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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
34
|
| pubmed:dateCreated |
1995-10-6
|
| pubmed:abstractText |
Salmonella typhimurium orotate phosphoribosyltransferase (OPRTase) catalyzes the formation of orotidine 5'-monophosphate (OMP) from orotate and alpha-D-5-phosphoribosyl-1-pyrophosphate (PRPP). There are five highly conserved lysine residues (Lys-19, -26, -73, -100, and -103) in S. typhimurium OPRTase. Here, we report the results of mutagenesis and substrate analog studies to investigate the functional roles of these lysines. Together with information from X-ray crystallography [Scapin, G., Grubmeyer, C., & Sacchettini, J. C. (1994) Biochemistry 33, 1287-1294; Scapin, G., Ozturk, D. H., Grubmeyer, C., & Sacchettini, J. C. (1995) Biochemistry 34, 10744-10754], sequence comparisons, and chemical modification [Grubmeyer, C., Segura, E., & Dorfman, R. (1993) J. Biol. Chem. 268, 20299-20304], this work permits the assignment of functions of the five conserved lysines. Lys-19 is external to the active site, and its mutation to glutamine had little effect on enzyme activity. Lys-26 forms a hydrogen bond to OMP at the 3'-hydroxyl group, and its mutation produced 3-10-fold decreases in kcat. Lys-73 extends into the active site, and a conformational change allows it to interact with either the 5'-phosphate of OMP or the 2-hydroxyl and alpha-phosphoryl oxygen of PRPP in their respective substrate complexes. Mutation of Lys-73 produced a 50-100-fold decrease in kcat and an 8-12-fold increase in the KM value for PRPP. Mutation of Lys-100 produced a 5-fold decrease in kcat and a 3-fold increase in the KM for PRPP, consistent with its location within the active site, near the pyrophosphate moiety of PRPP.(ABSTRACT TRUNCATED AT 250 WORDS)
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| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Diphosphates,
http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Inhibitors,
http://linkedlifedata.com/resource/pubmed/chemical/Lysine,
http://linkedlifedata.com/resource/pubmed/chemical/Orotate Phosphoribosyltransferase,
http://linkedlifedata.com/resource/pubmed/chemical/Phosphoribosyl Pyrophosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Uridine Monophosphate,
http://linkedlifedata.com/resource/pubmed/chemical/orotidylic acid
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Aug
|
| pubmed:issn |
0006-2960
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
29
|
| pubmed:volume |
34
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
10755-63
|
| pubmed:dateRevised |
2007-11-14
|
| pubmed:meshHeading |
pubmed-meshheading:7545005-Base Sequence,
pubmed-meshheading:7545005-Binding Sites,
pubmed-meshheading:7545005-Computer Graphics,
pubmed-meshheading:7545005-Diphosphates,
pubmed-meshheading:7545005-Enzyme Inhibitors,
pubmed-meshheading:7545005-Enzyme Stability,
pubmed-meshheading:7545005-Kinetics,
pubmed-meshheading:7545005-Lysine,
pubmed-meshheading:7545005-Molecular Sequence Data,
pubmed-meshheading:7545005-Molecular Structure,
pubmed-meshheading:7545005-Mutagenesis, Site-Directed,
pubmed-meshheading:7545005-Orotate Phosphoribosyltransferase,
pubmed-meshheading:7545005-Phosphoribosyl Pyrophosphate,
pubmed-meshheading:7545005-Protein Binding,
pubmed-meshheading:7545005-Protein Structure, Tertiary,
pubmed-meshheading:7545005-Salmonella typhimurium,
pubmed-meshheading:7545005-Substrate Specificity,
pubmed-meshheading:7545005-Uridine Monophosphate
|
| pubmed:year |
1995
|
| pubmed:articleTitle |
Locations and functional roles of conserved lysine residues in Salmonella typhimurium orotate phosphoribosyltransferase.
|
| pubmed:affiliation |
Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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