Source:http://linkedlifedata.com/resource/pubmed/id/17685588
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
35
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| pubmed:dateCreated |
2007-8-28
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| pubmed:abstractText |
Penicillin-binding proteins (PBPs) and beta-lactamases are members of large families of bacterial enzymes. These enzymes undergo acylation at a serine residue with their respective substrates as the first step in their catalytic events. Penicillin-binding protein 5 (PBP 5) of Escherichia coli is known to perform a dd-carboxypeptidase reaction on the bacterial peptidoglycan, the major constituent of the cell wall. The roles of the active site residues Lys47 and Lys213 in the catalytic machinery of PBP 5 have been explored. By a sequence of site-directed mutagenesis and chemical modification, we individually introduced gamma-thialysine at each of these positions. The pH dependence of kcat/Km and of kcat for the wild-type PBP 5 and for the two gamma-thialysine mutant variants at positions 47 and 213 were evaluated. The pH optimum for the enzyme was at 9.5-10.5. The ascending limb to the pH optimum is due to Lys47; hence, this residue exists in the free-base form for catalysis. The descending limb from the pH optimum is contributed to by both Lys213 and a water molecule coordinated to Lys47. These results have been interpreted as Lys47 playing a key role in proton-transfer events in the course of catalysis during both the acylation and deacylation events. However, the findings for Lys213 argue for a protonated state at the pH optimum. Lys213 serves as an electrostatic anchor for the substrate.
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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/Cysteine,
http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Lysine,
http://linkedlifedata.com/resource/pubmed/chemical/Penicillin-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Peptidoglycan,
http://linkedlifedata.com/resource/pubmed/chemical/Proton Pumps,
http://linkedlifedata.com/resource/pubmed/chemical/S-2-aminoethyl cysteine,
http://linkedlifedata.com/resource/pubmed/chemical/beta-Lactamases
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| pubmed:status |
MEDLINE
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| pubmed:month |
Sep
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| pubmed:issn |
0006-2960
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
4
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| pubmed:volume |
46
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| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
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| pubmed:pagination |
10113-21
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| pubmed:meshHeading |
pubmed-meshheading:17685588-Acylation,
pubmed-meshheading:17685588-Amino Acid Substitution,
pubmed-meshheading:17685588-Binding Sites,
pubmed-meshheading:17685588-Catalysis,
pubmed-meshheading:17685588-Cell Wall,
pubmed-meshheading:17685588-Cysteine,
pubmed-meshheading:17685588-Escherichia coli,
pubmed-meshheading:17685588-Escherichia coli Proteins,
pubmed-meshheading:17685588-Hydrogen-Ion Concentration,
pubmed-meshheading:17685588-Lysine,
pubmed-meshheading:17685588-Models, Chemical,
pubmed-meshheading:17685588-Models, Molecular,
pubmed-meshheading:17685588-Mutagenesis, Site-Directed,
pubmed-meshheading:17685588-Penicillin-Binding Proteins,
pubmed-meshheading:17685588-Peptidoglycan,
pubmed-meshheading:17685588-Protein Binding,
pubmed-meshheading:17685588-Proton Pumps,
pubmed-meshheading:17685588-beta-Lactamases
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| pubmed:year |
2007
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| pubmed:articleTitle |
Catalytic mechanism of penicillin-binding protein 5 of Escherichia coli.
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| pubmed:affiliation |
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, N.I.H., Extramural
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