Wiebe Helene, Gürlebeck Doreen, Groß Jana, Dreck Katrin, Pannen Derk, Ewers Christa, Wieler Lothar H, Schnetz Karin
Institute for Genetics, University of Cologne, Cologne, Germany.
Center for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany.
J Bacteriol. 2015 Aug;197(16):2713-20. doi: 10.1128/JB.00263-15. Epub 2015 Jun 15.
The presumptive transcriptional regulator YjjQ has been identified as being virulence associated in avian pathogenic Escherichia coli (APEC). In this work, we characterize YjjQ as transcriptional repressor of the flhDC operon, encoding the master regulator of flagellar synthesis, and of additional loci. The latter include gfc (capsule 4 synthesis), ompC (outer membrane porin C), yfiRNB (regulated c-di-GMP synthesis), and loci of poorly defined function (ybhL and ymiA-yciX). We identify the YjjQ DNA-binding sites at the flhDC and gfc promoters and characterize a DNA-binding sequence motif present at all promoters found to be repressed by YjjQ. At the flhDC promoter, the YjjQ DNA-binding site overlaps the RcsA-RcsB DNA-binding site. RcsA-RcsB likewise represses the flhDC promoter, but the repression by YjjQ and that by RcsA-RcsB are independent of each other. These data suggest that YjjQ is an additional regulator involved in the complex control of flhDC at the level of transcription initiation. Furthermore, we show that YjjQ represses motility of the E. coli K-12 laboratory strain and of uropathogenic E. coli (UPEC) strains CFT073 and 536. Regulation of flhDC, yfiRNB, and additional loci by YjjQ may be features relevant for pathogenicity.
Escherichia coli is a commensal and pathogenic bacterium causing intra- and extraintestinal infections in humans and farm animals. The pathogenicity of E. coli strains is determined by their particular genome content, which includes essential and associated virulence factors that control the cellular physiology in the host environment. However, the gene pools of commensal and pathogenic E. coli are not clearly differentiated, and the function of virulence-associated loci needs to be characterized. In this study, we characterize the function of yjjQ, encoding a transcription regulator that was identified as being virulence associated in avian pathogenic E. coli (APEC). We characterize YjjQ as transcriptional repressor of flagellar motility and of additional loci related to pathogenicity.
推测的转录调节因子YjjQ已被确定与禽致病性大肠杆菌（APEC）的毒力相关。在本研究中，我们将YjjQ鉴定为flhDC操纵子的转录阻遏物，该操纵子编码鞭毛合成的主要调节因子以及其他基因座。后者包括gfc（荚膜4合成）、ompC（外膜孔蛋白C）、yfiRNB（受调控的环二鸟苷酸合成）以及功能定义不明确的基因座（ybhL和ymiA - yciX）。我们确定了flhDC和gfc启动子处的YjjQ DNA结合位点，并鉴定了在所有被YjjQ抑制的启动子中存在的DNA结合序列基序。在flhDC启动子处，YjjQ DNA结合位点与RcsA - RcsB DNA结合位点重叠。RcsA - RcsB同样抑制flhDC启动子，但YjjQ的抑制作用与RcsA - RcsB的抑制作用相互独立。这些数据表明，YjjQ是在转录起始水平参与flhDC复杂调控的另一种调节因子。此外，我们表明YjjQ抑制大肠杆菌K - 12实验室菌株以及尿路致病性大肠杆菌（UPEC）菌株CFT073和536的运动性。YjjQ对flhDC、yfiRNB和其他基因座的调控可能是与致病性相关的特征。
大肠杆菌是一种共生菌和病原菌，可引起人类和农场动物的肠内和肠外感染。大肠杆菌菌株的致病性由其特定的基因组内容决定，其中包括控制宿主环境中细胞生理学的必需和相关毒力因子。然而，共生和致病性大肠杆菌的基因库并未明确区分，毒力相关基因座的功能需要进行表征。在本研究中，我们表征了yjjQ的功能，yjjQ编码一种转录调节因子，该调节因子已被确定与禽致病性大肠杆菌（APEC）的毒力相关。我们将YjjQ鉴定为鞭毛运动性和其他与致病性相关基因座的转录阻遏物。
