Assembly of EcoKI DNA methyltransferase requires the C-terminal region of the HsdM modification subunit.
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.
Powell
Lynn M
LM
Institute of Cell and Molecular Biology, The King's Buildings, University of Edinburgh, Edinburgh, Scotland EH9 3JR, UK.
Lejeune
Erwan
E
Hussain
Farhana S
FS
Cronshaw
Andrew D
AD
Kelly
Sharon M
SM
Price
Nicholas C
NC
Dryden
David T F
DT
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
D010446:Peptide Fragments; D021122:Protein Subunits; C093244:DNA modification methylase EcoKI; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)