Identification of an isoschizomer of the HhaI DNA methyltransferase in Mycoplasma arthritidis

摘要: The genome of Mycoplasma arthritidis strain 158 has modified cytosine residues at AGCT sequences that render the DNA resistant to digestion with AluI restriction endonuclease. methyltransferase responsible for base modification previously been designated MarI. From complete sequence M. arthritidis, we identify Marth_orf138 as a candidate marI gene. was cloned in Escherichia coli and its TGA codons converted TGG. isolated from E. cells expressing gene degraded by nuclease, indicating does not code However, found have acquired resistance endonuclease HhaI. Genomic also be HhaI (recognizes GCGC). isoschizomer methyltransferase, coded Marth_orf138, is MarII. Transformation significantly affected plasmid sites, mycoplasma lacks recognizes GCGC sites.