title: A diadenosine 5',5''-P1P4 tetraphosphate (Ap4A) hydrolase from Arabidopsis thaliana that is activated preferentially by Mn2+ ions.
abstract: Asymmetrical diadenosine 5',5''-P(1)P(4) tetraphosphate (Ap(4)A) hydrolases are key enzymes controlling the in vivo concentration of Ap(4)A--an important signaling molecule involved in regulation of DNA replication and repair, signaling in stress response and apoptosis. Sequence homologies indicate that the genome of the model plant Arabidopsis thaliana contains at least three open reading frames encoding presumptive Ap(4)A hydrolases: At1g30110, At3g10620, and At5g06340. In this work we present efficient overexpression and detailed biochemical characteristics of the AtNUDX25 protein encoded by the At1g30110 gene. Aided by the determination of the binding constants of Mn(Ap(4)A) and Mg(Ap(4)A) complexes using isothermal titration calorimetry (ITC) we show that AtNUDX25 preferentially hydrolyzes Ap(4)A in the form of a Mn(2+) complex.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland.
authors.forename: Blanka
authors.initials: B
authors.lastname: Szurmak
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Wysłouch-Cieszyńska
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Wszelaka-Rylik
authors.forename: Wojciech
authors.initials: W
authors.lastname: Bal
authors.forename: Marta
authors.initials: M
authors.lastname: Dobrzańska
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry*; D000246:Adenosine Diphosphate Ribose / Q000737:chemistry; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D002151:Calorimetry / Q000379:methods; D004260:DNA Repair; D004261:DNA Replication; D007477:Ions; D008345:Manganese / Q000737:chemistry*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011755:Pyrophosphatases / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D000096964:Nudix Hydrolases
chemical_list: D017766:Acid Anhydride Hydrolases; D000246:Adenosine Diphosphate Ribose; D007477:Ions; D008345:Manganese; D011755:Pyrophosphatases; D000096964:Nudix Hydrolases; C020023:bis(5'-nucleosyl)tetraphosphatase (asymmetrical)