SecB-like chaperone controls a toxin–antitoxin stress-responsive system in Mycobacterium tuberculosis
結(jié)核分支桿菌中SecB類似的分子伴侶調(diào)控一個(gè)毒素-抗毒素脅迫反應(yīng)性系統(tǒng)
towersimper 譯
SecB-like chaperone controls a toxin–antitoxin stress-responsive system in Mycobacterium tuberculosis 于2011年5月2日發(fā)布在PNAS雜志網(wǎng)絡(luò)上,。
細(xì)菌新合成的蛋白前體在生物產(chǎn)生過(guò)程中一個(gè)重要的步驟就是將它們運(yùn)輸?shù)絻?nèi)膜的Sec轉(zhuǎn)位子(translocon，也稱為轉(zhuǎn)位酶,translocase),。在革蘭氏陰性細(xì)菌中,，分子伴侶SecB結(jié)合到蛋白前體的非天然形式(nonnative forms)，特異性地將它們轉(zhuǎn)移到轉(zhuǎn)位酶的動(dòng)力組分SecA,，從而促進(jìn)它們輸出,。
一個(gè)主要的人類致病菌結(jié)核分支桿菌(Mycobacterium tuberculosis)是一個(gè)不同尋常的革蘭氏陽(yáng)性細(xì)菌，具有明確的外膜和外膜蛋白,。在這個(gè)細(xì)菌中,，輔助前體蛋白的分子伴侶依然還未被搜尋到。本文,，研究人員證實(shí)結(jié)核分支桿菌中未被定義描述的Rv1957基因能夠替換大腸桿菌(Escherichia coli)中的SecB功能,，阻止體外前體蛋白(preprotein)聚集,。有意思地說(shuō),，在結(jié)核分支桿菌中，Rv1957與一個(gè)功能性的脅迫反應(yīng)性(stress-responsive)的higB-higA毒素-抗毒素(toxin-antitoxin,TA)位點(diǎn)簇集在一起,，盡管該位點(diǎn)的功能還不明確,。進(jìn)一步的大腸桿菌和沒(méi)有TA-分子伴侶位點(diǎn)的海分枝桿菌(Mycobacterium marinum)體內(nèi)實(shí)驗(yàn)表明當(dāng)抗毒素和分子伴侶聯(lián)合表達(dá)時(shí),，該毒素的嚴(yán)重毒性被完全抑制。研究人員還發(fā)現(xiàn)Rv1957通過(guò)阻止抗毒素聚集和降解直接作用在抗毒素上,。
歸納在一起,，這些研究結(jié)果表明SecB類似的分子伴侶Rv1957特異性地調(diào)控一個(gè)脅迫反應(yīng)性的TA系統(tǒng)，該系統(tǒng)與結(jié)核分支桿菌的適應(yīng)性反應(yīng)相關(guān),。\\生命科學(xué)論壇\\ towersimper
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生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1101189108
SecB-like chaperone controls a toxin–antitoxin stress-responsive system in Mycobacterium tuberculosis
Patricia Bordes, Anne-Marie Cirinesi, Roy Ummels, Ambre Sala, Samer Sakr, Wilbert Bitter, and Pierre Genevaux
Edited by Linda L. Randall, University of Missouri, Columbia, MO, and approved April 12, 2011 (received for review January 22, 2011)
[Abstract]
A major step in the biogenesis of newly synthesized precursor proteins in bacteria is their targeting to the Sec translocon at the inner membrane. In Gram-negative bacteria, the chaperone SecB binds nonnative forms of precursors and specifically transfers them to the SecA motor component of the translocase, thus facilitating their export. The major human pathogen Mycobacterium tuberculosis is an unusual Gram-positive bacterium with a well-defined outer membrane and outer membrane proteins. Assistance to precursor proteins by chaperones in this bacterium remains largely unexplored. Here we show that the product of the previously uncharacterized Rv1957 gene of M. tuberculosis can substitute for SecB functions in Escherichia coli and prevent preprotein aggregation in vitro. Interestingly, in M. tuberculosis, Rv1957 is clustered with a functional stress-responsive higB-higA toxin–antitoxin (TA) locus of unknown function. Further in vivo experiments in E. coli and in Mycobacterium marinum strains that do not possess the TA-chaperone locus show that the severe toxicity of the toxin was entirely inhibited when the antitoxin and the chaperone were jointly expressed. We found that Rv1957 acts directly on the antitoxin by preventing its aggregation and protecting it from degradation. Taken together, our results show that the SecB-like chaperone Rv1957 specifically controls a stress-responsive TA system relevant for M. tuberculosis adaptive response.(http://www.pnas.org/content/early/2011/04/27/1101189108.abstract)
