共查询到20条相似文献，搜索用时 31 毫秒
1.
Kim S Malinverni JC Sliz P Silhavy TJ Harrison SC Kahne D 《Science (New York, N.Y.)》2007,317(5840):961-964
Integral beta-barrel proteins are found in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. The machine that assembles these proteins contains an integral membrane protein, called YaeT in Escherichia coli, which has one or more polypeptide transport-associated (POTRA) domains. The crystal structure of a periplasmic fragment of YaeT reveals the POTRA domain fold and suggests a model for how POTRA domains can bind different peptide sequences, as required for a machine that handles numerous beta-barrel protein precursors. Analysis of POTRA domain deletions shows which are essential and provides a view of the spatial organization of this assembly machine. 相似文献
2.
Miled N Yan Y Hon WC Perisic O Zvelebil M Inbar Y Schneidman-Duhovny D Wolfson HJ Backer JM Williams RL 《Science (New York, N.Y.)》2007,317(5835):239-242
Many human cancers involve up-regulation of the phosphoinositide 3-kinase PI3Kalpha, with oncogenic mutations identified in both the p110alpha catalytic and the p85alpha regulatory subunits. We used crystallographic and biochemical approaches to gain insight into activating mutations in two noncatalytic p110alpha domains-the adaptor-binding and the helical domains. A structure of the adaptor-binding domain of p110alpha in a complex with the p85alpha inter-Src homology 2 (inter-SH2) domain shows that oncogenic mutations in the adaptor-binding domain are not at the inter-SH2 interface but in a polar surface patch that is a plausible docking site for other domains in the holo p110/p85 complex. We also examined helical domain mutations and found that the Glu545 to Lys545 (E545K) oncogenic mutant disrupts an inhibitory charge-charge interaction with the p85 N-terminal SH2 domain. These studies extend our understanding of the architecture of PI3Ks and provide insight into how two classes of mutations that cause a gain in function can lead to cancer. 相似文献
3.
Gu L Geders TW Wang B Gerwick WH Håkansson K Smith JL Sherman DH 《Science (New York, N.Y.)》2007,318(5852):970-974
An unexpected biochemical strategy for chain initiation is described for the loading module of the polyketide synthase of curacin A, an anticancer lead derived from the marine cyanobacterium Lyngbya majuscula. A central GCN5-related N-acetyltransferase (GNAT) domain bears bifunctional decarboxylase/S-acetyltransferase activity, both unprecedented for the GNAT superfamily. A CurA loading tridomain, consisting of an adaptor domain, the GNAT domain, and an acyl carrier protein, was assessed biochemically, revealing that a domain showing homology to GNAT (GNAT(L)) catalyzes (i) decarboxylation of malonyl-coenzyme A (malonyl-CoA) to acetyl-CoA and (ii) direct S-acetyl transfer from acetyl-CoA to load an adjacent acyl carrier protein domain (ACP(L)). Moreover, the N-terminal adapter domain was shown to facilitate acetyl-group transfer. Crystal structures of GNAT(L) were solved at 1.95 angstroms (ligand-free form) and 2.75 angstroms (acyl-CoA complex), showing distinct substrate tunnels for acyl-CoA and holo-ACP(L) binding. Modeling and site-directed mutagenesis experiments demonstrated that histidine-389 and threonine-355, at the convergence of the CoA and ACP tunnels, participate in malonyl-CoA decarboxylation but not in acetyl-group transfer. Decarboxylation precedes acetyl-group transfer, leading to acetyl-ACP(L) as the key curacin A starter unit. 相似文献
4.
Eshaghi S Niegowski D Kohl A Martinez Molina D Lesley SA Nordlund P 《Science (New York, N.Y.)》2006,313(5785):354-357
CorA family members are ubiquitously distributed transporters of divalent metal cations and are considered to be the primary Mg2+ transporter of Bacteria and Archaea. We have determined a 2.9 angstrom resolution structure of CorA from Thermotoga maritima that reveals a pentameric cone-shaped protein. Two potential regulatory metal binding sites are found in the N-terminal domain that bind both Mg2+ and Co2+. The structure of CorA supports an efflux system involving dehydration and rehydration of divalent metal ions potentially mediated by a ring of conserved aspartate residues at the cytoplasmic entrance and a carbonyl funnel at the periplasmic side of the pore. 相似文献
5.
[目的]克隆和表达嗜酸乳杆菌S-层蛋白基因,用其构建能承载外源抗原表位的乳酸菌细胞表面展示系统。[方法]以染色体DNA为模板克隆S-层蛋白基因SlpA,通过酶切、连接将其插入大肠杆菌-乳酸菌穿梭表达载体pW425et,构建表面展示系统pW425et-S,并对酶切位点进行分析。[结果]将pW425et-S转化入thyA基因缺陷型E.coli X13感受态细胞,SDS-PAGE、Western-blotting、全细胞ELISA检测表明,在重组菌表面表达出S-层蛋白,构建出表面展示系统,确定BstEⅡ作为融合外源保护性抗原基因的酶切位点。[结论]克隆出嗜酸乳杆菌S-层蛋白基因,成功构建表面展示系统pW425et-S,为开发乳酸菌活载体口服活菌疫苗提供了可行性操作平台。 相似文献
6.
Pizarro JC Vulliez-Le Normand B Chesne-Seck ML Collins CR Withers-Martinez C Hackett F Blackman MJ Faber BW Remarque EJ Kocken CH Thomas AW Bentley GA 《Science (New York, N.Y.)》2005,308(5720):408-411
Apical membrane antigen 1 from Plasmodium is a leading malaria vaccine candidate. The protein is essential for host-cell invasion, but its molecular function is unknown. The crystal structure of the three domains comprising the ectoplasmic region of the antigen from P. vivax, solved at 1.8 angstrom resolution, shows that domains I and II belong to the PAN motif, which defines a superfamily of protein folds implicated in receptor binding. We also mapped the epitope of an invasion-inhibitory monoclonal antibody specific for the P. falciparum ortholog and modeled this to the structure. The location of the epitope and current knowledge on structure-function correlations for PAN domains together suggest a receptor-binding role during invasion in which domain II plays a critical part. These results are likely to aid vaccine and drug design. 相似文献
7.
为研究缢蛏C型凝集素基因ScCTL-2的结构和功能特点,克隆了该基因的全长序列,并对其mRNA的表达模式以及重组蛋白的凝菌活性进行研究。结果显示,ScCTL-2的cDNA全长2 194 bp,共编码630个氨基酸,其氨基酸序列拥有4个C型凝集素糖识别结构域和1个N端跨膜区,这一特殊的序列结构不同于任何一种已知的C型凝集素。基因mRNA在健康缢蛏肝胰腺中的表达量显著高于其他组织,在鳃中的表达量次之,而在其余组织中的表达量没有显著性差异;金黄色葡萄球菌与鳗弧菌感染能够显著上调ScCTL-2在缢蛏血细胞中的表达。ScCTL-2的重组蛋白凝菌实验显示:在Ca~(2+)存在的情况下,rScCTL-2能够对实验所采用的金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌、藤黄微球菌和酿酒酵母均产生明显的凝集反应;当溶液中不存在Ca~(2+)时,凝集反应几乎不能发生,意味着rScCTL-2的凝菌活性是严格Ca~(2+)依赖的。研究表明,ScCTL-2可能是一种新的无脊椎动物C型凝集素类型,它具有无脊椎动物C型凝集素普遍具备的免疫活性,可能在缢蛏的免疫中具有重要作用。 相似文献
8.
家蚕五龄幼虫中部丝腺细胞的蛋白质组成比较 总被引：16，自引：2，他引：16
对家蚕5龄期中部丝腺细胞不同区段的蛋白质组成研究，有利于发现与丝胶蛋白合成和分泌有关的功能蛋白质。本研究采用蛋白质双向电泳和图像分析技术，发现家蚕中部丝腺前、中、后3个不同区段的细胞的蛋白质组成具有显著差异；仅在前段表达的20个特异性蛋白质，可能与Ser2A、Ser2B、S4和S5这4种丝胶蛋白的合成与分泌有关；仅在中段表达的22个特异性蛋白质，可能与Ser1B、Ser1C、Ser1D和S3这4种丝胶蛋白的合成与分泌有关；仅在后段表达的27个特异性蛋白质，可能与Ser1A和S3这2种丝胶蛋白的合成与分泌有关。另外，在中段和后段表达、前段不表达的51个差异性蛋白质、表达量在中段和后段比在前段高的20个差异性蛋白质，可能参与了中、后段相应的丝胶蛋白的合成。 相似文献
9.
金属离子在小麦生长过程中起重要作用,但土壤中金属离子含量过高,会对小麦生长造成损害。锌铁转运蛋白ZIP家族(ZRT,IRT-like protein,ZIP)广泛存在于植物中,参与多种金属离子的转运,也能提高植物的耐盐性。利用同源克隆技术获得 AtZTP29在小麦中的同源基因TaZIP29-7B,并获得其启动子序列,利用生物信息学技术对所获得的基因以及启动子序列进行初步分析,预测启动子顺式作用元件,通过实时荧光定量PCR(Quantitative real-time PCR,qRT-PCR)技术分析小麦 TaZIP29-7B基因在根和叶中在不同金属离子溶液处理下的表达情况,以研究该基因在小麦体内中对重金属转运的作用。结果表明:序列分析显示 TaZIP29-7B基因(登录号MK203894)编码277个氨基酸,TaZIP29-7B蛋白为疏水性蛋白,定位在细胞膜上,存在信号肽,属于分泌蛋白,第89～263位置间的结构功能域ZIP,属于典型的ZIP超级家族结构域,具有8个跨膜区;进化分析显示TaZIP29-7B与单子叶植物山羊草(Aegilops tauschii)ZIP29蛋白同源性最高;启动子中存在多种响应胁迫的顺式作用元件;qRT-PCR结果显示,小麦 TaZIP29-7B基因在外界重金属盐的变化下表达量有所变化。说明研究结果为进一步改良小麦抗盐性提供了参考。 相似文献
10.
家蚕谷光甘肽-S-转移酶GSTe3基因的鉴定及其真核表达 总被引：2，自引：1，他引：1
【目的】谷胱甘肽-S-转移酶(Glutathiones S-tansferases,GSTs)是一类由多基因编码的多功能同工酶超家族,在解毒内源和外源性有毒物质中起着重要作用,家蚕GSTs的研究,可为解析家蚕解毒机制奠定基础。【方法】利用生物信息学和分子生物学方法克隆和分析家蚕GSTe3(BmGSTe3),利用RT-PCR分析该基因在家蚕体内的表达情况,利用重组杆状病毒真核表达系统在sf9细胞中真核表达BmGSTe3。【结果】在家蚕中克隆了家蚕的GSTe3,该基因由5个外显子与4个内含子组成,外显子总长度为512bp,属于昆虫特异的Epsilon家族。BmGSTe3包含N-末端和C-末端2个结构域,N-末端由β-α-β-α-β-β-α共7个结构基序组成,而C-末端则由5个α螺旋构成,在启动子上游2500bp区域内共发现了15个可能的转录调控元件。BmGSTe3的表达具有较高的组织特异性,它只在家蚕血液和头部表达。BmGSTe3在sf9细胞中表达的BmGSTe3蛋白具有较好的GSTs酶活性。【结论】BmGSTe3属于昆虫特异的Epsilon家族,其蛋白具有较好的GSTs酶活性。 相似文献
11.
TST为典型膜结合蛋白,具有高度保守序列,广泛存在于植物组织和细胞中。文章根据NCBI网站、Phytozomes数据库和MEGA软件分析大豆基因组中TST同源基因生物信息,发现大豆相关数据库中有8个大豆TST相关基因拷贝,其中5个TST基因与拟南芥和甜菜亲缘关系较近;通过实时荧光定量PCR分析大豆TST基因时空表达模式,确定GmTST2.1基因发挥拷贝作用;克隆GmTST2.1基因并分析其生物信息发现,GmTST2.1蛋白质由734个氨基酸组成,PI为5.1不稳定疏水性蛋白质,二级结构主要由α-螺旋、无规则卷曲和片层结构组成,有典型N端跨膜结构域-中间胞质区-C端跨膜区结构域特征。研究分析GmTST基因生物信息学和表达模式,为进一步验证GmTST基因生物学功能提供借鉴和理论基础。 相似文献
12.
采用转录组测序和荧光定量PCR等方法,分析蔬菜害虫黄曲条跳甲Phyllotreta striolata(Fabrici-us)易化扩散载体超家族成员的cDNA序列及其基因表达。结果表明:黄曲条跳甲的一种易化扩散载体超家族成员PsMFS1,其开放阅读框为1 224bp,编码407个氨基酸,含有2个典型的功能域,即药物分子排出系统蛋白功能域和易化扩散载体超家族蛋白功能域;该基因在黄曲条跳甲雌雄成虫的不同部位中都有表达,其中头部、中肠和精巢或卵巢的相对表达量较高,触角和足部的相对表达量较低。 相似文献
13.
根据葡萄DFR基因CDS序列设计刺葡萄开放阅读框(ORF)特异引物,利用RT-PCR技术克隆获得其DFR基因序列,并通过生物信息学方法分析其生物学特性。结果表明,刺葡萄DFR基因ORF序列全长1 014bp,编码337个氨基酸,命名为Vitis davidii dihydroflavonol 4-reductase gene(VdDFR),GenBank登录号为KF915803。刺葡萄DFR蛋白预测分子量为37 593.2Da,理论等电点pI为5.81,是一个跨膜亲水蛋白,无典型信号肽,不属于分泌蛋白,并且亚细胞定位主要位于细胞质中(70%);二级结构以无规则卷曲为主(52.82%),是一种mixed类蛋白;该蛋白有潜在的7个糖基化位点和16个磷酸化位点,具有NAD(P)结合位点,有NAD依赖型的表异构酶/脱氢酶的N端结构域,属于NADB_Rossmann超家族成员。核苷酸序列分析表明,刺葡萄DFR基因与美丽葡萄、山葡萄和酿酒葡萄的同源性为99%,与圆叶葡萄同源性为98%,与显齿蛇葡萄同源性为94%,进化上比较保守,利用DFR基因编码区碱基序列所建立的系统关系树与真实的植物进化基本一致。 相似文献
14.
采用室温贮藏的方法,研究贮藏时间对大红袍花椒和青花椒品质性状的影响。结果表明,贮藏1、2、3 a时,大红袍花椒果皮麻味素含量和脂肪酸含量降低,分别较对照（当年）降低14.4%、50.8%、69.7.0%和2.0%、10.0%、14.0%,青花椒分别降低11.0%、40.5%、44.2%和6.5%、21.7%、22.8%。种子贮藏1、2、3 a时,大红袍花椒和青花椒脂肪酸含量分别较对照（当年）降低了0.98%、19.6%、20.2%和2.2%、15.3%、22.4%。同时,脂肪酸组分含量受贮藏时间的影响显著。贮藏1 a时,大红袍花椒和青花椒果皮亚麻酸含量分别较对照提高19.2%和26.9%（P＜0.1）,贮藏3 a时,分别减少27.6%和35.8%（P＜0.1）,亚油酸含量分别减少22.2%和15.7%。贮藏1 a的花椒果皮氨基酸含量显著提高,但随时间延长,其含量降低。同时,贮藏1 a时,大红袍花椒果皮中天冬氨酸、脯氨酸、胱氨酸和精氨酸含量分别较对照提高45.2%、55.4%、66.7%、128.6%（P＜0.1）,青花椒果皮中天冬氨酸、谷氨酸、脯氨酸含量分别较对照提高40.8%、30.7%和60.9%（P＜0.1）。室温条件下,花椒保存时间以1 a以内为宜。 相似文献
15.
Huang CH Mandelker D Schmidt-Kittler O Samuels Y Velculescu VE Kinzler KW Vogelstein B Gabelli SB Amzel LM 《Science (New York, N.Y.)》2007,318(5857):1744-1748
PIK3CA, one of the two most frequently mutated oncogenes in human tumors, codes for p110alpha, the catalytic subunit of a phosphatidylinositol 3-kinase, isoform alpha (PI3Kalpha, p110alpha/p85). Here, we report a 3.0 angstrom resolution structure of a complex between p110alpha and a polypeptide containing the p110alpha-binding domains of p85alpha, a protein required for its enzymatic activity. The structure shows that many of the mutations occur at residues lying at the interfaces between p110alpha and p85alpha or between the kinase domain of p110alpha and other domains within the catalytic subunit. Disruptions of these interactions are likely to affect the regulation of kinase activity by p85 or the catalytic activity of the enzyme, respectively. In addition to providing new insights about the structure of PI3Kalpha, these results suggest specific mechanisms for the effect of oncogenic mutations in p110alpha and p85alpha. 相似文献
16.
Insects have an efficient defense system against infections. Their antibacterial immune proteins have been well characterized. However, the molecular mechanisms by which insects recognize foreignness are not yet known. Data are presented showing that hemolin (previously named P4), a bacteria-inducible hemolymph protein of the giant silk moth Hyalophora cecropia, belongs to the immunoglobulin superfamily. Functional analyses indicate that hemolin is one of the first hemolymph components to bind to the bacterial surface, taking part in a protein complex formation that is likely to initiate the immune response. 相似文献
17.
小麦细胞分裂素氧化/脱氢酶基因（TaCKX5）的克隆及其染色体定位 总被引：2，自引：0，他引：2
【目的】克隆小麦的TaCKX基因并对其序列进行生物信息学分析,明确TaCKX基因在小麦基因组中的分布情况,以期为今后深入研究小麦CKX基因以及利用该基因进行小麦重要农艺性状的遗传改良奠定基础。【方法】采用同源克隆结合BAC文库筛选的方法克隆基因,通过小麦缺体-四体对其进行染色体定位。【结果】从普通小麦中国春中分离得到TaCKX5基因的gDNA和cDNA序列。分析表明,TaCKX5基因的开放阅读框为1 596 bp,编码531个氨基酸,含有CKX基因家族典型的功能位点FAD-binding domain,预测属于分泌蛋白,并具有糖基化位点。使用中国春缺体-四体将TaCKX5定位于小麦第三同源群。系统发育分析表明,CKX基因在植物中较为保守,禾谷类作物中直向同源的CKX基因很可能具有相似的特性与功能。【结论】分离获得了普通小麦TaCKX5基因全长,TaCKX5分布于小麦染色体3A、3B、3D上,与水稻OsCKX5基因直向同源。 相似文献
18.
Peter BJ Kent HM Mills IG Vallis Y Butler PJ Evans PR McMahon HT 《Science (New York, N.Y.)》2004,303(5657):495-499
The BAR (Bin/amphiphysin/Rvs) domain is the most conserved feature in amphiphysins from yeast to human and is also found in endophilins and nadrins. We solved the structure of the Drosophila amphiphysin BAR domain. It is a crescent-shaped dimer that binds preferentially to highly curved negatively charged membranes. With its N-terminal amphipathic helix and BAR domain (N-BAR), amphiphysin can drive membrane curvature in vitro and in vivo. The structure is similar to that of arfaptin2, which we find also binds and tubulates membranes. From this, we predict that BAR domains are in many protein families, including sorting nexins, centaurins, and oligophrenins. The universal and minimal BAR domain is a dimerization, membrane-binding, and curvature-sensing module. 相似文献
19.
为研究红鳍东方鲀Takifugu rubripes的性别决定因子(gonadal soma derived factor,GSDF),利用c DNA末端快速扩增技术(RACE)首次克隆了红鳍东方鲀gsdf基因(Trgsdf)的c DNA全长序列(Gen Bank登陆号:KR914667)。结果表明:Trgsdf c DNA序列全长为1734 bp,其中5'端非编码区144 bp,开放阅读框648 bp,3'端非编码区942 bp,共编码215个氨基酸;预测的氨基酸序列中存在1个长度为19个氨基酸的信号肽和相同长度的跨膜区,1个N-糖基化位点NST,1个TGF-β家族成员特有的保守结构域;BLAST同源性分析结果显示,红鳍东方鲀GSDF氨基酸序列与其他鱼类的相似性为26%~58%;系统发育分析结果显示,鱼类GSDF单独聚为一支,与TGF-β超家族内的其他成员分开,红鳍东方鲀与青鳉Oryzias latipes GSDF的亲缘关系最近,先聚为一支,后与三斑海猪鱼Halichoeres trimaculatus聚在一起,与矛尾鱼Latimeria menadoensis的GSDF亲缘关系最远;应用RT-PCR技术检测Trgsdf mRNA在雌性和雄性红鳍东方鲀成鱼不同组织中的表达,结果显示,Trgsdf mRNA在卵巢和精巢中高表达,在皮肤和肌肉组织中微量表达,在其他组织中无表达;采用相对实时荧光定量PCR方法比较了成鱼卵巢和精巢中Trgsdf mRNA的表达量,结果显示,Trgsdf mRNA在精巢中的表达量显著高于卵巢(P0.05),约为卵巢表达量的6倍。研究表明,gsdf基因可能在红鳍东方鲀的性腺尤其是精巢的分化和发育过程中起着重要的作用。 相似文献
20.
细胞凋亡进程中的信号传导途径 总被引：1，自引：0，他引：1
本文对当前生物学的热点研究领域——细胞凋亡过程中所涉及的一些与凋亡相关的信号传导途径做了详尽概述。本文主要介绍了MAPK超家族信号传导途径,Caspases信号传导途径,抑癌基因P53信号传导途径及TNF信号传导途径,这对于阐明肿瘤的发生机制及如何通过特定的信号传导途径调控肿瘤细胞凋亡的进程具有十分重要的理论意义。 相似文献