Linked Life Data

10551869

Source:http://linkedlifedata.com/resource/pubmed/id/10551869

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
46
pubmed:dateCreated
2000-1-3
pubmed:abstractText
Initial velocity determinations were conducted with human DNA (cytosine-5) methyltransferase (DNMT1) on unmethylated and hemimethylated DNA templates in order to assess the mechanism of the reaction. Initial velocity data with DNA and S-adenosylmethionine (AdoMet) as variable substrates and product inhibition studies with methylated DNA and S-adenosylhomocysteine (AdoHcy) were obtained and evaluated as double-reciprocal plots. These relationships were linear for plasmid DNA, exon-1 from the imprinted small nuclear ribonucleoprotein-associated polypeptide N, (CGG.CCG)(12), (m(5)CGG. CCG)(12), and (CGG.CCG)(73) but were not linear for (CGG. Cm(5)CG)(12). Inhibition by AdoHcy was apparently competitive versus AdoMet and uncompetitive/noncompetitive versus DNA at </=20 microM AdoMet. Addition of the product (methylated DNA) to unmethylated plasmid DNA increased V(max(app)) resulting in mixed stimulation and inhibition. Velocity equations indicated a two-step mechanism as follows: first, activation of DNMT1 by methylated DNA that bound to an allosteric site, and second, the addition of AdoMet and DNA to the catalytic site. The preference of DNMT1 for hemimethylated DNA may be the result of positive cooperativity of AdoMet binding mediated by allosteric activation by the methylated CG steps. We propose that this activation plays a role in vivo in the regulation of maintenance methylation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
274
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
33011-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Recombinant human DNA (cytosine-5) methyltransferase. II. Steady-state kinetics reveal allosteric activation by methylated dna.
pubmed:affiliation
Center for Genome Research, Institute of Biosciences and Technology, Texas A & M University, Texas Medical Center, Houston, Texas 77030-3303, USA. abacolla@ibt.tamu.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't