D-serine/DsdCXA control of E. coli uropathogenesis

描述(申请人提供)：大肠埃希氏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。我们重点研究了大肠杆菌尿毒症菌株CFT073中位于argW的一个基因岛，该岛包含D-丝氨酸利用的dsdCXA基因和fimBE的ipuAB同源物，fimBE是1型菌毛相开关重组酶。缺乏D-丝氨酸脱氨酶的CFT073 dsdA突变体在实验感染的小鼠的膀胱或肾脏定植方面比野生型CFT073具有300倍的竞争力。与CFT073相比，在小鼠尿路感染过程中，CFT073 dsdA突变体中分别有44和41个基因表达上调和下调。上调的基因编码P和F1C菌毛、溶血素、OmpF、二肽转运体DPPA，以及几个功能未知的基因。CFT073和其他致尿路病原性大肠埃希菌对D-丝氨酸表现出趋化作用，而对L-丝氨酸没有表现出与大肠杆菌K-12相同的趋化作用。在小鼠尿路感染过程中，ipuA具有FIMB样的开关和开关开关活动。CFT073 dsdA：：LacZ转录融合经历了可逆的相变，尽管受ipuA和iPuB突变的影响机制不明。IpuA和ipub还控制着一组基因的可逆相变，这些基因编码包括溶血素在内的分泌产物。因此，我们的原始假设得到了强有力的支持，即D-丝氨酸代表着调节CFT073毒力基因和尿路生长的重要信号，并且dsdCXA连锁的重组酶介导了除1型菌毛之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合性基因上调的机制，并确定受重组酶控制的FIM以外的基因座。我们将使用CFT073 dsdA突变体作为DsdA关闭状态的模型，研究P菌毛和溶血素在小鼠膀胱和肾脏定植中的作用。本项目的目标是鉴定和鉴定与人类严重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。公共卫生相关性：大肠埃希氏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。本项目的目标是鉴定和鉴定与人类严重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。

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.