The effect of methylation on DNA replication in Salmonella enterica serovar typhimurium.
The DNA adenine methylase of Salmonella typhimurium methylates adenine at GATC sequences. Strains deficient in this methylase are not well transformed by methylated plasmids, but unmethylated plasmids transform them at high frequencies. Hemimethylated daughter molecules accumulate after the transformation of dam(-) strains with fully methylated plasmids, suggesting that hemimethylation prevents DNA replication. It will also be shown that plasmids isolated from dam(-) bacteria are hemimethylated by restriction enzyme digestion. These results may explain why newly formed daughter molecules are not substrates for immediate reinitiation of DNA replication in dam(-) bacteria.
Aloui
Amine
A
Laboratoire de biochimie et biologie moléculaire, Unité de biochimie des lipides et interaction des macromolécules en biologie, 03/UR/0902, faculté des sciences de Bizerte, Zarzouna 7021, Tunisia. aminealoui@yahoo.fr
Chatty
Abdelwaheb
A
El May
Alya
A
Landoulsi
Ahmed
A
D019175:DNA Methylation; D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics*; D010957:Plasmids; D012485:Salmonella typhi / Q000235:genetics*; D014169:Transformation, Bacterial
D004269:DNA, Bacterial