Download MendeleyStructures of the Class D Carbapenemase OXA-24 from Acinetobacter baumannii in Complex with Doripenem.
Schneider, K.D., Ortega, C.J., Renck, N.A., Bonomo, R.A., Powers, R.A., Leonard, D.A.(2011) J Mol Biol 406: 583-594
- PubMed: 21215758
- DOI: https://doi.org/10.1016/j.jmb.2010.12.042
- Primary Citation of Related Structures:
3PAE, 3PAG - PubMed Abstract:
The emergence of class D β-lactamases with carbapenemase activity presents an enormous challenge to health practitioners, particularly with regard to the treatment of infections caused by Gram-negative pathogens such as Acinetobacter baumannii. Unfortunately, class D β-lactamases with carbapenemase activity are resistant to β-lactamase inhibitors. To better understand the details of the how these enzymes bind and hydrolyze carbapenems, we have determined the structures of two deacylation-deficient variants (K84D and V130D) of the class D carbapenemase OXA-24 with doripenem bound as a covalent acyl-enzyme intermediate. Doripenem adopts essentially the same configuration in both OXA-24 variant structures, but varies significantly when compared to the non-carbapenemase class D member OXA-1/doripenem complex. The alcohol of the 6α hydroxyethyl moiety is directed away from the general base carboxy-K84, with implications for activation of the deacylating water. The tunnel formed by the Y112/M223 bridge in the apo form of OXA-24 is largely unchanged by the binding of doripenem. The presence of this bridge, however, causes the distal pyrrolidine/sulfonamide group to bind in a drastically different conformation compared to doripenem bound to OXA-1. The resulting difference in the position of the side-chain bridge sulfur of doripenem is consistent with the hypothesis that the tautomeric state of the pyrroline ring contributes to the different carbapenem hydrolysis rates of OXA-1 and OXA-24. These findings represent a snapshot of a key step in the catalytic mechanism of an important class D enzyme, and might be useful for the design of novel inhibitors.
Organizational Affiliation:
Department of Chemistry, Grand Valley State University, Allendale, MI 49401, USA.
