D-serine/DsdCXA control of E. coli uropathogenesis

大肠埃希氏菌是社区获得性尿路感染的最常见原因 尿路感染(UTI)和院内尿路感染和败血症的主要原因。我们关注的是一种基因 大肠杆菌尿毒症株CFT073中的argW岛，该菌含有D-CXA基因 丝氨酸利用和I型菌毛fimBE的ipuAB同系物 重组酶。缺乏D-丝氨酸脱氨酶的CFT073 dsdA突变株是 比野生型CFT073更具竞争力的膀胱或肾脏定植实验 受感染的小鼠。与CFT073相比，分别有44和41个基因表达上调和下调。 在小鼠尿路感染过程中受CFT073 dsdA突变体的调控。上调的基因编码P 以及F1C菌毛、溶血素、OmpF、二肽转运体DPPA和几个与 未知函数。CFT073和其他致尿性大肠杆菌显示(+)趋化性 对D-丝氨酸，而不是L-丝氨酸，如大肠杆菌K-12的情况。IpuA具有类似FIMB的开关 以及在小鼠尿路感染过程中的开关活动。A CFT073 dsdA：：Lacz 转录融合经历了可逆的相转换，尽管是由一种不明原因的 受ipuA和iPub突变影响的机制。Ipua和ipub还控制着一个FIMS- 一组编码分泌产物的基因的独立可逆相变 包括溶血素。因此，我们的原始假设得到了强有力的支持 D-丝氨酸是调控CFT073毒力基因的重要信号， 尿路中的生长和dsdCXA连接的重组酶介导的相态 除1型菌毛外，重要的尿毒力和适合性因素的调节。我们会 探讨细胞内D-丝氨酸升高导致肌动蛋白表达上调的机制 尿毒力和适合性基因，并确定除FIMs外的其他基因 重组酶。我们将使用CFT073 dsdA突变体作为DsdA关闭状态的模型 目的：研究P菌毛和溶血素在小鼠膀胱壁定植中的作用。 肾脏。本课题的目的是鉴定和鉴定大肠杆菌的毒力基因。 与严重的人类疾病有关。这项工作将有助于开发新的疫苗和 抗菌剂。为此，我们最近获得的证据表明，D-丝氨酸 脱氨酶可以作为一种新的药物靶点来鉴定新的抗菌剂。

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.