Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism
Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism
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DOI：
10.5483/bmbrep.2012.45.4.259
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发表时间：
2012-04-30
期刊：
影响因子：
3.8
通讯作者：
Malys, Naglis
中科院分区：
文献类型：
--
作者：
Davies, Oluwafemi;Mendes, Pedro;Malys, Naglis
修饰核苷酸的积累不利于各种细胞过程，特别是涉及DNA和RNA的过程。为了生存，生物体拥有许多(脱氧)核苷酸磷酸水解酶，这些酶将这些核苷酸从活性的NTP和dNTP池中移除。嘌呤碱基的脱氨基可导致ITP、dITP、XTP和dXTP等核苷酸的积累。E.coliRdgB的特征是一种能作用于这些核苷酸的脱氧核糖核苷三磷酸焦磷水解酶。对YJR069C编码的酿酒酵母(S.cerevisiae)同源物进行纯化，并用15个核苷酸底物测定其(D)NTPase活性。确定了ITP、dITP和XTP为主要底物，并测定了动力学参数。建立三磷酸腺苷、二磷酸腺苷和三磷酸鸟苷的抑制作用。在实验和文献数据的基础上，对ITP、dITP、XTP和dXTP的代谢进行了建模和模拟。(D)ITP/(D)XTPase是具有多底物专一性的酶的新例子，表明多专一性并不罕见[BMB Reports 2012；45(4)：259-264]
Accumulation of modified nucleotides is defective to various cellular processes, especially those involving DNA and RNA. To be viable, organisms possess a number of (deoxy)nucleotide phosphohydrolases, which hydrolyze these nucleotides removing them from the active NTP and dNTP pools. Deamination of purine bases can result in accumulation of such nucleotides as ITP, dITP, XTP and dXTP. E. coli RdgB has been characterised as a deoxyribonucleoside triphosphate pyrophosphohydrolase that can act on these nucleotides. S. cerevisiae homologue encoded by YJR069C was purified and its (d)NTPase activity was assayed using fifteen nucleotide substrates. ITP, dITP, and XTP were identified as major substrates and kinetic parameters measured. Inhibition by ATP, dATP and GTP were established. On the basis of experimental and published data, modelling and simulation of ITP, dITP, XTP and dXTP metabolism was performed. (d)ITP/(d)XTPase is a new example of enzyme with multiple substrate-specificity demonstrating that multispecificity is not a rare phenomenon [BMB reports 2012; 45(4): 259-264]