Analysis of virulence factors in Uropathogenic Escherichia coli

本研究的目的是利用一种特异的DNA探针在致尿路感染的大肠杆菌(UPEC)中寻找霍乱弧菌zot基因的同源物。与前列腺炎病例相关的一些UPEC菌株在低严格性下获得的微弱信号促使我们使用从含有经典NTP结合基序的假定NTPase Zot组蛋白的保守区设计的引物来检测UPEC菌株。这导致在UPEC菌株中发现了一段DNA片段，该片段与从聚合酶链式反应设计的探针杂交。对该DNA片段的进一步分析发现了一个开放阅读框架，命名为泌尿系致病特异性蛋白(USP)。编码USP的基因全长1038bp，编码346个氨基酸，具有合适的SD序列。USP的上游和下游分析显示了原核共识启动子的基序和三个小的ORF，其中SDS和核糖体结合位点与USP的转录方向相同。这些基因位于细菌染色体的特定区域，类似于与UPEC优先相关的基因块，再加上与Tn3转座子家族匹配的基序的存在，使我们相信这可能是一个迄今未知的致病岛。

This study was initiated to search for a homologue of the Vibrio cholerae zot gene in uropathogenic Escherichia coli (UPEC) using a specific DNA probe. The faint signal obtained at low stringency with some UPEC strains associated with prostatitis cases prompted us to examine UPEC strains by PCR using primers designed from the conserved regions of the proteins of the Zot group of putative NTPases containing the classical NTP binding motif. This led to the discovery of a DNA fragment in UPEC strains which hybridized with a probe designed from the PCR. Further analysis of this DNA fragment revealed an ORF which was designated as uropathogenic specific protein (Usp). The gene encoding Usp was 1038 bp long and codes for 346 amino acids with an appropriate SD sequence. Upstream and downstream analysis of usp revealed motifs of prokaryotic consensus promoters and three small ORFs with SDs and ribosome binding sites transcribed in the same direction of usp. The proximity of these set of genes in a specific area of the bacterial chromosome resembling a block of genes preferentially associated with UPEC coupled with the presence of a motif matching that of a Tn3 transposon family lead us to believe that this could be an hitherto unknown pathogenicity island.