title: Mutation in an Unannotated Protein Confers Carbapenem Resistance in Mycobacterium tuberculosis.
abstract: β-Lactams are the most widely used antibacterials. Among β-lactams, carbapenems are considered the last line of defense against recalcitrant infections. As recent developments have prompted consideration of carbapenems for treatment of drug-resistant tuberculosis, it is only a matter of time beforeMycobacterium tuberculosisstrains resistant to these drugs will emerge. In the present study, we investigated the genetic basis that confers such resistance. To our surprise, instead of mutations in the known β-lactam targets, a single nucleotide polymorphism in theRv2421c-Rv2422intergenic region was common amongM. tuberculosismutants selected with meropenem or biapenem. We present data supporting the hypothesis that this locus harbors a previously unidentified gene that encodes a protein. This protein binds to β-lactams, slowly hydrolyzes the chromogenic β-lactam nitrocefin, and is inhibited by select penicillins and carbapenems and the β-lactamase inhibitor clavulanate. The mutation results in a W62R substitution that reduces the protein's nitrocefin-hydrolyzing activity and binding affinities for carbapenems.
authors.affiliation: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.|Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.|Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Kaushik
authors.affiliation: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.|Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Drew T
authors.initials: DT
authors.lastname: Bell
authors.affiliation: Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Varsha
authors.initials: V
authors.lastname: Chauhan
authors.affiliation: Argonne National Laboratory, Argonne, Illinois, USA.|University of Chicago, Chicago, Illinois, USA.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Xia
authors.affiliation: Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.|Argonne National Laboratory, Argonne, Illinois, USA.|University of Chicago, Chicago, Illinois, USA.
authors.forename: Rick L
authors.initials: RL
authors.lastname: Stevens
authors.affiliation: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA lamichhane@jhu.edu.|Taskforce To Study Resistance Emergence & Antimicrobial Development Technology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Gyanu
authors.identifier: 0000-0002-2214-0114
authors.initials: G
authors.lastname: Lamichhane
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology; D019818:Clavulanic Acid / Q000378:metabolism / Q000494:pharmacology; D021901:DNA, Intergenic; D015870:Gene Expression; D056426:Genetic Loci; D006801:Humans; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D016366:Open Reading Frames; D011485:Protein Binding; D013845:Thienamycins / Q000494:pharmacology; D018088:Tuberculosis, Multidrug-Resistant / Q000382:microbiology; D018440:beta-Lactam Resistance / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D021901:DNA, Intergenic; D013845:Thienamycins; D019818:Clavulanic Acid; C021720:nitrocefin; D000077731:Meropenem; C065257:biapenem
keywords: Mycobacterium tuberculosis; antibiotic resistance; carbapenems