Deoxyribonucleic Acid Adenine and Cytosine Methylation in Salmonella typhimurium and Salmonella typhi

Abstract

The methylations of adenine in the sequence —GATC— and of the second cytosine in the sequence — [Formula: see text] — were studied in Salmonella typhimurium and in Salmonella typhi . The study was carried out by using endonucleases which restrict the plasmid pBR322 by cleavage at the sequences —GATC— ( Dpn I and Mbo I) and — [Formula: see text] — ( Eco RII). The restriction patterns obtained for this plasmid isolated from transformed S. typhimurium and S. typhi were compared with those of pBR322 isolated from Escherichia coli K-12. In E. coli K-12, adenines at the sequence —GATC— and the second cytosines at — [Formula: see text] — are met hylated by enzymes coded for by the genes dam and dem , respectively. From comparison of the restriction patterns obtained, it is concluded that S. typhimurium and S. typhi contain genes responsible for deoxyribonucleic acid methylation equivalent to E. coli K-12 genes dam and dcm .