Investigating β-Lactam Drug Targets in Mycobacterium tuberculosis Using Chemical Probes

Samantha R. Levine, Kimberly E. Beatty

Research output: Contribution to journalArticlepeer-review

Abstract

Tuberculosis (TB), caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb), infects 10 million people a year. An estimated 25% of humans harbor latent TB infections, an asymptomatic form of the disease. In both active and latent infections, Mtb relies on cell wall peptidoglycan for viability. In the current work, we synthesized fluorescent analogues of β-lactam antibiotics to study two classes of enzymes that maintain Mtb's peptidoglycan: penicillin-binding proteins (PBPs) and l,d-transpeptidases (LDTs). This set of activity-based probes included analogues of three classes of β-lactams: a monobactam (aztreonam-Cy5), a cephalosporin (cephalexin-Cy5), and a carbapenem (meropenem-Cy5). We used these probes to profile enzyme activity in protein gel-resolved lysates of Mtb. All three out-performed the commercial reagent Bocillin-FL, a penam. Meropenem-Cy5 was used to identify β-lactam targets by mass spectrometry, including PBPs, LDTs, and the β-lactamase BlaC. New probes were also used to compare PBP and LDT activity in two metabolic states: dormancy and active replication. We provide the first direct evidence that Mtb dynamically regulates the enzymes responsible for maintaining peptidoglycan in dormancy. Lastly, we profiled drug susceptibility in lysates and found that meropenem inhibits PBPs, LDTs, and BlaC.

Original languageEnglish (US)
Pages (from-to)461-470
Number of pages10
JournalACS Infectious Diseases
Volume7
Issue number2
DOIs
StatePublished - Feb 12 2021
Externally publishedYes

Keywords

  • activity-based probe
  • antibiotic
  • carbapenem
  • fluorescent
  • proteomics
  • tuberculosis

ASJC Scopus subject areas

  • Infectious Diseases

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