D-serine/DsdCXA control of E. coli uropathogenesis

大肠埃希菌是社区获得性尿路感染(UTI)的最常见原因 也是医院内尿路感染和败血症的主要原因。在过去的资助期内，我们专注于 含Dserine dsdCXA基因的大肠杆菌尿毒症CFT073株的argW基因岛 利用和ipuAB，fimBE，1型菌毛相开关重组酶的同源物。 缺乏D-丝氨酸脱氨酶的CFT073 dsdA突变体的竞争力是野生型的300倍 CFT073在实验感染小鼠的膀胱或肾脏定植。与.相比 在CFT073 dsdA突变体中，CFT073、44和41基因分别上调和下调 在小鼠尿路感染期间。上调的基因包括D-丝氨酸反应的D-丝氨酸转运体 DsdX，以及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及其他致尿路病原性大肠杆菌 (+)对D-丝氨酸趋化，但不像大肠杆菌K-12那样对L-丝氨酸趋化。IpuA拥有与FIMB类似的功能 小鼠尿路感染过程中的开关和开关活动。CFT073突变体仅与 存在的单个ipuA、FIMB或FIME染色体基因可以从不活动的FIM切换到 能动的脱离表型。IpuA还编码了一种与FIMS无关的可逆相位开关 溶血素表达。一个CFT073 dsdA：：LacZ转录融合经历了可逆的相位切换 虽然受到ipuA和iPuB突变的影响，但机制不明。因此，我们 产生了对我们最初的假设的强烈支持，即D-丝氨酸代表一个重要的信号 用于调节CFT073毒力基因和尿路生长，以及dsdCXA连锁 重组酶介导重要的尿毒力因子的相态调节 类型1菌毛。我们将研究细胞内D-丝氨酸导联升高的机制 为了上调尿毒力基因，除了我们观察到的FIMs外，我们还表征了 利用CFT073 dsdA突变体研究P菌毛的作用 和溶血素在小鼠膀胱和肾脏的定植。我们项目的目标是 鉴定和鉴定与人类严重疾病有关的大肠杆菌毒力基因。这部作品 将有助于开发新的化疗药物和疫苗战略。

Escherichia coli is the most common cause of community-acquired urinary tract infection (UTI) and a leading cause of nosocomial UTIs and sepsis. During the past grant period we focused on a genetic island at argW in E.coli urosepsis strain CFT073 which contains the dsdCXA genes for Dserine 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 included the D-serine-responsive D-serine transporter dsdX, as well as genes for 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. CFT073 mutants with only single ipuA, fimB or fimE chromosomal genes present can switch from nonmotile fimS ON to a motile OFF phenotype. ipuA also encodes a fimS-independent reversible phase switch of hemolysin expression. A CFT073 dsdA::lacZ transcriptional fusion undergoes reversible phaseswitching albeit by an unidentified mechanism affected by ipuA and ipuB mutations. 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 dsdCXAlinked recombinases mediate phase-state regulation of important urovirulence factors besides the type 1 fimbriae. We will investigate the mechanism whereby elevated intracellular D-serine leads to up-regulation of urovirulence genes, characterize loci aside from fimS that we observe are controlled by the recombinases and use the CFT073 dsdA mutant to study the roles 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 in the development of new chemotherapeutic drugs and vaccine strategies.