Linked Life Data

10224113

Source:http://linkedlifedata.com/resource/pubmed/id/10224113

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
1999-6-3
pubmed:abstractText
We have identified a new type of S-adenosyl-L-methionine-dependent methyltransferase in the cytosol of Escherichia coli that is expressed in early stationary phase under the control of the RpoS sigma factor. This enzyme catalyzes the monomethyl esterification of trans-aconitate at high affinity (Km = 0.32 mM) and cis-aconitate, isocitrate, and citrate at lower velocities and affinities. We have purified the enzyme to homogeneity by gel-filtration, anion-exchange, and hydrophobic chromatography. The N-terminal amino acid sequence was found to match that expected for the o252 open reading frame at 34.57 min on the E. coli genomic sequence whose deduced amino acid sequence contains the signature sequence motifs of the major class of S-adenosyl-L-methionine-dependent methyltransferases. Overexpression of the o252 gene resulted in an overexpression of the methyltransferase activity, and we have now designated it tam for trans-aconitate methyltransferase. We have generated a knock-out strain of E. coli lacking this activity, and we find that its growth and stationary phase survival are similar to that of the parent strain. We demonstrate the endogenous formation of trans-aconitate methyl ester in extracts of wild type but not tam- mutant cells indicating that trans-aconitate is present in E. coli. Since trans-aconitate does not appear to be a metabolic intermediate in these cells but forms spontaneously from the key citric acid cycle intermediate cis-aconitate, we suggest that its methylation may limit its potential interference in normal metabolic pathways. We have detected trans-aconitate methyltransferase activity in extracts of the yeast Saccharomyces cerevisiae, whereas no activity has been found in extracts of Caenorhabditis elegans or mouse brain.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
274
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13470-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
A novel methyltransferase catalyzes the methyl esterification of trans-aconitate in Escherichia coli.
pubmed:affiliation
Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, California 90095-1569, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.