报告题目：C-di-GMP, PilZ, and Biofilm

报告时间：2012年6月16日14:00点

报告地点：生物药学楼3号楼105会议室

报告人：  周三和 教授

国立中兴大学生物化学研究所

报告人简介：

周三和教授1976年毕业于台北师范大学化学系，获学士学位；1978年在台湾大学获得生物化学硕士学位；1984年在美国西雅图华盛顿大学获化学博士学位。1984-1996年，在华盛顿大学先后任助教，助理教授和副教授。1996年至今，在国立中兴大学任教授，兼任生化研究所所长。周教授实验室的研究方向包括：结构基因组学，蛋白组学，X-光晶体衍射学。周教授在国内外学术期刊上已经发表了100多篇学术论文，获得一系列奖励和荣誉，并担任多个学术期刊的编委。

报告人网页： http://biochem.nchu.edu.tw/wb_teacher02.asp?cno=1&tno=58

摘要：

Bacterial type IV pilus (T4P) is a non-flagellar machinery mediating diverse cellular functions, such as surface motility, biofilm formation and pathogenicity. Recent data indicate that T4P biogenesis is initiated via interaction of a non-canonical type II PilZ protein with the FimX and PilB ATPase under high c-di-GMP concentration. However, molecular details of such interactions remain to be elucidated. We now report the hetero-complex crystal structure between a type II PilZ1028 protein and a FimXEAL from Xcc (Xanthomnas campestris pv. campestris) in the presence of c-di-GMP. We demonstrate that c-di-GMP is indispensable for the stable formation of type II XccPilZ1028- XccFimXEAL complex, which is evidenced by a variety of biophysical methods including ITC and gel filtration chromatography. We also show that binding of type II XccPilZ1028 protein induces dimerization of XccFimXEAL domains via a N-terminal helix swapping to form a (XccPilZ1028)2-(XccFimXEAL-c-di-GMP)2 hetero-tetramer complex. In addition, we also observed considerable flexibility for c-di-GMP, which is demonstrated by the discovery of two novel monomeric structures for c-di-GMP  a "bulged" form in the XccFimXEAL-c-di-GMP complex and an "extended but twisted" form in the XccPilZ1028-XccFimXEAL-c-di-GMP complex. Extensive in vitro studies were further carried out using a series of XccPilZ1028 and XccFimXEAL variants to confirm the unique binding modes of c-di-GMP. Altogether, the results represent an important step toward understanding how T4P function is controlled by c-di-GMP in molecular level.