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The response of M.HpaII to heteroduplexes.

Authors
  • Laayoun, A
  • Baker, D J
  • Riley, J
  • Smith, S S
Type
Published Article
Journal
Gene
Publisher
Elsevier
Publication Date
Dec 02, 1994
Volume
150
Issue
1
Pages
195–196
Identifiers
PMID: 7959052
Source
Medline
License
Unknown

Abstract

Synthetic oligodeoxyribonucleotide duplexes have been used to study the methylation specificity of M.HpaII, a bacterial DNA methyltransferase. Substrates of four types were compared. A 30-mer containing a Watson-Crick paired CCGG recognition sequence was rapidly methylated at the central cytosine on each strand in the recognition sequence. A 30-mer containing an asymmetrically methylated recognition sequence, of the type transiently produced by DNA replication, was rapidly methylated at the central cytosine on the unmethylated strand. A heteroduplex containing an A.C mispair in the recognition sequence (CCGG/CCAG) was rapidly methylated at the cytosine in the mispair. A heteroduplex containing an A.C and an adjacent C.C mispair in the recognition sequence (CCGG/CCCA) was not methylated at a significant rate. The results show that M.HpaII can tolerate a single mispair at its recognition site in a heteroduplex without loss of activity or specificity.

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