YjjQ Represses Transcription of flhDC and Additional Loci in Escherichia coli

Abstract

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. IMPORTANCEEscherichia 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.

Hopping into a hot seat: Role of DNA structural features on IS5-mediated gene activation and inactivation under stress

“…IS 5 insertion points occurred within the segmented SIDD sequence with G(x) values ranging from ~1 to ~7 as compared to a baseline value of 12 for the region shown. A number of negative regulatory proteins (RcsAB, YjjQ, OmpR, Fur, IHF, LrhA, MatA, H-NS), positive regulatory proteins (Crp) bind to this region [ 55 – 59 ]. Of note is the RcsAB protein, which, as a part of the RcsC phosphorelay system that responds to a variety of environmental inputs including surface-sensing [ 60 ], could influence DNA structural features relevant to transposon target acquisition.…”

Avian Pathogenic Escherichia coli (APEC): An Overview of Virulence and Pathogenesis Factors, Zoonotic Potential, and Control Strategies

“…Multiple transcriptional regulators have shown a role in APEC pathogenesis [ 14 , 15 , 37 , 93 , 94 , 95 ]. The AutA and AutR, two global transcriptional regulators, mediate the expression of K1 capsule and acid resistance systems, and change in adaptive lifestyle to facilitate infection [ 14 ].…”

“…McbR (MqsR-controlled colonic acid and biofilm regulator) plays a role in biofilm formation and stress response [ 94 ], whereas tyr R (a transcriptional regulator involved in the biosynthesis and transport of aromatic amino acids) promotes invasion, motility, and intracellular survival [ 37 ]. YjjQ (transcriptional regulator, LuxR family) contributes to flagellar motility [ 93 ], and RfaH, a transcriptional anti-terminator, contributes to invasion, intracellular survival, and resistance to serum bactericidal activity [ 95 ].…”

Transcriptional Regulator YqeI, Locating at ETT2 Locus, Affects the Pathogenicity of Avian Pathogenic Escherichia coli

“…The flagellum is a motor organelle and a protein export apparatus, controlling bacterial motility and behavior [ 26 ]. Many factors have been reported to be capable of affecting the flagella assembly, such as the two-component system PhoP/Q [ 27 ], the global transcriptional regulator YjjQ [ 28 ] and the type VI secretion system component IcmF [ 29 ] and ETT2 locus. In UPEC, in the absence of ETT2, the secretion of FliC, FliD, FlgK and FlgM through the flagella T3SS was decreased [ 23 ].…”