An orphan DNA (cytosine-5-)-methyltransferase in Vibrio cholerae
IR@IICB: CSIR-Indian Institute of Chemical Biology, KolkataView Archive Info
An orphan DNA (cytosine-5-)-methyltransferase in
Infectious Diseases and Immunology
5-Methyl cytosine (m5C) was detected in genomic DNA of the enteric pathogen Vibrio cholerae
by HPLC analysis and immunoblotting with m5C-specific antibody. Although cleavage with the
restriction endonuclease EcoRII revealed the absence of a Dcm homologue in V. cholerae, analysis
of the genome sequence indicated the presence of a gene, designated in this study as vchM,
which encodes a DNA (cytosine-5-)-methyltransferase (m5C-MTase) designated M.Vch. M.Vch is
not associated with a restriction endonuclease or a mismatch very short patch repair (Vsr)-like
endonuclease and is hence an ‘orphan’ or solitary MTase, although analysis of a phylogenetic tree
indicated that related cytosine MTases are all components of restriction-modification systems.
M.Vch recognizes and methylates the first 59 C in the degenerate sequence 59-RCCGGY-39.
RT-PCR analysis suggested that vchM gene expression is increased during the stationary phase
of growth. During stationary phase, the spontaneous mutation frequency in the V. cholerae
wild-type strain was significantly higher than in the corresponding vchM mutant strain, suggesting
that the presence of M.Vch and the absence of a very short patch (VSP) repair-like system
imposes upon V. cholerae a mutator phenotype.
Banerjee, Sanjib and Chowdhury, Rukhsana (2006) An orphan DNA (cytosine-5-)-methyltransferase in Vibrio cholerae. Microbiology SGM, 152. pp. 1055-1062.