2X1J

H71A mutant of the antibiotic resistance protein NimA from Deinococcus radiodurans

Summary for 2X1J

• Entry DOI: 10.2210/pdb2x1j/pdb
• Related: 1W3O 1W3P 1W3Q 1W3R 2VPA 2X1K
• Descriptor: NIMA-RELATED PROTEIN, ACETATE ION (3 entities in total)
• Functional Keywords: antibiotic resistance, oxidoreductase
• Biological source: DEINOCOCCUS RADIODURANS
• Total number of polymer chains: 1
• Total formula weight: 24441.17

Authors

Leiros, H.S.,Brandsdal, B.O.,McSweeney, S.M. (deposition date: 2010-01-07, release date: 2010-11-17, Last modification date: 2023-12-20)

Primary citation

Leiros, H.S.,Brandsdal, B.O.,Mcsweeney, S.M.
Biophysical Characterization and Mutational Analysis of the Antibiotic Resistance Protein Nima from Deinococcus Radiodurans.
Biochim.Biophys.Acta, 1804:967-, 2010

PubMed Abstract: Metronidazole (MTZ) is an antibiotic commonly used to treat anaerobic bacterial infections in humans and animals. Antibiotic resistance toward this class of 5-nitroimidazole (5-Ni) drug derivatives has been related to the Nim genes thought to encode a reductase. Here we report the biophysical characteristics of the NimA protein from Deinococcus radiodurans (DrNimA) binding to MTZ and three other 5-Ni drugs. The interaction energies of the protein and antibiotic are studied by isothermal titration calorimetry (ITC) and with free energy and linear interaction energy (LIE) calculations, where the latter method revealed that the antibiotic binding is mainly of hydrophobic character. ITC measurements further found that one DrNimA dimer has two antibiotic binding sites which were not affected by mutation of the reactive His71. The observed association constants (K(a)) were in the range of 5.1-4910(4)M(-1) and the enthalpy release upon binding to DrNimA for the four drugs studied was relatively low (approximately -1 kJ/mol) but still measurable. The drug binding is mainly entropy driven and along with the hydrophobic drug binding site found by crystallography, this possibly explains the low observed enthalpy values. The effect of the His71 mutation and the presence of MTZ were studied by differential scanning calorimetry (DSC). Native DrNimA is a yellow colored protein where the interaction from His71 to the cofactor is thought to be responsible for the coloring. Mutations of His71 to Ala, Ser, Leu or Asp all gave transparent, colorless protein solutions, and the two mutant crystal structures of DrNimA-H71A and DrNimA-H71S presented revealed no cofactor binding.

PubMed: 20096385
DOI: 10.1016/J.BBAPAP.2010.01.010

Experimental method

X-RAY DIFFRACTION (1.9 Å)