High Frequency, Spontaneous motA Mutations in Campylobacter jejuni Strain 81-176

Krystle L Mohawk,Jason W Sahl,Patricia Guerry,Frédéric Poly,David A Rasko,Qijing Zhang

doi:10.1371/journal.pone.0088043

Krystle L Mohawk, Jason W Sahl + Show 4 more

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https://doi.org/10.1371/journal.pone.0088043

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Abstract

Campylobacter jejuni is an important cause of bacterial diarrhea worldwide. The pathogenesis of C. jejuni is poorly understood and complicated by phase variation of multiple surface structures including lipooligosaccharide, capsule, and flagellum. When C. jejuni strain 81-176 was plated on blood agar for single colonies, the presence of translucent, non-motile colonial variants was noted among the majority of opaque, motile colonies. High-throughput genomic sequencing of two flagellated translucent and two opaque variants as well as the parent strain revealed multiple genetic changes compared to the published genome. However, the only mutated open reading frame common between the two translucent variants and absent from the opaque variants and the parent was motA, encoding a flagellar motor protein. A total of 18 spontaneous motA mutations were found that mapped to four distinct sites in the gene, with only one class of mutation present in a phase variable region. This study exemplifies the mutative/adaptive properties of C. jejuni and demonstrates additional variability in C. jejuni beyond phase variation.

Highlights

Campylobacter is one of the most common sources of diarrheal disease in developing as well as developed countries [1]
Strain 81-176/55 was isolated as single, encapsulated colony from the current Good Manufacturing Practices (cGMP)-stock of 81-176 that was sequenced by The Institute for Genomic Research (TIGR) [24]
Given that colonial variation in C. coli has been linked with motility [26], variant colonies were tested in soft agar (Figure 1C)

Summary

Introduction

Campylobacter is one of the most common sources of diarrheal disease in developing as well as developed countries [1]. Infection with Campylobacter, or campylobacteriosis, is a self-limiting disease associated with a variety of symptoms that range from watery diarrhea to dysentery accompanied with fever. The first published C. jejuni genome sequence, that of strain NCTC11168, revealed reversible phase variation in genes encoding surface antigens mediated by slip strand mismatch (SSM) repair at homopolymeric tracts of 8 or more Gs or Cs [11]. Many of these GC tracts are located in genes involved in the biosynthesis of surface structures including the polysaccharide capsule and lipooligosaccharide (LOS), both of which have been demonstrated to be phase variable [12]. SSM errors are attributed to the absence of a functional methyldirected DNA mismatch repair system (MMR) in C. jejuni [11]

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