大腸桿菌菌型O157:H7是大腸桿菌的一種腸出血性菌種,，能通過感染小腸上皮層引起嚴(yán)重的胃腸疾病。細(xì)菌效應(yīng)子蛋白EspFu能誘導(dǎo)肌動(dòng)蛋白基座的形成,，后者是細(xì)菌粘附所需要的,。
本期Nature上兩篇相關(guān)的論文闡述了EspFu激發(fā)宿主肌動(dòng)蛋白機(jī)器的機(jī)制,。Sallee等人所做的一項(xiàng)生化分析表明，EspFu能激發(fā)宿主的WASP (Wiscott–Aldrich syndrome protein)肌動(dòng)蛋白成核因子家族,，這些成核因子正常情況下是由GTP酶Cdc42激發(fā)的,。Hui-Chun Chen等人從結(jié)構(gòu)角度進(jìn)行了研究，提供了關(guān)于EspFu 和 N-WASP之間的結(jié)合互動(dòng)及其激發(fā)的詳細(xì)信息,。EspFu模仿N-WASP內(nèi)的一個(gè)自抑制元素來誘導(dǎo)其激發(fā),，導(dǎo)致肌動(dòng)蛋白的組裝。這個(gè)機(jī)制可以確保EspFu專門激發(fā)WASP,，而不是全部Cdc42目標(biāo),。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 454, 1005-1008 (21 August 2008) | doi:10.1038/nature07170
The pathogen protein EspFU hijacks actin polymerization using mimicry and multivalency
Nathan A. Sallee1,2, Gonzalo M. Rivera3, John E. Dueber2,4, Dan Vasilescu3, R. Dyche Mullins2, Bruce J. Mayer3 & Wendell A. Lim2
Enterohaemorrhagic Escherichia coli attaches to the intestine through actin pedestals that are formed when the bacterium injects its protein EspFU (also known as TccP) into host cells1. EspFU potently activates the host WASP (Wiskott–Aldrich syndrome protein) family of actin-nucleating factors, which are normally activated by the GTPase CDC42, among other signalling molecules. Apart from its amino-terminal type III secretion signal, EspFU consists of five-and-a-half 47-amino-acid repeats. Here we show that a 17-residue motif within this EspFU repeat is sufficient for interaction with N-WASP (also known as WASL). Unlike most pathogen proteins that interface with the cytoskeletal machinery, this motif does not mimic natural upstream activators: instead of mimicking an activated state of CDC42, EspFU mimics an autoinhibitory element found within N-WASP. Thus, EspFU activates N-WASP by competitively disrupting the autoinhibited state. By mimicking an internal regulatory element and not the natural activator, EspFU selectively activates only a precise subset of CDC42-activated processes. Although one repeat is able to stimulate actin polymerization, we show that multiple-repeat fragments have notably increased potency. The activities of these EspFU fragments correlate with their ability to coordinate activation of at least two N-WASP proteins. Thus, this pathogen has used a simple autoinhibitory fragment as a component to build a highly effective actin polymerization machine.
