Gonococcal Clinical Strains Bearing a Common gdhR Single Nucleotide Polymorphism That Results in Enhanced Expression of the Virulence Gene lctP Frequently Possess a mtrR Promoter Mutation That Decreases Antibiotic Susceptibility

• Type of Material: Article
• Authors: Julio C Ayala, Emory University; Matthew W Schmerer, Centers for Disease Control and Prevention; Ellen N Kersh, Centers for Disease Control and Prevention; Magnus Unemo, Örebro University; William Shafer, Emory University
• Language: English
• Date: 2022-04-26
• Publisher: AMER SOC MICROBIOLOGY
• Publication Version: Final Published Version
• Copyright Statement: This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.
• Final Published Version (URL): http://dx.doi.org/10.1128/mbio.00276-22
• Title of Journal or Parent Work: MBIO
• Volume: 13
• Issue: 2
• Start Page: e0027622
• End Page: e0027622
• Grant/Funding Information: This work was supported by NIH grant AI021150-36 (W.M.S.) and funds from an Intergovernmental Personnel Act from the CDC to J.C.A. and W.M.S. W.M.S. is the recipient of a Senior Research Career Scientist Award from the Biomedical Laboratory Research and Development Service of the U.S. Department of Veterans Affairs. CDC-based coauthors were funded by the CDC. Their work was made possible in part through support from CDC’s Advanced Molecular Detection (AMD-18) and Combating Antibiotic Resistant Bacteria (CARB) programs.
• Keywords: ANTIMICROBIAL RESISTANCE; Science & Technology; Life Sciences & Biomedicine; antibiotic resistance; Neisseria gonorrhoeae; mtrR; INFECTION; lctP; REGULATORS; Microbiology; EVOLUTION; GENOMIC ANALYSIS; gdhR; NEISSERIA-GONORRHOEAE; FADR

Abstract

GdhR is a transcriptional repressor of the virulence factor gene lctP, which encodes a unique L-lactate permease that has been linked to pathogenesis of Neisseria gonorrhoeae, and loss of gdhR can confer increased fitness of gonococci in a female mouse model of lower genital tract infection. In this work, we identified a single nucleotide polymorphism (SNP) in gdhR, which is often present in both recent and historical gonococcal clinical strains and results in a proline (P)-to-serine (S) change at amino acid position 6 (P6S) of GdhR. This mutation (gdhR6) was found to reduce GdhR transcriptional repression at lctP in gonococcal strains containing the mutant protein compared to wild-type GdhR. By using purified recombinant proteins and in vitro DNA-binding and cross-linking experiments, we found that gdhR6 impairs the DNA-binding activity of GdhR at lctP without an apparent effect on protein oligomerization. By analyzing a panel of U.S. (from 2017 to 2018) and Danish (1928 to 2013) clinical isolates, we observed a statistical association between gdhR6 and the previously described adenine deletion in the promoter of mtrR (mtrR-P A-del), encoding the repressor (MtrR) of the mtrCDE operon that encodes the MtrCDE multidrug efflux pump that can export antibiotics, host antimicrobials, and biocides. The frequent association of gdhR6 with the mtrR promoter mutation in these clinical isolates suggests that it has persisted in this genetic background to enhance lctP expression, thereby promoting virulence.