Abstract
We report the crystal structure of E. coli ketopantoate hydroxymethyltransferase (KPHMT) at 1.9 A resolution, in complex with its product, ketopantoate. KPHMT catalyzes the first step in the biosynthesis of pantothenate (vitamin B(5)), the precursor of coenzyme A and the acyl carrier protein cofactor. The structure of the decameric enzyme was solved by multiwavelength anomalous dispersion to locate 160 selenomethionine sites and phase 560 kDa of protein, making it the largest structure solved by this approach. KPHMT adopts the (betaalpha)(8) barrel fold and is a member of the phosphoenolpyruvate/pyruvate superfamily. The active site contains a ketopantoate bidentately coordinated to Mg(2+). Similar binding is likely for the substrate, alpha-ketoisovalerate, orienting the C3 for deprotonation.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Crystallography, X-Ray
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Dimerization
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Escherichia coli / enzymology*
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Escherichia coli / genetics
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Gene Expression
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Hydroxymethyl and Formyl Transferases / chemistry*
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Hydroxymethyl and Formyl Transferases / genetics
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Hydroxymethyl and Formyl Transferases / metabolism*
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Magnesium / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Molecular Structure
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Molecular Weight
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Pantothenic Acid / biosynthesis
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Protein Structure, Secondary
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Selenomethionine / chemistry*
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Sequence Homology, Amino Acid
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Spectrum Analysis, Raman
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Static Electricity
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Substrate Specificity
Substances
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Recombinant Proteins
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Pantothenic Acid
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Selenomethionine
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Hydroxymethyl and Formyl Transferases
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3-methyl-2-oxobutanoate hydroxymethyltransferase
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Magnesium