritimovirus

The genome organization of the mite-transmitted wheat streak mosaic virus (WSMV) appears to parallel that of members of the Potyviridae with monopartite genomes, but there are substantial amino acid dissimilarities with other potyviral polyproteins. To initiate studies on the functions of WSMV-encoded proteins, a protein interaction map was generated using a yeast two-hybrid system. Because the pathway of proteolytic maturation of the WSMV polyprotein has not been experimentally determined, random libraries of WSMV cDNA were made both in DNA-binding domain and activation domain plasmid vectors and introduced into yeast. Sequence analysis of multiple interacting pairs revealed that interactions largely occurred between domains within two groups of proteins. The first involved interactions among nuclear inclusion protein a, nuclear inclusion protein b, and coat protein (CP), and the second involved helper component-proteinase (HC-Pro) and cylindrical inclusion protein (CI). Further immunoblot and deletion mapping analyses of the interactions suggest that subdomains of CI, HC-Pro, and P1 interact with one another. The two-hybrid assay was then performed using full-length genes of CI, HC-Pro, P1, P3, and CP, but no heterologous interactions were detected. In vitro binding assay using glutathione-S-transferase fusion proteins and in vitro translation products, however, revealed mutual interactions among CI, HC-Pro, P1, and P3. The failure to detect interactions between full-length proteins by the two-hybrid assay might be due to adverse effects of expression of viral proteins in yeast cells. The capacity to participate in multiple homomeric and heteromeric molecular interactions is consistent with the pleiotropic nature of many potyviral gene mutants and suggests mechanisms for regulation of various viral processes via a network of viral protein complexes.     

Measles virus protein interactions in yeast: new findings and caveats

Complementary DNA clones of measles virus N, N (S228Q; L229D), Ncore (N1-400), Ntail (N401-525), P, PNT (P1-230), PCT (P231-507), L, MEL (L800-2183) and EL (L1300-2183) were fused in frame downstream of the Gal4 binding domain (BD) or activating domain (AD). All but BD-L, BD-MEL and BD-EL, were detected by western blot, with additional C- and/or N-terminal truncated products in the case of BD-N, and BD-P. BD-P and BD-PNT directly activated the reporter genes, indicating that the PNT domain displays transactivating properties. In yeast two-hybrid assays, PNT and PCT domains bind to Ncore and Ntail domains, respectively, indicating that N and P interact in a head to tail orientation via two independent binding sites. BD-N (S228Q; L229D) and AD-N displayed no or poor interaction with P proteins possibly because they may not be properly folded. L binding site on P lies within the PCT domain, and two PCT binding sites lie within the L1-799 and L800-1300 regions. Thus, N to P and P to L protein interactions in measles virus shared many features with other related Paramyxoviridae. From a human cDNA library, several candidate partners of N protein were identified which all reacted with BD-Ncore, and RNA was found to bridge the N protein with one partner.     

Interaction between human papillomavirus type 5 E2 and polo‐like kinase 1

The E2 protein of the papillomavirus plays an essential role in the viral life cycle. Through a yeast two‐hybrid screening, human polo‐like kinase 1 was found to interact with human papillomavirus type 5 E2. Further characterization identified that the domains responsible for the interaction are the transactivation domain of HPV‐5 E2 and the sequence between the kinase and the polo box domains of Plk1. In vivo, Plk1 and HPV‐5 E2 are colocalized at the nuclear speckles. In the skin epithelium not infected with epidermodysplasia verruciformis associated HPVs, Plk1 is expressed in the stratum basale, indicating that the Plk1–HPV‐5 E2 interaction likely occurs in the keratinocytes at the basal layer of the epithelium upon infection of HPV‐5. Both HPV‐5 E2 and Plk1 also interact with the E2 binding domain of Brd4. The E2 binding domain of Brd4 is phosphorylated by Plk1 in vitro, and this phosphorylation event is blocked by the presence of HPV‐5 E2. Hence, these findings suggest the possibility that the cellular function of Brd4 is de‐regulated by forming a complex with HPV‐5 E2 in the infected epithelial cells. J. Med. Virol. 81:536–544, 2009. © 2009 Wiley‐Liss, Inc.     

Secretion of genetically engineered human/mouse class I antigens

Two soluble, secreted forms of HLA-B7 were engineered by the creation of hybrid human/mouse molecules containing the polymorphic 5' region of the HLA-B7 gene and the secretory 3' region of the mouse Q10d gene. The hybrid, designated F1, is the first construct with only human extracytoplasmic domains, consisting of exons for the leader peptide and the three extracellular domains (alpha 1, alpha 2, alpha 3) of B7 spliced to the exons for the Q10d truncated transmembrane and 3' untranslated (3'UT) sequences. The second construct, designated C2, is similar but has the human alpha 3 replaced by the Q10 alpha 3 domain. Protein product from each construct was best demonstrated after gene transfection into the J27.2 cell line. In particular, secretion of the F1 product proves that the Q10 alpha 3 domain is not necessary for secretion of class I/Q10 hybrids. Moreover, the two soluble B7 forms, which differ only in their alpha 3 domain, are similarly recognized by monoclonal antibodies W6/32 (anti-HLA-ABC), BBM.1 (anti-human beta 2 microglobulin), and allo-B7-antibody, but differentially recognized by monoclonal antibody Q1/28 (anti-HLA class I heavy chain). Production of such soluble hybrid class I molecules in large amounts should allow critical structural and functional studies of these proteins.     

The localization of the binding site(s) on human IgG1 for the Fc receptors on homologous monocytes and heterologous mouse macrophages.

Two different methods, a rosette assay and a direct binding assay, have been employed in an examination of the binding of human IgG1 to mouse macrophages. In both cases, inhibition of IgG binding was demonstrated by Fc (CH2 + CH3 domains) and pFc' (CH3 domains) fragments of human IgG. In a homologous system, the binding of 125I-human IgG to human peripheral-blood monocytes was inhibited by the Fc fragment whereas the pFc' fragment was inactive. Scatchard plot analysis of the binding data from both the heterologous and homologous systems allowed association constants and numbers of receptors per cell to be calculated. A more thorough examination of the possible location of IgG Fc-receptor binding sites was made using less orthodox proteolytic cleavage fragments of IgG. The site on human IgG1 responsible for binding to mouse macrophage Fc receptors was confirmed to be within the CH3 domains. Human IgG1 binding to homologous monocytes was shown, using a dimeric C gamma 2 domain fragment, to be via the CH2 domains, and was dependent on the integrity of the covalent interaction between the C gamma 2 domains at the hinge region.