May be involved in the GO system responsible for removing an oxidatively damaged form of guanine (7,8-dihydro-8-oxoguanine, 8-oxo-dGTP) from DNA and the nucleotide pool. 8-oxo-dGTP is inserted opposite dA and dC residues of template DNA with almost equal efficiency thus leading to A.T to G.C transversions. MutT specifically degrades 8-oxo-dGTP to the monophosphate (By similarity). Functions, in conjunction with ytkD, to protect vegetatively growing cells from DNA-damaging agents such as H(2)O(2) or t-BHP (t-butylhydroperoxide). The 2 proteins do not however protect spores. 8-oxo-dGTP + H2O = 8-oxo-dGMP + diphosphate + H(+) Growing cells lacking this gene have an unchanged spontaneous mutation frequency, even in triple mutT/yjhB/yvcI disruptions (PubMed:12483591), however they are more sensitive to DNA-damaging agents such as H(2)O(2) or t-BHP (PubMed:16513759). A double ytkD/mutT disruption has a greater mutation frequency than the ytkD disruption, as well as an increased sensitivity to DNA-damaging agents (PubMed:16513759). These properties are also seen in stationary phase cells (PubMed:19011023). Belongs to the Nudix hydrolase family.