Chitinolytic Activity of Listeria monocytogenes EGD Is Regulated by Carbohydrates but Also by the Virulence Regulator PrfA

• Published in: Applied and Environmental Microbiology Vol. 76; no. 19; pp. 6470 - 6476
• Main Authors: Larsen, M.H, Leisner, J.J, Ingmer, H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2010; American Society for Microbiology (ASM)
• Subjects: Acetylglucosamine - metabolism; Animals; Bacteria; Bacterial Adhesion; Bacterial Proteins - physiology; Biological and medical sciences; Blotting, Northern; Carbohydrates; Cell Line; Chitin - metabolism; Chitinases - biosynthesis; Epithelial Cells - microbiology; Food Microbiology; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genes; Humans; Listeria monocytogenes; Listeria monocytogenes - growth & development; Listeria monocytogenes - metabolism; Listeria monocytogenes - pathogenicity; Listeria monocytogenes - physiology; Microbiology; Mutation; Peptide Termination Factors - deficiency; Peptide Termination Factors - physiology; Polymers; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Transcription, Genetic; Virulence; Listeria monocytogenes; Bacteria; Regulation(control); Carbohydrate; Regulator; Virulence
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.00297-10

Chitin, an insoluble polymer of N-acetyl-D-glucosamine (GlcNAc), is one of the most abundant carbohydrate polymers in marine and terrestrial environments. Chitin hydrolysis by Listeria monocytogenes depends on two chitinase-encoding genes, chiA and chiB, and the aim of this study was to investigate their regulation. Chitin induces the expression of both chitinases in late exponential growth phase, and chiA but not chiB is furthermore induced by the monomer GlcNAc. Furthermore, their expression is subjected to catabolite control. Chitinases expressed by bacterial pathogens have proven to be important not only for nutrient acquisition and environmental survival but also for infecting animals and humans. Interestingly, the central L. monocytogenes virulence gene regulator, PrfA, is required for the chitinolytic phenotype, as chitinase activity was significantly reduced in prfA mutant cells compared to its level in wild-type cells. In agreement with this, Northern blot analysis showed that the amounts of chiA and chiB transcripts upon induction by chitin were significantly lower in the prfA mutant than in the wild type. The chitinolytic activity and chiA and chiB expression were reduced in the absence of the sigB gene, indicating that σB is also important for the production of chitinases. The chiA, chiB, and chiA chiB mutants were not impaired for in vitro adhesion and invasion in epithelial cell lines, but the chiA chiB double mutant showed less survival ability in a chitin-enriched medium. The regulation of chitinolytic activity in L. monocytogenes is complex, and taken together, the results indicate that the biological role of this activity may not be limited to the external environment.