2CLA

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

Summary for 2CLA

• Entry DOI: 10.2210/pdb2cla/pdb
• Descriptor: CHLORAMPHENICOL ACETYLTRANSFERASE, COBALT (II) ION (3 entities in total)
• Functional Keywords: transferase (acyltransferase)
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 25138.37

Authors

Gibbs, M.R.,Moody, P.C.E.,Leslie, A.G.W. (deposition date: 1990-04-05, release date: 1990-07-15, Last modification date: 2024-02-14)

Primary citation

Gibbs, M.R.,Moody, P.C.,Leslie, A.G.
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.
Biochemistry, 29:11261-11265, 1990

PubMed Abstract: 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.

PubMed: 2271709
DOI: 10.1021/bi00503a015

Experimental method

X-RAY DIFFRACTION (2.35 Å)