D-serine/DsdCXA control of E. coli uropathogenesis

D-丝氨酸/DsdCXA 控制大肠杆菌尿路病变

基本信息

批准号：
8448312
负责人：
Rodney A. Welch
金额：
$ 29.91万
依托单位：
UNIVERSITY OF WISCONSIN-MADISON
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-06-01 至 2014-01-31
项目状态：
已结题

项目摘要

Escherichia coli is the most common cause of community-acquired urinary tract infection (UTI) and a leading cause of nosocomial UTIs and sepsis. We have focused on a genetic island at argW in E.coli urosepsis strain CFT073 which contains the dsdCXA genes for D- serine utilization and ipuAB, homologs of fimBE, the type 1 fimbriae phase-switch recombinases. A CFT073 dsdA mutant lacking D-serine deaminase is 300-fold more competitive than wild type CFT073 in colonizing the bladder or kidney of experimentally infected mice. Compared to CFT073, 44 and 41 genes were respectively up- and down- regulated in the CFT073 dsdA mutant during murine UTI. Up-regulated genes encoded P and F1C fimbriae, hemolysin, OmpF, a dipeptide transporter DppA, and several genes with unknown functions. CFT073 as well as other uropathogenic E. coli show (+) chemotaxis toward D-serine, but not L-serine as is the case E. coli K-12. ipuA has fimB-like ON-to-OFF and OFF-to-ON fimS switching activity during murine UTI. A CFT073 dsdA::lacZ transcriptional fusion undergoes reversible phase-switching albeit by an unidentified mechanism affected by ipuA and ipuB mutations. ipuA and ipuB also control a fimS- independent reversible phase switch of a set of genes encoding secreted products that includes the hemolysin. Therefore, we generated strong support of our original hypotheses that D-serine represents an important signal for regulation of CFT073 virulence genes and growth in the urinary tract and that the dsdCXA-linked recombinases mediate phase-state regulation of important urovirulence and fitness factors besides the type 1 fimbriae. We will investigate the mechanism whereby elevated intracellular D-serine leads to up-regulation of urovirulence and fitness genes and characterize loci aside from fimS that are controlled by the recombinases. We will use the CFT073 dsdA mutant as a model of the DsdA OFF state to study the roles of P fimbriae and hemolysin in colonization of the murine bladder and kidney. The objective of our project is to identify and characterize virulence genes for E. coli involved in serious human diseases. This work will aid development of new vaccines and antimicrobials. To that end, we have recently acquired evidence that the D-serine deaminase can serve as a novel drug target for identification of new antimicrobials.

大肠杆菌是社区获得性尿路感染的最常见原因（尿路感染）也是院内尿路感染和败血症的主要原因。我们专注于基因尿脓毒大肠杆菌菌株 CFT073 中的 argW 岛包含 D-的 dsdCXA 基因丝氨酸利用和 ipuAB，fimBE（1 型菌毛相开关）的同源物重组酶。缺乏D-丝氨酸脱氨酶的CFT073 dsdA突变体是其300倍在实验性膀胱或肾脏定植方面比野生型 CFT073 有竞争力被感染的老鼠。与CFT073相比，44个和41个基因分别上调和下调在小鼠 UTI 期间，CFT073 dsdA 突变体中受到调节。上调编码 P 的基因和 F1C 菌毛、溶血素、OmpF、二肽转运蛋白 DppA 以及几个带有未知的功能。 CFT073 以及其他泌尿道致病性大肠杆菌表现出 (+) 趋化性朝向 D-丝氨酸，但不像大肠杆菌 K-12 那样朝向 L-丝氨酸。 ipuA 具有类似 fimB 的 ON-to-OFF 以及小鼠尿路感染期间从关闭到开启的 fimS 切换活动。 A CFT073 dsdA::lacZ 转录融合经历了可逆的相转换，尽管是由一个身份不明的机制受 ipuA 和 ipuB 突变影响。 ipuA 和 ipuB 还控制 fimS- 一组编码分泌产物的基因的独立可逆相开关包括溶血素。因此，我们最初的假设得到了强有力的支持 D-丝氨酸是调节 CFT073 毒力基因的重要信号，泌尿道中的生长以及 dsdCXA 连接的重组酶介导相态除 1 型菌毛外，还调节重要的尿毒力和健康因素。我们将研究细胞内 D-丝氨酸升高导致 D-丝氨酸上调的机制尿毒力和适应性基因，并表征除 fimS 之外的基因座，这些基因座受以下因素控制重组酶。我们将使用 CFT073 dsdA 突变体作为 DsdA OFF 状态的模型研究 P 菌毛和溶血素在小鼠膀胱定植中的作用肾。我们项目的目标是识别和表征大肠杆菌的毒力基因涉及严重的人类疾病。这项工作将有助于开发新疫苗和抗菌剂。为此，我们最近获得的证据表明 D-丝氨酸脱氨酶可以作为鉴定新抗菌药物的新药物靶点。