Premium
Roles of DNA adenine methylation in controlling replication of the REPI replicon of plasmid pColV‐K30
Author(s) -
Gammie A. E.,
Crosa J. H.
Publication year - 1991
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1991.tb02133.x
Subject(s) - replicon , biology , origin of replication , dna replication , plasmid , origin recognition complex , dna , methylation , genetics , seqa protein domain , eukaryotic dna replication , microbiology and biotechnology
Summary DNA adenine methylation controls DNA replication of plasmids containing the prototypic REPI replicon by affecting protein recognition and by altering the helical stability of the origin. Denaturing gradient gel electrophoresis shows that adenine methylated origin DNA is more easily melted than unmethylated. However, because an added DNA adenine methylation ( dam ) site at the origin, whether in or out of phase with other helically aligned dam sites, actually prevents replication, we conclude that destabilization of the helix is not the exclusive function of adenine methyfation in REPI replication. We find that the conformation and degree of methylation at the origin, features which are important for protein recognition, are essential for replication. In fact, RepI, a protein required for replication initiation at REPI replicons, contains a region homologous with a domain in proteins which specifically recognize and bind 5′‐GATC‐3′. We propose that the dam sites in the origin play a dual role: one is destabilization of the helix, and the other is protein recognition.