生物谷報(bào)道：人類病原體“結(jié)核分支桿菌”,，利用一個(gè)被稱為ESX-1的蛋白分泌體系輸出能夠中和宿主防衛(wèi)體系的毒性因子。 ESX-1已知在感染早期是產(chǎn)生毒性的關(guān)鍵,，但對(duì)它是怎樣被調(diào)控的人們卻知之甚少?，F(xiàn)在，用一個(gè)小鼠結(jié)核模型所做研究表明,，“結(jié)核分支桿菌”可輸出其自己的啟動(dòng)因子,，即一個(gè)被稱為EspR的、能與DNA相結(jié)合的轉(zhuǎn)錄因子,，后者是ESX-1的一個(gè)正調(diào)控因子,。由于ESX-1分泌的一些蛋白是目前臨床疫苗試驗(yàn)中所用的主要抗原，所以這篇論文對(duì)于疫苗研制有潛在意義,。 （生物谷Bioon.com）
生物谷推薦原始出處：
Nature 454, 717-721 (7 August 2008) | doi:10.1038/nature07219
Secreted transcription factor controls Mycobacterium tuberculosis virulence
Sridharan Raghavan1, Paolo Manzanillo1,2, Kaman Chan1,2, Cole Dovey1 & Jeffery S. Cox1
Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, 600 16th Street, Campus Box 2200, San Francisco, California 94143-2200, USA
These authors contributed equally to this work.
Bacterial pathogens trigger specialized virulence factor secretion systems on encountering host cells. The ESX-1 protein secretion system of Mycobacterium tuberculosis—the causative agent of the human disease tuberculosis—delivers bacterial proteins into host cells during infection and is critical for virulence, but how it is regulated is unknown. Here we show that EspR (also known as Rv3849) is a key regulator of ESX-1 that is required for secretion and virulence in mice. EspR activates transcription of an operon that includes three ESX-1 components, Rv3616c–Rv3614c, whose expression in turn promotes secretion of ESX-1 substrates. EspR directly binds to and activates the Rv3616c–Rv3614c promoter and, unexpectedly, is itself secreted from the bacterial cell by the ESX-1 system that it regulates. Efflux of the DNA-binding regulator results in reduced Rv3616c–Rv3614c transcription, and thus reduced ESX-1 secretion. Our results reveal a direct negative feedback loop that regulates the activity of a secretion system essential for virulence. As the virulence factors secreted by the ESX-1 system are highly antigenic, fine control of secretion may be critical to successful infection.
