C6 Hydroxymethyl-Substituted Carbapenem MA-1-206 Inhibits the Major Acinetobacter baumannii Carbapenemase OXA-23 by Impeding Deacylation

Journal Article · Thu Apr 14 00:00:00 EDT 2022 · mBio (Online)

DOI:https://doi.org/10.1128/mbio.00367-22· OSTI ID:1903998

Stewart, Nichole K. ^[1]; Toth, Marta ^[1]; Alqurafi, Maha A. ^[2]; Chai, Weirui ^[2]; Nguyen, Thu Q. ^[2]; Quan, Pojun ^[2]; Lee, Mijoon ^[1]; Buynak, John D. ^[2]; Smith, Clyde A. ^[3]; Vakulenko, Sergei B.  ^[1]

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1. University of Notre Dame, IN (United States)
2. Southern Methodist University, Dallas, TX (United States)
3. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL); Stanford University, CA (United States)

Acinetobacter baumannii has become a major nosocomial pathogen, as it is often multidrug-resistant, which results in infections characterized by high mortality rates. The bacterium achieves high levels of resistance to β-lactam antibiotics by producing β-lactamases, enzymes which destroy these valuable agents. Historically, the carbapenem family of b-lactam antibiotics have been the drugs of choice for treating A. baumannii infections. However, their effectiveness has been significantly diminished due to the pathogen’s production of carbapenem-hydrolyzing class D β-lactamases (CHDLs); thus, new antibiotics and inhibitors of these enzymes are urgently needed. Here, we describe a new carbapenem antibiotic, MA-1-206, in which the canonical C6 hydroxyethyl group has been replaced with hydroxymethyl. The antimicrobial susceptibility studies presented here demonstrated that this compound is more potent than meropenem and imipenem against A. baumannii producing OXA-23, the most prevalent CHDL of this pathogen, and also against strains producing the CHDL OXA-24/40 and the class B metallo-β-lactamase VIM-2. Our kinetic and mass spectrometry studies revealed that this drug is a reversible inhibitor of OXA-23, where inhibition takes place through a branched pathway. X-ray crystallographic studies, molecular docking, and molecular dynamics simulations of the OXA-23-MA-1-206 complex show that the C6 hydroxymethyl group forms a hydrogen bond with the carboxylated catalytic lysine of OXA-23, effectively preventing deacylation. These results provide a promising strategy for designing a new generation of CHDL-resistant carbapenems to restore their efficacy against deadly A. baumannii infections. Carbapenem antibiotics are the drugs of choice for treatment of deadly infections caused by Gram-negative bacteria. However, their efficacy is severely compromised by the wide spread of carbapenem-hydrolyzing class D β-lactamases (CHDLs). The importance of this research is the discovery that substitution of the canonical hydroxyethyl group of carbapenems by a hydroxymethyl significantly enhances stability against inactivation by the major CHDL of Acinetobacter baumannii, OXA-23. These results provide a novel strategy for designing next-generation, carbapenemase-stable carbapenems to fight multidrug-resistant infections caused by Gram-negative pathogens

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL); University of Notre Dame, IN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER); National Institutes of Health (NIH)
• Grant/Contract Number: 1R01AI155723; 1R15AI142699; P41 RR001209
• OSTI ID: 1903998
• Journal Information: mBio (Online), Vol. 13, Issue 3; ISSN 2150-7511
• Publisher: American Society for Microbiology (ASM)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
beta-lactamase
OXA-23
Acinetobacter
inhibitor
carbapenem
crystal structure
catalytic mechanism
antibiotic resistance