Transcriptomic analysis reveals the role of RcsB in suppressing bacterial chemotaxis, flagellar assembly and infection i

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ORIGINAL ARTICLE

Transcriptomic analysis reveals the role of RcsB in suppressing bacterial chemotaxis, flagellar assembly and infection in Yersinia enterocolitica Jiao Meng1 · Jiaqi Bai1 · Jingyu Chen1  Received: 18 January 2020 / Revised: 1 May 2020 / Accepted: 1 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Defining the Rcs (Regulator of Capsule Synthesis) regulon in Enterobacteriaceae has been the major focus of several recent studies. The overall role of the Rcs system in Yersinia enterocolitica is largely unknown. Our previous study showed that RcsB inhibits motility, biofilm formation and c-di-GMP production by negatively regulating flhDC, hmsHFRS and hmsT expression. To identify other cellular functions regulated by the RcsB, gene expression profiles of the wild type and ΔrcsB mutant were compared by RNA-Seq in this study. A total of 132 differentially expressed genes regulated by the RcsB have been identified, of which 114 were upregulated and 18 were downregulated. Further, the results of RNA sequencing were discussed with a focus on the predictive roles of RcsB in the inhibition of bacterial chemotaxis, flagellar assembly and infection. To confirm these predictions, we experimentally verified that the ΔrcsB mutant activated chemotactic behavior and flagella biosynthesis, and exhibited enhanced adhesion and invasion of Y. enterocolitica to Caco-2 cells. Although RcsB largely inhibits these physiological activities, the presence of RcsB is still of great significance for optimizing the survival of Y. enterocolitica as evidenced by our previous report that RcsB confers some level of resistance to the cationic antimicrobial peptide polymyxin B in Y. enterocolitica. Overall, the information provided in this study complements our understanding of Rcs phosphorelay in the regulation of Y. enterocolitica pathogenicity, and, simultaneously, provides clues to additional roles of the Rcs system in other members of family Enterobacteriaceae. Keywords  Yersinia enterocolitica · RcsB · Chemotaxis · Flagella biosynthesis · Infection

Introduction Yersinia enterocolitica is a psychotropic zoonotic pathogen that causes yersiniosis which, in humans, causes acute gastroenteritis and, occasionally, more serious conditions such as pseudoappendicitis and even sepsis (Bari et al. 2011; Fabrega and Vila 2012). Y. enterocolitica is listed in the annual Communicated by M. Kupiec. Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s0029​4-020-01083​-x) contains supplementary material, which is available to authorized users. * Jingyu Chen [email protected] 1



Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, 17 Qinghua East Rd., P.O. Box 398, Beijing 100083, China

reports of the European Food Safety Authority (EFSA) as the third most common enteropathogen, after Campylobacter and Salmonella (Zadernowska et al. 2014). In some countries, it is on a par with Salmonella as a