title: Single-stranded DNA binding and methylation by EcoP1I DNA methyltransferase.
abstract: EcoP1I methyltransferase (M.EcoP1I) belongs to the type III restriction-modification system encoded by prophage P1 that infects Escherichia coli. Binding of M.EcoP1I to double-stranded DNA and single-stranded DNA has been characterized. Binding to both single- and double-stranded DNA could be competed out by unlabeled single-stranded DNA. Metal ions did not influence DNA binding. Interestingly, M.EcoP1I was able to methylate single-stranded DNA. Kinetic parameters were determined for single- and double-stranded DNA methylation. This feature of the enzyme probably functions in protecting the phage genome from restriction by type III restriction enzymes and thus could be considered as an anti-restriction system. This study describing in vitro methylation of single-stranded DNA by the type III methyltransferase EcoP1I allows understanding of the mechanism of action of these enzymes and also their role in the biology of single-stranded phages.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Srivani
authors.initials: S
authors.lastname: Sistla
authors.forename: Vinita
authors.initials: V
authors.lastname: Krishnamurthy
authors.forename: Desirazu N
authors.initials: DN
authors.lastname: Rao
mesh_terms: D019175:DNA Methylation; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry; D004789:Enzyme Activation; D004795:Enzyme Stability; D011485:Protein Binding; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000737:chemistry*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C483474:DNA methyltransferase EcoP1I; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)