Genetic organization of pre-CTX and CTX prophages in the genome of an environmental Vibrio cholerae non-O1, non-O139 strain

Maiti, Diganta and Das, Bhabatosh and Saha, Arjun and Nandy, Ranjan K and Nair, G. Balakrish and Bhadra, Rupak K (2006) Genetic organization of pre-CTX and CTX prophages in the genome of an environmental Vibrio cholerae non-O1, non-O139 strain. MICROBIOLOGY-SGM, 152. pp. 3633-3641.

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    Abstract

    The cholera toxin (CT) is a critical determinant of the virulence of epidemic Vibrio cholerae strains.The ctxAB operon encoding CT is part of the genome of a filamentous bacteriophage CTXW, which may integrate as a single copy or as multiple copies in the genome of V. cholerae. The CTXW genome is composed of RS2 (2?4 kb) and core (4?5 kb) regions. In the present study extensive genetic mapping analyses indicated that two copies of tandemly arrayed CTX prophages are integrated in the small chromosome of an environmental V. cholerae strain, VCE232, belonging to serogroup O4. Further mapping revealed that the integration of prophages has occurred in the same genetic locus of the small chromosome of VCE232 as that of V. cholerae O1 biotype El Tor strains. Interestingly, a new type of RS2-like element 3?5 kb in size was found in the CTX prophage genome in the small chromosome of VCE232. Cloning followed by sequencing of the new RS2-like element of VCE232 revealed the presence of three ORFs, which probably encode highly divergent types of phage regulatory proteins. Furthermore, the strain VCE232 also harbours two copies of a tandemly arranged CTX prophage devoid of the ctxAB genes, called pre-CTX prophage, in its large chromosome. The presence of multiple copies of diverse CTX prophages in both the chromosomes of VCE232 suggests that toxigenic environmental V. cholera non-O1, non-O139 strains could play a role in the emergence of new epidemic clones.

    Item Type: Article
    URI: http://www.eprints.iicb.res.in/id/eprint/2440
    Subjects: Infectious Diseases and Immunology
    Divisions: Indian Institute of Chemical Biology
    Depositing User: Ms Sutapa Ganguly
    Date Deposited: 01 Feb 2016 12:08
    Last Modified: 01 Feb 2016 14:55
    Official URL: http://dx.doi.org/10.1099/mic.0.2006/000117-0
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