D-serine/DsdCXA control of E. coli uropathogenesis

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。我们重点研究了大肠杆菌尿脓毒症菌株CFT073的argW基因岛，该基因包含用于D-丝氨酸利用的dsdCXA基因和ipuAB， fimBE的同源基因，fimBE是1型菌毛相开关重组酶。缺乏d -丝氨酸脱氨酶的CFT073 dsdA突变体比野生型CFT073在实验感染小鼠的膀胱或肾脏上的定域竞争力强300倍。与CFT073相比，CFT073 dsdA突变体在小鼠UTI期间分别有44个和41个基因上调和下调。上调的基因编码P和F1C菌毛、溶血素、OmpF、二肽转运体DppA以及一些功能未知的基因。CFT073和其他尿路致病性大肠杆菌对d -丝氨酸表现出（+）趋化性，但与大肠杆菌K-12不同，对l -丝氨酸没有趋化性。在小鼠UTI期间，ipuA具有类似于ffib的ON-to-OFF和OFF-to-ON fimS切换活动。CFT073 dsdA::lacZ转录融合经历了可逆的相位转换，尽管受ipuA和ipuB突变影响的机制尚未确定。ipuA和ipuB还控制着一组基因的不依赖于薄膜的可逆相位开关，这些基因编码包括溶血素在内的分泌产物。因此，我们为我们最初的假设提供了强有力的支持，即d -丝氨酸是CFT073毒力基因调控和尿路生长的重要信号，dsdcxa连接的重组酶介导了除1型菌膜外重要的尿毒力和适应性因子的相态调控。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外由重组酶控制的基因座。我们将以CFT073 dsdA突变体作为dsdA OFF状态的模型，研究P菌膜和溶血素在小鼠膀胱和肾脏定植中的作用。我们项目的目的是鉴定和表征大肠杆菌参与严重人类疾病的毒力基因。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，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，也是院内尿路感染和败血症的主要原因。我们项目的目的是鉴定和表征大肠杆菌参与严重人类疾病的毒力基因。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，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.