Mechanism-Based Inactivation of Mycobacterium tuberculosis Isocitrate Lyase 1 by (2 R,3 S)-2-Hydroxy-3-(nitromethyl)succinic acid

J Am Chem Soc. 2021 Oct 27;143(42):17666-17676. doi: 10.1021/jacs.1c07970. Epub 2021 Oct 19.

Abstract

The isocitrate lyase paralogs of Mycobacterium tuberculosis (ICL1 and 2) are essential for mycobacterial persistence and constitute targets for the development of antituberculosis agents. We report that (2R,3S)-2-hydroxy-3-(nitromethyl)succinic acid (5-NIC) undergoes apparent retro-aldol cleavage as catalyzed by ICL1 to produce glyoxylate and 3-nitropropionic acid (3-NP), the latter of which is a covalent-inactivating agent of ICL1. Kinetic analysis of this reaction identified that 5-NIC serves as a robust and efficient mechanism-based inactivator of ICL1 (kinact/KI = (1.3 ± 0.1) × 103 M-1 s-1) with a partition ratio <1. Using enzyme kinetics, mass spectrometry, and X-ray crystallography, we identified that the reaction of the 5-NIC-derived 3-NP with the Cys191 thiolate of ICL1 results in formation of an ICL1-thiohydroxamate adduct as predicted. One aspect of the design of 5-NIC was to lower its overall charge compared to isocitrate to assist with cell permeability. Accordingly, the absence of the third carboxylate group will simplify the synthesis of pro-drug forms of 5-NIC for characterization in cell-infection models of M. tuberculosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / metabolism
  • Glyoxylates / chemistry
  • Glyoxylates / metabolism
  • Isocitrate Lyase / antagonists & inhibitors*
  • Isocitrate Lyase / chemistry
  • Isocitrate Lyase / metabolism
  • Kinetics
  • Models, Chemical
  • Mycobacterium tuberculosis / enzymology*
  • Nitro Compounds / chemistry
  • Nitro Compounds / metabolism
  • Propionates / chemistry
  • Propionates / metabolism
  • Protein Binding
  • Succinates / chemical synthesis
  • Succinates / chemistry*
  • Succinates / metabolism

Substances

  • Enzyme Inhibitors
  • Glyoxylates
  • Nitro Compounds
  • Propionates
  • Succinates
  • Isocitrate Lyase
  • glyoxylic acid
  • 3-nitropropionic acid