D-serine/DsdCXA Control of E. coli Uropathogenesis

描述（由申请方提供）：大肠埃希菌是社区获得性尿路感染（UTI）的最常见原因，也是院内UTI和败血症的主要原因。在美国，每年估计有800万医生就诊于UTI，具有显著的相关发病率和费用（> 1，000，000，000美元）。我们验证了致病基因与危及生命的大肠杆菌致病有关的假设。通过比较尿脓毒症大肠杆菌的基因组序列，可以鉴别肾盂肾炎和脓毒症等大肠杆菌肠外感染。coli菌株CFT073与E.大肠杆菌实验室菌株MG 1655或O157：H7菌株EDL 933。我们鉴定了> 300个CFT073特异性基因座。对D-丝氨酸脱氨酶基因（dsdCXA）周围区域的持续研究尤其引人注目。dsdA的等位基因敲除突变体编码D-丝氨酸脱氨酶，在1型菌毛介导的粘附的表达中没有改变，但是在UTI的上升模型中感染的小鼠的膀胱或肾脏的定殖中比野生型菌株更具300倍的竞争力。DsdC是dsdXA转录的正效应子，并且是lysR调节子家族的成员。通过体内和体外基因表达技术，我们将测试以下假设：D-丝氨酸通过与dsdC或其他协同效应物的相互作用影响直接影响小鼠疾病模型中CFT073发病机制的多个基因的表达。我们还将确定影响dsdCXA基因表达的环境条件和其他基因。两个这样的候选基因是ipuAB（尿路病原体的整合酶样蛋白），其紧邻CFT073以及其它尿路病原性大肠杆菌染色体中的dsdCXA基因。杆菌ipuAB是1型皮利相位开关重组酶fimB和fimE的同源物，fimB和fimE与大肠杆菌连接并控制大肠杆菌的表达。大肠杆菌1型菌毛操纵子。我们将测试的假设，这些基因提供了一个额外的相位开关系统，控制dsdCXA或其他未知基因的表达。本项目的目的是鉴定和鉴定大肠杆菌的关键毒力基因。大肠杆菌与严重的人类疾病有关。这些信息将用于开发新的化疗和疫苗策略。

DESCRIPTION (provided by applicant): Escherichia coli is the most common cause of community acquired urinary tract infection (UTI) and a leading cause of nosocomial UTIs and sepsis. There are an estimated 8 million physician visits per year in the U.S for UTIs with significant associated morbidity and expense (> $1,000,000,000). We tested the hypothesis that virulence genes responsible for the pathogenesis of life-threatening E. coli extraintestinal infections, such as pyelonephritis and sepsis can be identified by comparison of the genome sequence of urosepsis E. coli strain CFT073 to either E. coli laboratory strain MG1655 or O157:H7 strain EDL933. We identified >300 CFT073-specific loci. The continued study of the region surrounding the D-serine deaminase genes (dsdCXA) is especially compelling. An allelic knockout mutant of dsdA, that encodes D-serine deaminase, is unaltered in expression of type 1 pili-mediated adherence, but 300-fold more competitive than the wild type strain in colonizing the bladder or kidney of mice infected in an ascending model of UTI. DsdC is a positive effector of dsdXA transcription and a member of the lysR-family of regulators. By in vivo and in vitro gene expression techniques we will test the hypotheses that D-serine through interaction with either dsdC or other co-effectors affects expression of multiple genes that directly influence CFT073 pathogenesis in murine models of disease. We will also identify environmental conditions and additional genes that affect the expression of the dsdCXA genes. Two such gene candidates are ipuAB (integrase-like proteins of uropathogens) that are immediately adjacent to the dsdCXA genes in the chromosome of CFT073 as well as other uropathogenic E. coli. ipuAB are homologs of the type 1 pili phase-switch recombinases, fimB and fimE that are linked to and control expression of the E. coli type 1 pilus fim operon. We will test the hypothesis that these genes provide an additional phase-switch system that controls expression of dsdCXA or other unknown genes. The objective of the proposed project is to identify and characterize critical virulence genes for E. coli involved in serious human diseases. This information will be of use for the development of new chemotherapeutic and vaccine strategies.