Structural and functional characterization of fosfomycin resistance conferred by FosB from Enterococcus faecium. (22nd December 2021)

• Record Type: Journal Article
• Authors: Wiltsie, Vanessa; Travis, Skye; Shay, Madeline R.; Simmons, Zachary; Frantom, Patrick; Thompson, Matthew K.
• Is Part Of: Protein science. Volume 31:Number 3(2022)
• Page Start: 580
• Page End: 590
• Publication Date: 2021-12-22
• Subjects: antimicrobial resistance -- Bacillithiol -- crystallography -- Enterococcus faecium -- ESKAPE pathogens -- Fosfomycin -- Thiol transferase; Proteins -- Periodicals; 572.6
• DOI: 10.1002/pro.4253
• Languages: English
• ISSNs: 0961-8368

Abstract

Abstract: The Gram‐positive pathogen Enterococcus faecium is one of the leading causes of hospital‐acquired vancomycin resistant enterococci (VRE) infections. E. faecium has extensive multidrug resistance and accounts for more than two million infections in the United States each year. FosB is a fosfomycin resistance enzyme found in Gram‐positive pathogens like E. faecium . Typically, the FosB enzymes are Mn 2+ ‐dependent bacillithiol (BSH) transferases that inactivate fosfomycin through nucleophilic addition of the thiol to the antibiotic. However, our kinetic analysis of FosB Ef shows that the enzyme does not utilize BSH as a thiol substrate, unlike the other well characterized FosB enzymes. Here we report that FosB Ef is a Mn 2+ ‐dependent L ‐cys transferase. In addition, we have determined the three‐dimensional X‐ray crystal structure of FosB Ef in complex with fosfomycin at a resolution of 2.0 Å. A sequence similarity network (SSN) was generated for the FosB family to investigate the unexpected substrate selectivity. Three non‐conserved residues were identified in the SSN that may contribute to the substrate selectivity differences in the family of enzymes. Our structural and functional characterization of FosB Ef establishes the enzyme as a potential target and may prove useful for future structure‐based development of FosB inhibitors to increase the efficacy of fosfomycin. Abstract : PDB Code(s): 7n7g ;