2cla
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(New page: 200px<br /><applet load="2cla" size="450" color="white" frame="true" align="right" spinBox="true" caption="2cla, resolution 2.35Å" /> '''CRYSTAL STRUCTURE OF...)
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Revision as of 07:02, 21 November 2007
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CRYSTAL STRUCTURE OF THE ASP-199-ASN MUTANT OF CHLORAMPHENICOL ACETYLTRANSFERASE TO 2.35 ANGSTROMS RESOLUTION. STRUCTURAL CONSEQUENCES OF DISRUPTION OF A BURIED SALT-BRIDGE
Overview
The crystal structure of the Asp-199----Asn mutant of chloramphenicol, acetyltransferase (CAT) has been determined to 2.35-A resolution. In, wild-type CAT Asp-199 is involved in a fully buried intrasubunit salt, bridge with Arg-18, an interaction that is adjacent to the active site., Replacement of aspartate with asparagine by site-directed mutagenesis, disrupts this salt bridge and causes extensive conformational changes, within the active site. The imidazole group of the catalytically essential, His-195 is reoriented, with the loss of interactions thought to stabilize, the preferred tautomer of this residue. Arg-18 and Asn-199 form three new, intersubunit interactions as a result of large side-chain torsion angle, changes which cause the movement of two polypeptide loops, some residues, of which are up to 20 A away from the site of the mutation. The new, interactions of Arg-18 and Asn-199 compensate for the loss of the buried, salt bridge and afford near-wild-type thermostability to Asn-199 CAT, albeit with a greatly reduced activity.
About this Structure
2CLA is a Single protein structure of sequence from Escherichia coli with CO as ligand. Active as Chloramphenicol O-acetyltransferase, with EC number 2.3.1.28 Full crystallographic information is available from OCA.
Reference
Crystal structure of the aspartic acid-199----asparagine mutant of chloramphenicol acetyltransferase to 2.35-A resolution: structural consequences of disruption of a buried salt bridge., Gibbs MR, Moody PC, Leslie AG, Biochemistry. 1990 Dec 25;29(51):11261-5. PMID:2271709
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