Campylobacter jejuni CsrA complements an Escherichia coli csrA mutation for the regulation of biofilm formation, motility and cellular morphology but not glycogen accumulation

Abstract

BackgroundAlthough Campylobacter jejuni is consistently ranked as one of the leading causes of bacterial diarrhea worldwide, the mechanisms by which C. jejuni causes disease and how they are regulated have yet to be clearly defined. The global regulator, CsrA, has been well characterized in several bacterial genera and is known to regulate a number of independent pathways via a post transcriptional mechanism, but remains relatively uncharacterized in the genus Campylobacter. Previously, we reported data illustrating the requirement for CsrA in several virulence related phenotypes of C. jejuni strain 81–176, indicating that the Csr pathway is important for Campylobacter pathogenesis.ResultsWe compared the Escherichia coli and C. jejuni orthologs of CsrA and characterized the ability of the C. jejuni CsrA protein to functionally complement an E. coli csrA mutant. Phylogenetic comparison of E. coli CsrA to orthologs from several pathogenic bacteria demonstrated variability in C. jejuni CsrA relative to the known RNA binding domains of E. coli CsrA and in several amino acids reported to be involved in E. coli CsrA-mediated gene regulation. When expressed in an E. coli csrA mutant, C. jejuni CsrA succeeded in recovering defects in motility, biofilm formation, and cellular morphology; however, it failed to return excess glycogen accumulation to wild type levels.ConclusionsThese findings suggest that C. jejuni CsrA is capable of efficiently binding some E. coli CsrA binding sites, but not others, and provide insight into the biochemistry of C. jejuni CsrA.

CsrA Regulates Helicobacter pylori J99 Motility and Adhesion by Controlling Flagella Formation

“…The results were similar to our observations for H. pylori J99. Interestingly, C. jejuni CsrA succeeded in recovering defects in motility, biofilm formation, and cellular morphology of csrA mutant E. coli [45]. However, similar to H. pylori CsrA, the C. jejuni CsrA ortholog was incapable of repressing glycogen accumulation in the csrA mutant E. coli [32,45].…”

A CsrA/RsmA translational regulator gene encoded in the replication region of a Sinorhizobium meliloti cryptic plasmid complements Pseudomonas fluorescens rsmA/E mutants

“…S2). It has been recently reported that the Campylobacter jejuni CsrA protein, expressed from an inducible araBAD promoter, does not repress glycogen production in E. coli (Fields & Thompson, 2012).…”

Feedback control of Campylobacter jejuni flagellin levels through reciprocal binding of FliW to flagellin and the global regulator CsrA

“…This type of regulation optimizes energy expenditure and prevents the accumulation of cytosolic flagellins, which may become toxic to the bacterium. In addition, the FliW regulation of CsrA activity may provide coordinated regulation of flagellin biosynthesis and other CsrA regulated processes such as bacterial adherence, resistance to oxidative stress and virulence, although no target genes have thus far been identified (Fields and Thompson, ; Fields and Thompson, ). Theoretically, mechanisms of regulated binding of CsrA to other transcripts via additional, unidentified CsrA binding proteins may in turn affect flagellin biosynthesis by influencing the level of free CsrA.…”