1ei5: Difference between revisions

[[Image:1ei5.jpg|left|200px]]<br /><applet load="1ei5" size="350" color="white" frame="true" align="right" spinBox="true"  

BACKGROUND: beta-Lactam compounds are the most widely used antibiotics. They inactivate bacterial DD-transpeptidases, also called penicillin-binding proteins (PBPs), involved in cell-wall biosynthesis. The most common bacterial resistance mechanism against beta-lactam compounds is the synthesis of beta-lactamases that hydrolyse beta-lactam rings. These enzymes are believed to have evolved from cell-wall DD-peptidases. Understanding the biochemical and mechanistic features of the beta-lactam targets is crucial because of the increasing number of resistant bacteria. DAP is a D-aminopeptidase produced by Ochrobactrum anthropi. It is inhibited by various beta-lactam compounds and shares approximately 25% sequence identity with the R61 DD-carboxypeptidase and the class C beta-lactamases. RESULTS: The crystal structure of DAP has been determined to 1.9 A resolution using the multiple isomorphous replacement (MIR) method. The enzyme folds into three domains, A, B and C. Domain A, which contains conserved catalytic residues, has the classical fold of serine beta-lactamases, whereas domains B and C are both antiparallel eight-stranded beta barrels. A loop of domain C protrudes into the substrate-binding site of the enzyme. CONCLUSIONS: Comparison of the biochemical properties and the structure of DAP with PBPs and serine beta-lactamases shows that although the catalytic site of the enzyme is very similar to that of beta-lactamases, its substrate and inhibitor specificity rests on residues of domain C. DAP is a new member of the family of penicillin-recognizing proteins (PRPs) and, at the present time, its enzymatic specificity is clearly unique.

1EI5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Ochrobactrum_anthropi Ochrobactrum anthropi]. Active as [http://en.wikipedia.org/wiki/D-stereospecific_aminopeptidase D-stereospecific aminopeptidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.11.19 3.4.11.19] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EI5 OCA].  

[[Category: Beeumen, J Van.]]

[[Category: Frere, J M.]]

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