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Functional Characterization of a Lipoprotein-Encoding Operon in Campylobacter jejuni
PLoS ONE
  • Mayumi Oakland, Iowa State University
  • Byeonghwa Jeon, Iowa State University
  • Orhan Sahin, Iowa State University
  • Zhangqi Shen, Iowa State University
  • Qijing Zhang, Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
5-23-2011
DOI
10.1371/journal.pone.0020084
Abstract
Background Bacterial lipoproteins have important functions in bacterial pathogenesis and physiology. In Campylobacter jejuni, a major foodborne pathogen causing gastroenteritis in humans, the majority of lipoproteins have not been functionally characterized. Previously, we showed by DNA microarray that CmeR, a transcriptional regulator repressing the expression of the multidrug efflux pump CmeABC, modulates the expression of a three-gene operon (cj0089, cj0090, and cj0091) encoding a cluster of lipoproteins in C. jejuni. Methodology/Principal Findings In this work, we characterized the function and regulation of the cj0089-cj0090-cj0091 operon. In contrast to the repression of cmeABC, CmeR activates the expression of the lipoprotein genes and the regulation is confirmed by immunoblotting using anti-Cj0089 and anti-Cj0091 antibodies. Gel mobility shift assay showed that CmeR directly binds to the promoter of the lipoprotein operon, but the binding is much weaker compared with the promoter of cmeABC. Analysis of different cellular fractions indicated that Cj0089 was associated with the inner membrane, while Cj0091 was located on the outer membrane. Inactivation of cj0091, but not cj0089, significantly reduced the adherence of C. jejuni to INT 407 cells in vitro, indicating that Cj0091 has a function in adherence. When inoculated into chickens, the Cj0091 mutant also showed a defect in early colonization of the intestinal tract, suggesting that Cj0091 contributes to Campylobacter colonization in vivo. It was also shown that Cj0091 was produced and immunogenic in chickens that were naturally infected by C. jejuni. Conclusion/Significance These results indicate that the lipoprotein operon is subject to direct regulation by CmeR and that Cj0091 functions as an adhesion mechanism in C. jejuni and contributes to Campylobacter colonization of the intestinal tract in animal hosts.
Comments

This article is from PLoS ONE 6(5): e20084. doi:10.1371/journal.pone.0020084. Posted with permission.

Rights
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Copyright Owner
Oakland et al
Language
en
File Format
application/pdf
Citation Information
Mayumi Oakland, Byeonghwa Jeon, Orhan Sahin, Zhangqi Shen, et al.. "Functional Characterization of a Lipoprotein-Encoding Operon in Campylobacter jejuni" PLoS ONE Vol. 6 Iss. 5 (2011) p. e20084
Available at: http://works.bepress.com/qijing-zhang/12/