Heart Mitochondrial TTP Synthesis and the Compartmentalization of TMP

• DOI: 10.1074/jbc.m114.624213
• Publication Date: 2014-12-12T01:24:37Z
• Authors: Vasudeva G. Kamath; Chia-Heng Hsiung; Zachary J. Lizenby; Edward E. McKee
• Keywords: Thymidine; Nucleotide salvage; Thymidine kinase

The primary pathway of TTP synthesis in the heart requires thymidine salvage by mitochondrial kinase 2 (TK2). However, compartmentalization this and transport nucleotides are not well understood. We investigated metabolism [3H]thymidine or [3H]TMP as precursors [3H]TTP isolated intact broken mitochondria from rat heart. results demonstrated that was readily metabolized enzymes to mitochondria. equivalent addition produced far less than amount observed with precursor. Using zidovudine inhibit TK2, effectively blocked, demonstrating arose solely dephosphorysynthase includes deoxyuridine triphosphatelation [3H]thymidine. To determine role membrane TMP metabolism, membranes were disrupted freezing thawing. In mitochondria, converted [3H]TMP, but further phosphorylation prevented even though energy charge maintained oligomycin A, phosphocreatine, creatine phosphokinase. failure synthesize related a loss potential inhibition electron chain, confirmed carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone potassium cyanide, respectively, summary, these data, taken together, suggest is compartmentalized so prefers synthesized TK2 over medium mitochondria.The ability serve precursor understood.ResultsTMP cannot be except breakdown mitochondria.ConclusionThymidine sole source for matrix.SignificanceThymidine crucial understand DNA depletion diseases caused (TK2) deficiency. Thymidine matrix.