Project description:These experiment were performed to show a serogroup conversion in Vibrio cholerae from O1 to O139. For this purpose, V. cholerae O1 WT = A1552 was grown on crab shell fragments to induce natural competence for transformation. Purified DNA (2 ug each) from strain VCO139-Kan was added after 24h and the cells grwon further for 24h. The VCO139-Kan strain is a MO10 derivative (both O139 serogroup) which harbors a Kanamycin cassette in the O139 region (as part of the operon between wbfA and wbfB w/o own promotor) for better selection. Transformants were selected on LB+Kan plates. Two groups of transformants were gained: Group I had a full exchange of the O1 region by the O139 region (clones serogroup-converted: SGC#1-3); the crossovers for the homologous recombination event had occurred within or upstream of the gmhD gene and in most instances within or downstream of the homolog gene of VC0271. This implies an exchange of an at least 33 kb spanning O1 genomic region by more than 42 kb of the O139 region. Group II had only half of the O139 region transfered and therefore half of the O1 region kept (clones HSGC#4-6). We analyzed their genotype and found that all of them had undergone a homologous recombination event with one crossover in or upstream of the gmhD gene and the second one inside the VC0254 and IS1358 gene. The transformation experiment was done three independent times (I - III). Three clones from group I and group II were selected from each experiment and analyzed by microarray hybridization (BioPrime. Array CGH Genomic Labeling from Invitrogen). Two microarray replicates were done per clone.
Project description: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. This SuperSeries is composed of the SubSeries listed below.