1t7n
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(New page: 200px<br /><applet load="1t7n" size="450" color="white" frame="true" align="right" spinBox="true" caption="1t7n, resolution 1.90Å" /> '''Crystal structure of...)
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Revision as of 00:55, 21 November 2007
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Crystal structure of the M564G mutant of murine CrAT
Overview
Carnitine acyltransferases catalyze the exchange of acyl groups between, coenzyme A (CoA) and carnitine. They have important roles in many cellular, processes, especially the oxidation of long-chain fatty acids, and are, attractive targets for drug discovery against diabetes and obesity. These, enzymes are classified based on their substrate selectivity for, short-chain, medium-chain, or long-chain fatty acids. Structural, information on carnitine acetyltransferase suggests that residues Met-564, and Phe-565 may be important determinants of substrate selectivity with, the side chain of Met-564 located in the putative binding pocket for acyl, groups. Both residues are replaced by glycine in carnitine, palmitoyltransferases. To assess the functional relevance of this, structural observation, we have replaced these two residues with small, amino acids by mutagenesis, characterized the substrate preference of the, mutants, and determined the crystal structures of two of these mutants., Kinetic studies confirm that the M564G or M564A mutation is sufficient to, increase the activity of the enzyme toward medium-chain substrates with, hexanoyl-CoA being the preferred substrate for the M564G mutant. The, crystal structures of the M564G mutant, both alone and in complex with, carnitine, reveal a deep binding pocket that can accommodate the larger, acyl group. We have determined the crystal structure of the F565A mutant, in a ternary complex with both the carnitine and CoA substrates at a 1.8-A, resolution. The F565A mutation has minor effects on the structure or the, substrate preference of the enzyme.
About this Structure
1T7N is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.
Reference
Structural and biochemical studies of the substrate selectivity of carnitine acetyltransferase., Hsiao YS, Jogl G, Tong L, J Biol Chem. 2004 Jul 23;279(30):31584-9. Epub 2004 May 21. PMID:15155726
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