D-serine/DsdCXA control of E. coli uropathogenesis

D-丝氨酸/DsdCXA 控制大肠杆菌尿路病变

• 批准号: 7577111
• 负责人: Rodney A. Welch
• 金额: $ 34.9万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-06 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7577111
• 关键词: Affect; Bacteria; Bladder; Carbon; Catabolism; Chemotaxis; Clinical; Cytotoxin; D-Serine dehydratase; Development; Dipeptides; Drug Delivery Systems; Escherichia coli; Gene Cluster; Gene Expression; Gene Expression Regulation; Genes; Genetic; Genetic Transcription; Grant; Growth; Hemolysin; Homologous Gene; In Vitro; Island; Kidney; Laboratories; LacZ Genes; Link; Mediating; Modeling; Mus; Mutation; Nitrogen; Peptidoglycan; Phase; Phenotype; Proteins; Regulation; Regulon; Role; Sepsis; Serine; Signal Transduction; Site; Source; System; Testing; Time; Up-Regulation; Urinary tract; Urinary tract infection; Uropathogenic E. coli; Virulence; Work; antimicrobial; cell motility; community-acquired UTI; fimbria; fitness; human disease; in vivo; mutant; nosocomial UTI; novel; novel vaccines; protein expression; public health relevance; recombinase; secretory protein; type 1 fimbriae; uptake

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. 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. PUBLIC HEALTH RELEVANCE: Escherichia coli is the most common cause of community-acquired urinary tract infection (UTI) and a leading cause of nosocomial UTIs and sepsis. 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.

描述（由申请人提供）：大肠杆菌是社区获得性尿路感染 (UTI) 的最常见原因，也是院内尿路感染和败血症的主要原因。我们重点关注大肠杆菌尿脓毒症菌株 CFT073 中 argW 处的遗传岛，该岛包含用于 D-丝氨酸利用的 dsdCXA 基因和 ipuAB（1 型菌毛相开关重组酶 fimBE 的同源物）。缺乏 D-丝氨酸脱氨酶的 CFT073 dsdA 突变体在定植实验感染小鼠的膀胱或肾脏方面的竞争力比野生型 CFT073 强 300 倍。与CFT073相比，在小鼠UTI期间，CFT073 dsdA突变体中分别有44个和41个基因上调和下调。上调基因编码 P 和 F1C 菌毛、溶血素、OmpF、二肽转运蛋白 DppA 以及几个功能未知的基因。 CFT073 以及其他尿路致病性大肠杆菌对 D-丝氨酸表现出 (+) 趋化性，但不像大肠杆菌 K-12 那样对 L-丝氨酸表现出趋化性。 ipuA 在小鼠 UTI 期间具有类似 fimB 的 ON-to-OFF 和 OFF-to-ON fimS 转换活性。 CFT073 dsdA::lacZ 转录融合经历可逆的相转换，尽管是通过受 ipuA 和 ipuB 突变影响的未知机制实现的。 ipuA 和 ipuB 还控制一组编码分泌产物（包括溶血素）的基因的独立于 fimS 的可逆相变。因此，我们为我们最初的假设提供了强有力的支持，即 D-丝氨酸代表了调节 CFT073 毒力基因和泌尿道生长的重要信号，并且 dsdCXA 连接的重组酶介导除 1 型菌毛外的重要尿毒力和适应因子的相态调节。我们将研究细胞内 D-丝氨酸升高导致尿毒力和适应性基因上调的机制，并表征除 fimS 之外由重组酶控制的基因座。我们将使用 CFT073 dsdA 突变体作为 DsdA OFF 状态的模型来研究 P 菌毛和溶血素在小鼠膀胱和肾脏定植中的作用。我们项目的目标是识别和表征与严重人类疾病有关的大肠杆菌的毒力基因。这项工作将有助于开发新的疫苗和抗菌药物。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。公共卫生相关性：大肠杆菌是社区获得性尿路感染 (UTI) 的最常见原因，也是院内尿路感染和败血症的主要原因。我们项目的目标是识别和表征与严重人类疾病有关的大肠杆菌的毒力基因。这项工作将有助于开发新的疫苗和抗菌药物。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。