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1、Bacterial Stress Responses,盛多红 111019 山东大学微生物技术重点实验室,Main content,微生物的应激反应定义与分类 渗透压 氧 PH 热休克反应 营养 蛋白质组学在细菌应激反应研究中的应用,Bacterial Stress Responses,General stress response Activation of RpoS (38) by cessation of growth Induction of Pol IV, error prone polymerase Heat-shock response Activation of RpoH (3
2、2), induction of GroE GroE protects Pol V from degradation Stringent response Amino acid deprivation, starvation Mediated by guanosine tetraphosphate, ppGpp Enhances RpoH and RpoS responses SOS response Triggered by damage to DNA LexA-RecA mediated,stress response systems,细菌多生于动态多变的环境中(温度,pH,压力,氧化,营
3、养,以及各种化学物质刺激等),细菌存在一个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stress response系统. stress response systems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stress response 条件不一样,1975年OFarrell2D研究E.coli heat-shock proteins,2003年Hateld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-dependent RNA polymerase, (fi
4、ve subunits a2bbw) 和an additional subunit (). E. coli有7个sigma factors: 70 and the vegetative sigma factors, RpoD, RpoN, RpoS, RpoH, RpoF, RpoE, and FecI. 这些因子通过竞争和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, 结合因子, 抗因子,以及一些小RNAs的调控起辅助作用.,Regulation of RpoS Expression,RpoS is induced during the transition fro
5、m exponential phase to stationary phase or in response to various stress conditions,引起细胞生理和形态的改变 RpoS的表达受严格控制at the transcriptional, translational, and posttranslational levels,nlpD,Fis, a global transcriptional factor, inhibits rpoS transcription by directly binding to the rpoS promoter region. Fis
6、 levels are growth-phase dependent. At the onset of stationary phase, Fis disappears and the transcription of rpoS is induced,RpoS, a Master Regulator in Stress Response and Adaptation,More than 10% of the E. coli genome is controlled by RpoS, most of which is involved in stress response, such as nu
7、trient limitation resistance to DNA damage, osmotic shock high hydrostatic pressure, oxidative stress, ethanol resistance, adaptive mutagenesis, acid stress, and biofilm formation. RpoS controls a more degenerate promoter sequence featuring a 10 region (TAYACT),Heat-shock response,In E. coli heat-sh
8、ock induces pproximately 30 genes under control of another sigma factor, RpoH (32). The RpoH-regulon is also induced by unfolded proteins Levels of DNA Pol V are dependent on GroE because the chaperon interacts with the polymerase subunit of PolV and protects it from degradation The groEL/ES operon,
9、 which encodes the molecular chaperone GroE, is an important member of this regulon.,Heat-shock response in bacteria,heat-shock responsive genes have specific sequences in their promoters which replace the common -35 and -10 regions: these promoters are recognized by32 32 is encoded by the rpoH gene
10、. The mRNA is stabilized by heat-shock leading to increased translation. In E. coli heat-shock induces approximately 30 genes under control of another sigma factor, RpoH.,Heat Shock Response in Eukaryotes,also have specific sequences, in this case upstream of heat-shock genes - HSE (Heat Shock Eleme
11、nt) This is bound by (HSF) Heat Shock Factor, trimerizes using a leucine zipper. HSF is phosphorylated as a consequence of heat shock - this activates it and allows transcription to take place from the promoter,ompF基因有ompR产物的高亲和位点 ompC基因有ompR产物的低亲和位点 低渗透压时，ompR基因产物少，只结合高亲和位点，ompF基因表达量升高；高渗透压时，ompR基因
12、产物多，可结合低亲和位点，与ompC基因结合，双向转录，促使ompC基因表达量升高外，反向转录生成micFRNA可与ompF的mRNA结合，阻碍翻译。,Regulation of Translation by Antisense RNA,Fig. B3,Two Component Signal Transduction System and the Regulation of Porin Proteins,When bacteria are subjected to DNA damage about 30 genes are coordinately induced, a reaction known as the “SOS response”.,SOS genes may be induced to some degree under a variety of stressful conditions,
