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rdf:type |
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lifeskim:mentions |
umls-concept:C0006968,
umls-concept:C0014314,
umls-concept:C0220781,
umls-concept:C0598002,
umls-concept:C0678594,
umls-concept:C0680022,
umls-concept:C1450791,
umls-concept:C1710548,
umls-concept:C1722730,
umls-concept:C1883220,
umls-concept:C2603343
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pubmed:issue |
41
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pubmed:dateCreated |
2005-10-10
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pubmed:databankReference |
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pubmed:abstractText |
The first step in the biosynthesis of the medicinally important carbapenem family of beta-lactam antibiotics is catalyzed by carboxymethylproline synthase (CarB), a unique member of the crotonase superfamily. CarB catalyzes formation of (2S,5S)-carboxymethylproline [(2S,5S)-t-CMP] from malonyl-CoA and l-glutamate semialdehyde. In addition to using a cosubstrate, CarB catalyzes C-C and C-N bond formation processes as well as an acyl-coenzyme A hydrolysis reaction. We describe the crystal structure of CarB in the presence and absence of acetyl-CoA at 2.24 A and 3.15 A resolution, respectively. The structures reveal that CarB contains a conserved oxy-anion hole probably required for decarboxylation of malonyl-CoA and stabilization of the resultant enolate. Comparison of the structures reveals that conformational changes (involving His(229)) in the cavity predicted to bind l-glutamate semialdehyde occur on (co)substrate binding. Mechanisms for the formation of the carboxymethylproline ring are discussed in the light of the structures and the accompanying studies using isotopically labeled substrates; cyclization via 1,4-addition is consistent with the observed labeling results (providing that hydrogen exchange at the C-6 position of carboxymethylproline does not occur). The side chain of Glu(131) appears to be positioned to be involved in hydrolysis of the carboxymethylproline-CoA ester intermediate. Labeling experiments ruled out the possibility that hydrolysis proceeds via an anhydride in which water attacks a carbonyl derived from Glu(131), as proposed for 3-hydroxyisobutyryl-CoA hydrolase. The structural work will aid in mutagenesis studies directed at altering the selectivity of CarB to provide intermediates for the production of clinically useful carbapenems.
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pubmed:grant |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/3-hydroxyisobutyryl-CoA hydrolase,
http://linkedlifedata.com/resource/pubmed/chemical/Aldehydes,
http://linkedlifedata.com/resource/pubmed/chemical/Anhydrides,
http://linkedlifedata.com/resource/pubmed/chemical/Carbapenems,
http://linkedlifedata.com/resource/pubmed/chemical/Carbon-Carbon Lyases,
http://linkedlifedata.com/resource/pubmed/chemical/Enoyl-CoA Hydratase,
http://linkedlifedata.com/resource/pubmed/chemical/Esters,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamates,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Histidine,
http://linkedlifedata.com/resource/pubmed/chemical/Proline,
http://linkedlifedata.com/resource/pubmed/chemical/Selenomethionine,
http://linkedlifedata.com/resource/pubmed/chemical/Thiolester Hydrolases,
http://linkedlifedata.com/resource/pubmed/chemical/Trypsin,
http://linkedlifedata.com/resource/pubmed/chemical/carboxymethylproline synthase,
http://linkedlifedata.com/resource/pubmed/chemical/glutamate-1-semialdehyde
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pubmed:status |
MEDLINE
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pubmed:month |
Oct
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
14
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pubmed:volume |
280
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
34956-65
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pubmed:dateRevised |
2007-8-13
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pubmed:meshHeading |
pubmed-meshheading:16096274-Aldehydes,
pubmed-meshheading:16096274-Anhydrides,
pubmed-meshheading:16096274-Binding Sites,
pubmed-meshheading:16096274-Carbapenems,
pubmed-meshheading:16096274-Carbon-Carbon Lyases,
pubmed-meshheading:16096274-Catalysis,
pubmed-meshheading:16096274-Chromatography, Liquid,
pubmed-meshheading:16096274-Crystallography, X-Ray,
pubmed-meshheading:16096274-Enoyl-CoA Hydratase,
pubmed-meshheading:16096274-Escherichia coli,
pubmed-meshheading:16096274-Esters,
pubmed-meshheading:16096274-Glutamates,
pubmed-meshheading:16096274-Glutamic Acid,
pubmed-meshheading:16096274-Histidine,
pubmed-meshheading:16096274-Hydrogen Bonding,
pubmed-meshheading:16096274-Mass Spectrometry,
pubmed-meshheading:16096274-Models, Chemical,
pubmed-meshheading:16096274-Models, Molecular,
pubmed-meshheading:16096274-Mutagenesis,
pubmed-meshheading:16096274-Proline,
pubmed-meshheading:16096274-Protein Binding,
pubmed-meshheading:16096274-Protein Conformation,
pubmed-meshheading:16096274-Protein Structure, Secondary,
pubmed-meshheading:16096274-Selenomethionine,
pubmed-meshheading:16096274-Substrate Specificity,
pubmed-meshheading:16096274-Thiolester Hydrolases,
pubmed-meshheading:16096274-Trypsin
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pubmed:year |
2005
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pubmed:articleTitle |
Structural and mechanistic studies on carboxymethylproline synthase (CarB), a unique member of the crotonase superfamily catalyzing the first step in carbapenem biosynthesis.
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pubmed:affiliation |
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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