资源描述：
《细菌应激反应 - Shandong University.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、细菌应激反应BacterialStressResponses第七章Maincontent微生物的应激反应定义与分类通用调节途径热休克反应氧压力渗透压蛋白质组学在细菌应激反应研究中的应用BacterialStressResponsesGeneralstressresponseActivationofRpoS(σ38)bycessationofgrowthInductionofPolIV,errorpronepolymeraseHeat-shockresponseActivationofRpoH(σ32),inductionofGr
2、oEGroEprotectsPolVfromdegradationStringentresponseAminoaciddeprivation,starvationMediatedbyguanosinetetraphosphate,ppGppEnhancesRpoHandRpoSresponsesSOSresponseTriggeredbydamagetoDNALexA-RecAmediatedstressresponsesystems细菌多生于动态多变的环境中(温度,pH,压力,氧化,营养,以及各种化学物质刺激等),细菌存在一个
3、整体调控网络可以快速调节大量基因表达来快速适应这种环境变化,这种调控网络被称为stressresponse系统.stressresponsesystems在细菌中高度相似的,有一些在真核细胞和古菌中也是保守的(如热休克反应).不同菌见,激活stressresponse条件不一样1975年O’Farrell2D研究E.coliheat-shockproteins,2003年Hatfield用microarray研究应激反应.基因表达-转录,转录后调控,细菌中转录调控为主.DNA-dependentRNApolymerase,(fiv
4、esubunitsa2bb’w)和anadditionalsubunit(σ).E.coli有7个sigmafactors:σ70andthevegetativesigmafactors,RpoD,RpoN,RpoS,RpoH,RpoF,RpoE,andFecI.这些σ因子通过竞争和RNase核心酶结合,对转录调控起主要租用,另外转录抑制因子,激活因子,σ结合因子,抗σ因子,以及一些小RNAs的调控起辅助作用.RegulationofRpoSExpressionRpoSisinducedduringthetransitionfr
5、omexponentialphasetostationaryphaseorinresponsetovariousstressconditions,引起细胞生理和形态的改变RpoS的表达受严格控制atthetranscriptional,translational,andposttranslationallevelsnlpDFis,aglobaltranscriptionalfactor,inhibitsrpoStranscriptionbydirectlybindingtotherpoSpromoterregion.Fislev
6、elsaregrowth-phasedependent.Attheonsetofstationaryphase,FisdisappearsandthetranscriptionofrpoSisinducedModelforthemechanismofactionofRssBinregulatingSdegradationbyClpXP.RpoS,aMasterRegulatorinStressResponse andAdaptationMorethan10%oftheE.coligenomeiscontrolledbyRpoS,
7、mostofwhichisinvolvedinstressresponse,suchasnutrientlimitationresistancetoDNAdamage,osmoticshockhighhydrostaticpressure,oxidativestress,ethanolresistance,adaptivemutagenesis,acidstress,andbiofilmformation.RpoScontrolsamoredegeneratepromotersequencefeaturinga−10region
8、(TAYACT),Heat-shockresponseInE.coliheat-shockinducespproximately30genesundercontrolofanothersigmafactor,RpoH(32).TheRpoH-regulonisa
