title: Structure of Mycobacterium tuberculosis nucleoside diphosphate kinase R80N mutant in complex with citrate.
abstract: The crystal structure of the wild-type nucleoside diphosphate kinase from Mycobacterium tuberculosis at 2.6 Å resolution revealed that the intersubunit salt bridge Arg80-Asp93 contributes to the thermal stability of the hexamer (Tm = 76°C). On mutating Asp93 to Asn to break the salt bridge, the thermal stability dramatically decreased by 27.6°C. Here, on mutating Arg80 to Asn, the thermal stability also significantly decreased by 8.0°C. In the X-ray structure of the R80N mutant solved at 1.9 Å resolution the salt bridge was replaced by intersubunit hydrogen bonds that contribute to the thermal stability of the hexamer. A citrate anion from the crystallization buffer was bound at the bottom of the nucleotide-binding site via electrostatic and hydrogen-bonding interactions with six conserved residues involved in nucleotide binding. Structural analysis shows that the citrate is present at the location of the nucleotide phosphate groups.
authors.affiliation: Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Georgescauld
authors.affiliation: Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France.
authors.forename: Lucile
authors.initials: L
authors.lastname: Moynié
authors.affiliation: Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France.
authors.forename: Johann
authors.initials: J
authors.lastname: Habersetzer
authors.affiliation: Institut de Biochimie et de Génétique Cellulaires, UMR 5095, CNRS, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Dautant
mesh_terms: D019943:Amino Acid Substitution; D019343:Citric Acid / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D050505:Mutant Proteins / Q000737:chemistry* / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D009701:Nucleoside-Diphosphate Kinase / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D055672:Static Electricity
chemical_list: D050505:Mutant Proteins; D021122:Protein Subunits; D019343:Citric Acid; D009701:Nucleoside-Diphosphate Kinase
keywords: Mycobacterium tuberculosis; nucleoside diphosphate kinase; thermal stability