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Structure of Mycobacterium tuberculosis nucleoside diphosphate kinase R80N mutant in complex with citrate
Author(s) -
Georgescauld Florian,
Moynié Lucile,
Habersetzer Johann,
Dautant Alain
Publication year - 2014
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x13034134
Subject(s) - random hexamer , salt bridge , nucleotide , chemistry , hydrogen bond , nucleoside , mutant , thermal stability , crystallography , stereochemistry , biochemistry , molecule , organic chemistry , gene
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 ( T m = 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.