A pair of single-strand and double-strand DNA cytosine-N4 methyltransferases from Bacillus centrosporus.
Sequence analysis of the BcnI restriction-modification system revealed the presence of an open reading frame encoding a second cytosine-N4 methyltransferase, M.BcnIA, in the vicinity of the genes specifying the previously characterized cytosine-N4 methyltransferase M.BcnIB and restriction endonuclease R.BcnI. Both methyltransferases were purified from the E. coli cells expressing the individual genes, and their enzymatic efficiencies in vitro were compared with a variety of DNA substrates. Both enzymes act on 5'-CC(C/G)GG-3' sites in double-stranded DNA, however, M.BcnIA can also, with a comparable efficiency, modify the specific targets in single-stranded DNA. The biological significance of the presence of the tandem methyltransferases in the BcnI system is discussed.
Merkiene
E
E
Institute of Biotechnology, Vilnius, Lithuania.
Vilkaitis
G
G
Klimasauskas
S
S
D001407:Bacillus / Q000201:enzymology*; D017104:Bacteriophage M13 / Q000235:genetics; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism; D015257:DNA-Cytosine Methylases / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D013379:Substrate Specificity
D004277:DNA, Single-Stranded; D004279:DNA, Viral; D009838:Oligodeoxyribonucleotides; C039051:DNA modification methylase BcnI; D015257:DNA-Cytosine Methylases