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Structural insights into the enhanced carbapenemase efficiency of OXA-655 compared to OXA-10.

ABSTRACT: Carbapenemases are the main cause of carbapenem resistance in Gram-negative bacteria. How ?-lactamases with weak carbapenemase activity, such as the OXA-10-type class D ?-lactamases, contribute to anti-bacterial drug resistance is unclear. OXA-655 is a T26M and V117L OXA-10 variant, recently identified from hospital wastewater. Despite exhibiting stronger carbapenemase activity towards ertapenem (ETP) and meropenem (MEM) in Escherichia coli, OXA-655 exhibits reduced activity towards oxyimino-substituted ?-lactams like ceftazidime. Here, we have solved crystal structures of OXA-10 in complex with imipenem (IPM) and ETP, and OXA-655 in complex with MEM in order to unravel the structure-function relationship and the impact of residue 117 in enzyme catalysis. The new crystal structures show that L117 is situated at a critical position with enhanced Van der Waals interactions to L155 in the omega loop. This restricts the movements of L155 and could explain the reduced ability for OXA-655 to bind a bulky oxyimino group. The V117L replacement in OXA-655 makes the active site S67 and the carboxylated K70 more water exposed. This could affect the supply of new deacylation water molecules required for hydrolysis and possibly the carboxylation rate of K70. But most importantly, L117 leaves more space for binding of the hydroxyethyl group in carbapenems. In summary, the crystal structures highlight the importance of residue 117 in OXA-10 variants for carbapenemase activity. This study also illustrates the impact of a single amino acid substitution on the substrate profile of OXA-10 and the evolutionary potential of new OXA-10 variants.

SUBMITTER: Leiros HS

PROVIDER: S-EPMC7459404 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Structural insights into the enhanced carbapenemase efficiency of OXA-655 compared to OXA-10.

Leiros Hanna-Kirsti S HS Thomassen Ane Molden AM Samuelsen Ørjan Ø Flach Carl-Fredrik CF Kotsakis Stathis D SD Larsson D G Joakim DGJ

FEBS open bio 20200808 9

Carbapenemases are the main cause of carbapenem resistance in Gram-negative bacteria. How β-lactamases with weak carbapenemase activity, such as the OXA-10-type class D β-lactamases, contribute to anti-bacterial drug resistance is unclear. OXA-655 is a T26M and V117L OXA-10 variant, recently identified from hospital wastewater. Despite exhibiting stronger carbapenemase activity towards ertapenem (ETP) and meropenem (MEM) in Escherichia coli, OXA-655 exhibits reduced activity towards oxyimino-sub ...[more]

PMID: 32683794

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Project description:Purpose:A novel variant of OXA-23, named OXA-423, was identified in an Acinetobacter baumannii clinical isolate. The aim of this study was to analyse the resistance phenotype of OXA-423. Methods:The A. baumannii strain WY-0713 was isolated from an intensive care unit patient. PCR was used to detect the bla OXA-23-like genes. Amplifying, cloning and sequencing were performed for the complete bla OXA-23-like. The novel bla OXA-423 and its ancestor bla OXA-23 were cloned into the expression vector pET-28b(+), and transformed into E. coli Rosetta (DE3) for antibiotic susceptibility testing. SDS-PAGE, modified Hodge test and CarbaNP test were used for detecting the expression of OXA-423 and OXA-23. Results:PCR screening of A. baumannii WY-0713 was positive for bla OXA-23-like genes. Sequencing of the PCR product identi?ed a novel bla OXA-23-like, named bla OXA-423 which encoding OXA-423. OXA-423 differed from OXA-23 by a crucial amino acid substitution (Val128Ala). The V128A substitution was located at the conserved active-site motifs SAV of OXA-23. Antibiotic susceptibility testing performed using isogenic E. coli showed that the MICs of E. coli Rosetta (pET-OXA-423) for penicillins and carbapenems were lower (reduced MICs 4-fold to 16-fold) than that of E. coli Rosetta (pET-OXA-23). The MICs of cefotaxime, ceftazidime and aztreonam for both transformants remained the same as the acceptor strain. Moreover, OXA-423 was slightly inhibited by sulbactam, clavulanic acid and tazobactam. SDS-PAGE analysis showed that OXA-423 and OXA-23 were conspicuously expressed. Modified Hodge test and CarbaNP test were positive demonstrated both of them were functional. Conclusion:OXA-423, the first report of an amino acid substitution located at conserved active-site motifs of OXA-23, conferred lower MIC values of penicillins and carbapenems as compared with OXA-23, while without affecting the resistance pro?les of expanded-spectrum cephalosporins and aztreonam.

Dataset Information

Structural insights into the enhanced carbapenemase efficiency of OXA-655 compared to OXA-10.

Publications

Structural insights into the enhanced carbapenemase efficiency of OXA-655 compared to OXA-10.

Similar Datasets

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