title: Identification of an ITPase/XTPase in Escherichia coli by structural and biochemical analysis.
abstract: Inosine triphosphate (ITP) and xanthosine triphosphate (XTP) are formed upon deamination of ATP and GTP as a result of exposure to chemical mutagens and oxidative damage. Nucleic acid synthesis requires safeguard mechanisms to minimize undesired lethal incorporation of ITP and XTP. Here, we present the crystal structure of YjjX, a protein of hitherto unknown function. The three-dimensional fold of YjjX is similar to those of Mj0226 from Methanococcus janschii, which possesses nucleotidase activity, and of Maf from Bacillus subtilis, which can bind nucleotides. Biochemical analyses of YjjX revealed it to exhibit specific phosphatase activity for inosine and xanthosine triphosphates and have a possible interaction with elongation factor Tu. The enzymatic activity of YjjX as an inosine/xanthosine triphosphatase provides evidence for a plausible protection mechanism by clearing the noncanonical nucleotides from the cell during oxidative stress in E. coli.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Jimin
authors.initials: J
authors.lastname: Zheng
authors.forename: Vinay Kumar
authors.initials: VK
authors.lastname: Singh
authors.forename: Zongchao
authors.initials: Z
authors.lastname: Jia
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism; D007293:Inosine Triphosphate / Q000737:chemistry; D007700:Kinetics; D017017:Methanococcus / Q000201:enzymology / Q000235:genetics; D024101:Mitochondrial Proteins; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D010449:Peptide Mapping; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011755:Pyrophosphatases / Q000737:chemistry*; D012265:Ribonucleotides / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D013329:Structure-Activity Relationship; D013431:Sulfates / Q000737:chemistry / Q000378:metabolism; D000097630:Inosine Triphosphatase
chemical_list: D000255:Adenosine Triphosphate; D000951:Antigens, Neoplasm; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006160:Guanosine Triphosphate; D007293:Inosine Triphosphate; D024101:Mitochondrial Proteins; D010444:Peptide Elongation Factor Tu; D011755:Pyrophosphatases; D012265:Ribonucleotides; D013431:Sulfates; D000097630:Inosine Triphosphatase; C081169:Maf protein, Bacillus subtilis; C091648:TUFM protein, human; C065326:xanthosine 5'-triphosphate; C506894:YjjX protein, E coli