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

Authors
Type
Published Article
Journal
Biophysical Chemistry
0301-4622
Publisher
Elsevier
Publication Date
Volume
103
Issue
2
Pages
129–137
Identifiers
PMID: 12568936
Source
Medline
License
Unknown

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.

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