Source:http://linkedlifedata.com/resource/pubmed/id/10878136
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rdf:type | |
lifeskim:mentions | |
pubmed:dateCreated |
2000-8-30
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pubmed:abstractText |
Vancomycin resistance in Enterococcus gallinarum results from the production of UDP-MurNAc-pentapeptide[D-Ser]. VanT, a membrane-bound serine racemase, is one of three proteins essential for this resistance. To investigate the selectivity of racemization of L-Ser or L-Ala by VanT, a strain of Escherichia coli TKL-10 that requires D-Ala for growth at 42 degrees C was used as host for transformation experiments using plasmids containing the full-length vanT from Ent. gallinarum or the alanine racemase gene (alr) of Bacillus stearothermophilus: both plasmids were able to complement E. coli TKL-10 at 42 degrees C. No alanine or serine racemase activities were detected in the host strain E. coli TKL-10 grown at 30, 34 or 37 degrees C. Serine and alanine racemase activities were found almost exclusively (96%) in the membrane fraction of E. coli TKL-10/pCA4(vanT): the alanine racemase activity of VanT was 14% of the serine racemase activity in both E. coli TKL-10/pCA4(vanT) and E. coli XL-1 Blue/pCA4(vanT). Alanine racemase activity was present mainly (95%) in the cytoplasmic fraction of E. coli TKL-10/pJW40(alr), with a trace (1.6%) of serine racemase activity. Additionally, DNA encoding the soluble domain of VanT was cloned and expressed in E. coli M15 as a His-tagged polypeptide and purified: this polypeptide also exhibited both serine and alanine racemase activities; the latter was approximately 18% of the serine racemase activity, similar to that of the full-length, membrane-bound enzyme. N-terminal sequencing of the purified His-tagged polypeptide revealed a single amino acid sequence, indicating that the formation of heterodimers between subunits of His-tagged C-VanT and endogenous alanine racemases from E. coli was unlikely. The authors conclude that the membrane-bound serine racemase VanT also has alanine racemase activity but is able to racemize serine more efficiently than alanine, and that the cytoplasmic domain is responsible for the racemase activity.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Alanine Racemase,
http://linkedlifedata.com/resource/pubmed/chemical/Anti-Bacterial Agents,
http://linkedlifedata.com/resource/pubmed/chemical/Bacterial Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Membrane Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Racemases and Epimerases,
http://linkedlifedata.com/resource/pubmed/chemical/Vancomycin,
http://linkedlifedata.com/resource/pubmed/chemical/serine racemase
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pubmed:status |
MEDLINE
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pubmed:month |
Jul
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pubmed:issn |
1350-0872
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
146 ( Pt 7)
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
1727-34
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:10878136-Alanine Racemase,
pubmed-meshheading:10878136-Amino Acid Sequence,
pubmed-meshheading:10878136-Anti-Bacterial Agents,
pubmed-meshheading:10878136-Bacillus,
pubmed-meshheading:10878136-Bacterial Proteins,
pubmed-meshheading:10878136-Blotting, Western,
pubmed-meshheading:10878136-Enterococcus,
pubmed-meshheading:10878136-Escherichia coli,
pubmed-meshheading:10878136-Membrane Proteins,
pubmed-meshheading:10878136-Molecular Sequence Data,
pubmed-meshheading:10878136-Plasmids,
pubmed-meshheading:10878136-Racemases and Epimerases,
pubmed-meshheading:10878136-Sequence Alignment,
pubmed-meshheading:10878136-Temperature,
pubmed-meshheading:10878136-Transformation, Bacterial,
pubmed-meshheading:10878136-Vancomycin,
pubmed-meshheading:10878136-Vancomycin Resistance
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pubmed:year |
2000
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pubmed:articleTitle |
Serine and alanine racemase activities of VanT: a protein necessary for vancomycin resistance in Enterococcus gallinarum BM4174.
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pubmed:affiliation |
Department of Biochemistry, University of Cambridge, Tennis Court Road, The Downing Site, Cambridge CB2 1QW, UK. caa22@cable.net.co
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, Non-U.S. Gov't
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