Download MendeleyStructural and Dynamic Features of Acinetobacter baumannii OXA-66 beta-Lactamase Explain Its Stability and Evolution of Novel Variants.
Klamer, Z.L., June, C.M., Wawrzak, Z., Taracila, M.A., Grey, J.A., Benn, A.M.I., Russell, C.P., Bonomo, R.A., Powers, R.A., Leonard, D.A., Szarecka, A.(2024) J Mol Biol 436: 168603-168603
- PubMed: 38729259
- DOI: https://doi.org/10.1016/j.jmb.2024.168603
- Primary Citation of Related Structures:
8SQ7, 8SQ8 - PubMed Abstract:
OXA-66 is a member of the OXA-51 subfamily of class D β-lactamases native to the Acinetobacter genus that includes Acinetobacter baumannii, one of the ESKAPE pathogens and a major cause of drug-resistant nosocomial infections. Although both wild type OXA-66 and OXA-51 have low catalytic activity, they are ubiquitous in the Acinetobacter genomes. OXA-51 is also remarkably thermostable. In addition, newly emerging, single and double amino acid variants show increased activity against carbapenems, indicating that the OXA-51 subfamily is growing and gaining clinical significance. In this study, we used molecular dynamics simulations, X-ray crystallography, and thermal denaturation data to examine and compare the dynamics of OXA-66 wt and its gain-of-function variants: I129L (OXA-83), L167V (OXA-82), P130Q (OXA-109), P130A, and W222L (OXA-234). Our data indicate that OXA-66 wt also has a high melting temperature, and its remarkable stability is due to an extensive and rigid hydrophobic bridge formed by a number of residues around the active site and harbored by the three loops, P, Ω, and β5-β6. Compared to the WT enzyme, the mutants exhibit higher flexibility only in the loop regions, and are more stable than other robust carbapenemases, such as OXA-23 and OXA-24/40. All the mutants show increased rotational flexibility of residues I129 and W222, which allows carbapenems to bind. Overall, our data support the hypothesis that structural features in OXA-51 and OXA-66 promote evolution of multiple highly stable variants with increased clinical relevance in A. baumannii.
Organizational Affiliation:
Department of Cell and Molecular Biology, Grand Valley State University, Allendale, MI, USA.
