The Vibrio cholerae chitin utilization program

doi:10.1073/pnas.0308707101

The Vibrio cholerae chitin utilization program

^*Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305; and ^†Department of Biology and McCollum-Pratt Institute, The Johns Hopkins University, Baltimore, MD 21218

Contributed by Saul Roseman, December 29, 2003

Abstract

Chitin, an insoluble polymer of GlcNAc, is an abundant source of carbon, nitrogen, and energy for marine microorganisms. Microarray expression profiling and mutational studies of Vibrio cholerae growing on a natural chitin surface, or with the soluble chitin oligosaccharides (GlcNAc)_2–6, GlcNAc, or the glucosamine dimer (GlcN)₂ identified three sets of differentially regulated genes. We show that (i) ChiS, a sensor histidine kinase, regulates expression of the (GlcNAc)_2–6 gene set, including a (GlcNAc)₂ catabolic operon, two extracellular chitinases, a chitoporin, and a PilA-containing type IV pilus, designated ChiRP (chitin-regulated pilus) that confers a significant growth advantage to V. cholerae on a chitin surface; (ii) GlcNAc causes the coordinate expression of genes involved with chitin chemotaxis and adherence and with the transport and assimilation of GlcNAc; (iii) (GlcN)₂ induces genes required for the transport and catabolism of nonacetylated chitin residues; and (iv) the constitutively expressed MSHA pilus facilitates adhesion to the chitin surface independent of surface chemistry. Collectively, these results provide a global portrait of a complex, multistage V. cholerae program for the efficient utilization of chitin.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: schoolni{at}cmgm.stanford.edu.
Abbreviations: (GlcNAc)_n, chitin oligosaccharides; ChiRP, chitin-regulated pilus; qRT-PCR, quantitative real-time RT-PCR.
↵ § Kirn, T. J., Jude, B. A. & Taylor, R. K. (2003) in American Society for Microbiology, 103rd General Meeting, Washington Convention Center, Washington, DC, p. 115 (abstr.).