Schwan William R, Ding Hua
University of Wisconsin-La Crosse, La Crosse, WI, USA.
J Pathog. 2017;2017:8694356. doi: 10.1155/2017/8694356. Epub 2017 Dec 27.
Uropathogenic (UPEC) adhere to cells in the human urinary tract via type 1 pili that undergo phase variation where a 314-bp DNA element flips between Phase-ON and Phase-OFF orientations through two site-specific recombinases, FimB and FimE. Three operon transcriptional fusions were created and moved into the clinical UPEC isolate NU149 to determine their temporal regulation in UPEC growing in the urinary tract. Within murine urinary tracts, the UPEC strains demonstrated elevated transcription of and early in the infection, but lower transcription by the fifth day in murine kidneys. In contrast, transcription was much lower than either or early, increased markedly at 24 h after inoculation, and then dropped five days after inoculation. Positioning of was primarily in the Phase-ON position over the time span in UPEC infected bladders, whereas in UPEC infected murine kidneys the Phase-OFF orientation was favored by the fifth day after inoculation. Hemagglutination titers with guinea pig erythrocytes remained constant in UPEC growing in infected murine bladders but fell substantially in UPEC infected kidneys over time. Our results show temporal regulation of gene expression in different environmental niches when UPEC infects the murine urinary tract.
尿路致病性大肠杆菌（UPEC）通过1型菌毛粘附于人类尿道中的细胞，1型菌毛会发生相变，一个314碱基对的DNA元件通过两种位点特异性重组酶FimB和FimE在开启相和关闭相之间翻转。构建了三个操纵子转录融合体，并将其导入临床UPEC分离株NU149，以确定它们在尿道中生长的UPEC中的时间调控。在小鼠尿道内，UPEC菌株在感染早期显示出[具体基因1]和[具体基因2]的转录升高，但在小鼠肾脏中到第五天时转录降低。相比之下，[具体基因3]转录在早期远低于[具体基因1]或[具体基因2]，在接种后24小时显著增加，然后在接种五天后下降。在感染UPEC的膀胱中，[具体基因4]在整个时间段内主要处于开启相位置，而在感染UPEC的小鼠肾脏中，接种后第五天关闭相方向占优势。感染小鼠膀胱中生长的UPEC与豚鼠红细胞的血凝滴度保持恒定，但随着时间推移，感染UPEC的肾脏中的血凝滴度大幅下降。我们的结果表明，当UPEC感染小鼠尿道时，不同环境龛中[相关基因]基因表达存在时间调控。
