Functional Characterization of a Lipoprotein-Encoding Operon in Campylobacter jejuni

• Published in: PloS one Vol. 6; no. 5; p. e20084
• Main Authors: Oakland, Mayumi, Jeon, Byeonghwa, Sahin, Orhan, Shen, Zhangqi, Zhang, Qijing
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23.05.2011; Public Library of Science (PLoS)
• Subjects: Amino acids; Analysis; Antibodies; Bacteria; Base Sequence; Biology; Blood lipids; Campylobacter; Campylobacter coli; Campylobacter jejuni; Campylobacter jejuni - genetics; Cell cycle; Chickens; Cloning; Colonization; Deactivation; Deoxyribonucleic acid; Diarrhea; DNA; DNA microarrays; DNA Primers; E coli; Efflux; Electrophoretic mobility; Escherichia coli; Foodborne pathogens; Gastroenteritis; Gene expression; Gene regulation; Genes; Genome, Bacterial; Genomes; Guillain-Barre syndrome; Haemophilus; Immunoblotting; Immunogenicity; Inactivation; Infections; Intestine; Kinases; Lipoproteins; Lipoproteins - genetics; Motility; Operon; Pathogenesis; Pathogens; Physiological aspects; Poultry; Preventive medicine; Proteins; Signal transduction; Transcription; Transcription (Genetics); Vectors (Biology); United States > US; Iowa City Iowa
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0020084

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. 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. 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.