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，也是医院内UTI和败血症的主要原因。我们集中于大肠杆菌尿脓毒症菌株CFT 073中argW处的遗传岛，其含有用于D-丝氨酸利用的dsdCXA基因和ipuAB，fimBE的同源物，1型菌毛相位转换重组酶。缺乏D-丝氨酸脱氨酶的CFT 073 dsdA突变体在实验感染小鼠的膀胱或肾脏定殖中的竞争力比野生型CFT 073高300倍。与CFT 073相比，在鼠UTI期间，CFT 073 dsdA突变体中分别有44个和41个基因上调和下调。上调表达的基因编码P和F1 C菌毛、溶血素、OmpF、二肽转运蛋白DppA和一些功能未知的基因。CFT 073以及其它尿路致病性E.大肠杆菌对D-丝氨酸有（+）趋化性，而对L-丝氨酸无趋化性。大肠杆菌K-12。ipuA在鼠UTI期间具有fimB样ON-至-OFF和OFF-至-ON fimS转换活性。CFT 073 dsdA：：lacZ转录融合体经历可逆的相位转换，尽管受到ipuA和ipuB突变影响的未鉴定的机制。ipuA和ipuB还控制一组编码分泌产物（包括溶血素）的基因的fimS非依赖性可逆相位转换。因此，我们产生了强有力的支持，我们原来的假设，即D-丝氨酸代表了一个重要的信号调节CFT 073毒力基因和生长在尿路和dsdCXA连接的重组酶介导的相态调节重要的尿路毒力和健身因素，除了1型菌毛。我们将研究细胞内D-丝氨酸升高导致尿毒力和健身基因上调的机制，并表征由重组酶控制的fimS以外的位点。我们将使用CFT 073 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的定殖中的作用。本研究的目的是鉴定和鉴定大肠杆菌的毒力基因。大肠杆菌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标，用于鉴定新的抗菌剂。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，也是医院内UTI和败血症的主要原因。本研究的目的是鉴定和鉴定大肠杆菌的毒力基因。大肠杆菌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标，用于鉴定新的抗菌剂。

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.