Structure of Ddn, the Deazaflavin-Dependent Nitroreductase From Mycobacterium Tuberculosis Involved in Bioreductive Activation of PA-824

Structure. 2012 Jan 11;20(1):101-12. doi: 10.1016/j.str.2011.11.001.


Tuberculosis continues to be a global health threat, making bicyclic nitroimidazoles an important new class of therapeutics. A deazaflavin-dependent nitroreductase (Ddn) from Mycobacterium tuberculosis catalyzes the reduction of nitroimidazoles such as PA-824, resulting in intracellular release of lethal reactive nitrogen species. The N-terminal 30 residues of Ddn are functionally important but are flexible or access multiple conformations, preventing structural characterization of the full-length, enzymatically active enzyme. Several structures were determined of a truncated, inactive Ddn protein core with and without bound F(420) deazaflavin coenzyme as well as of a catalytically competent homolog from Nocardia farcinica. Mutagenesis studies based on these structures identified residues important for binding of F(420) and PA-824. The proposed orientation of the tail of PA-824 toward the N terminus of Ddn is consistent with current structure-activity relationship data.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Flavins / metabolism
  • Models, Molecular*
  • Molecular Sequence Data
  • Molecular Structure
  • Mutagenesis
  • Mycobacterium tuberculosis / enzymology*
  • Nitroimidazoles / metabolism
  • Nitroreductases / chemistry*
  • Nitroreductases / genetics
  • Nitroreductases / metabolism*
  • Protein Binding
  • Protein Conformation*
  • Reactive Nitrogen Species / metabolism


  • Flavins
  • Nitroimidazoles
  • Reactive Nitrogen Species
  • 5-deazaflavin
  • Nitroreductases