title: Assembly of EcoKI DNA methyltransferase requires the C-terminal region of the HsdM modification subunit.
abstract: The methyltransferase component of type I DNA restriction and modification systems comprises three subunits, one DNA sequence specificity subunit and two DNA modification subunits. Limited proteolysis of the EcoKI methyltransferase shows that a 55-kDa N-terminal fragment of the 59-kDa modification subunit is resistant to degradation. We have purified this fragment and determined by mass spectrometry that proteolysis removes 43 or 44 amino acids from the C-terminus. The fragment fails to interact with the other subunits even though it still possesses secondary and tertiary structure and the ability to bind the S-adenosylmethionine cofactor. We conclude that the C-terminal region of the modification subunit of EcoKI is essential for the assembly of the EcoKI methyltransferase.
authors.affiliation: Institute of Cell and Molecular Biology, The King's Buildings, University of Edinburgh, Edinburgh, Scotland EH9 3JR, UK.
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Powell
authors.forename: Erwan
authors.initials: E
authors.lastname: Lejeune
authors.forename: Farhana S
authors.initials: FS
authors.lastname: Hussain
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Cronshaw
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Kelly
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Price
authors.forename: David T F
authors.initials: DT
authors.lastname: Dryden
mesh_terms: D000595:Amino Acid Sequence; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010449:Peptide Mapping; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; C093244:DNA modification methylase EcoKI; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)