Structural Basis of 5-Nitroimidazole Antibiotic Resistance: The Crystal Structure of Nima from Deinococcus RadioduransLeiros, H.-K.S., Kozielski-Stuhrmann, S., Kapp, U., Terradot, L., Leonard, G.A., Mcsweeney, S.M.
(2004) J Biol Chem 279: 55840
- PubMed: 15492014
- DOI: https://doi.org/10.1074/jbc.M408044200
- Primary Citation of Related Structures:
1W3O, 1W3P, 1W3Q, 1W3R
- PubMed Abstract:
5-Nitroimidazole-based antibiotics are compounds extensively used for treating infections in humans and animals caused by several important pathogens. They are administered as prodrugs, and their activation depends upon an anaerobic 1-electron reduction of the nitro group by a reduction pathway in the cells. Bacterial resistance toward these drugs is thought to be caused by decreased drug uptake and/or an altered reduction efficiency. One class of resistant strains, identified in Bacteroides, has been shown to carry Nim genes (NimA, -B, -C, -D, and -E), which encode for reductases that convert the nitro group on the antibiotic into a non-bactericidal amine. In this paper, we have described the crystal structure of NimA from Deinococcus radiodurans (drNimA) at 1.6 A resolution. We have shown that drNimA is a homodimer in which each monomer adopts a beta-barrel fold. We have identified the catalytically important His-71 along with the cofactor pyruvate and antibiotic binding sites, all of which are found at the monomer-monomer interface. We have reported three additional crystal structures of drNimA, one in which the antibiotic metronidazole is bound to the protein, one with pyruvate covalently bound to His-71, and one with lactate covalently bound to His-71. Based on these structures, a reaction mechanism has been proposed in which the 2-electron reduction of the antibiotic prevents accumulation of the toxic nitro radical. This mechanism suggests that Nim proteins form a new class of reductases, conferring resistance against 5-nitroimidazole-based antibiotics.
Macromolecular Crystallography Group, European Synchrotron Radiation Facility, BP 220, 6 Rue Jules Horowitz, F-38043 Grenoble Cedex 09, France.