title: Molecular cloning and expression in Escherichia coli of two modification methylase genes of Bacillus subtilis.
abstract: Two modification methylase genes of Bacillus subtilis R were cloned in Escherichia coli by using a selection procedure which is based on the expression of these genes. Both genes code for DNA-methyltransferases which render the DNA of the cloning host E. coli HB101 insensitive to the BspRI (5'-GGCC) endonuclease of Bacillus sphaericus R. One of the cloned genes is part of the restriction-modification (RM) system BsuRI of B. subtilis R with specificity for 5'-GGCC. The other one is associated with the lysogenizing phage SP beta B and produces the methylase M.BsuP beta BI with specificity for 5'-GGCC. The fragment carrying the SP beta B-derived gene also directs the synthesis in E. coli of a third methylase activity (M.BsuP beta BII), which protects the host DNA against HpaII and MspI cleavage within the sequence 5'-CCGG. Indirect evidence suggests that the two SP beta B modification activities are encoded by the same gene. No cross-hybridization was detected either between the M.BsuRI and M.BsuP beta B genes or between these and the modification methylase gene of B. sphaericus R, which codes for the enzyme M.BspRI with 5'-GGCC specificity.
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D008780:Methyltransferases / Q000235:genetics*
chemical_list: D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases; D004262:DNA Restriction Enzymes