title: Functional characterization of VC1929 of Vibrio cholerae El Tor: role in mannose-sensitive haemagglutination, virulence and utilization of sialic acid.
abstract: The nonadhesive mutant CD11 of Vibrio cholerae El Tor, defective in expression of mannose-sensitive haemagglutinin, lacks a protein when compared with its parent strain. Determination of the amino acid sequence revealed the identity of the protein as the product of VC1929, which is annotated to encode a protein, DctP, involved in the transport of C₄-dicarboxylates. We cloned the dctP gene in pUC19 vector and expressed it in mutant CD11. Expression of DctP in the resulting complemented strain restored virulence, adhesive and colonizing capabilities, mannose-sensitive haemagglutination (MSHA) and ability to grow in medium containing sialic acid as a sole carbon source. The mutation in CD11 was caused by insertion of an adenine nucleotide in the reading frame of dctP. Recombinant purified DctP protein showed MSHA of human red blood cells, and protected rabbits against infection by V. cholerae. The protein was localized in membrane and cell wall fractions. The mutant, recombinant CD11 expressing DctP and parent strains were grown in M9 minimal medium in the presence of various carbohydrates (glucose, malate, fumarate, succinate or N-acetylneuraminic acid). The mutant was unable to grow in minimal medium containing N-acetylneuraminic acid (sialic acid) as the sole carbon source whereas the recombinant and parent strains utilized all the sugars tested. It is concluded that DctP is a mannose-sensitive haemagglutinin and a virulence factor and is involved in the utilization of sialic acid.
authors.affiliation: Microbiology Division, Central Drug Research Institute, CSIR, Lucknow 226001, India.
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Sharma
authors.affiliation: Microbiology Division, Central Drug Research Institute, CSIR, Lucknow 226001, India.
authors.forename: The Su
authors.initials: TS
authors.lastname: Moe
authors.affiliation: Microbiology Division, Central Drug Research Institute, CSIR, Lucknow 226001, India.
authors.forename: Ranjana
authors.initials: R
authors.lastname: Srivastava
authors.affiliation: Department of Biochemistry, University of Lucknow, Lucknow 226001, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Chandra
authors.affiliation: Microbiology Division, Central Drug Research Institute, CSIR, Lucknow 226001, India.
authors.forename: Brahm S
authors.initials: BS
authors.lastname: Srivastava
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D029382:Dicarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D006384:Hemagglutination; D006386:Hemagglutination Tests; D006388:Hemagglutinins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008358:Mannose / Q000378:metabolism*; D051379:Mice; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D011817:Rabbits; D014734:Vibrio cholerae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029382:Dicarboxylic Acid Transporters; D006388:Hemagglutinins; D037521:Virulence Factors; D019158:N-Acetylneuraminic Acid; D008358:Mannose