Assembly of EcoKI DNA methyltransferase requires the C-terminal region of the HsdM modification subunit

L M Powell, E Lejeune, F S Hussain, A D Cronshaw, S M Kelly, N C Price, D T F Dryden

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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 EcoKl 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 EcoKl is essential for the assembly of the EcoKI methyltransferase. (C) 2002 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)129-137
Number of pages9
JournalBiophysical Chemistry
Issue number2
Publication statusPublished - 21 Jan 2003

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