Messenger ribonucleic acid metabolism in mammalian mitochondria: relationship between the decay of mitochondrial mRNA and their poly(A)

Abstract

The mitochondrial poly(adenylic acid)[A] containing mRNA in mouse [Ehrlich tumor] ascites cells labeled with radioactive precursors contain 35-55 nucleotide long Poly(A) sequences. These sequences shorten with age in cells incubated in cold medium. The possible relationship between the decay rates of mRNA and their poly(A) sequences was investigated by using mitochondrial RNA and protein synthesis inhibitors. The pattern of mRNA decay as determined by a new solid-phase-bound complementary DNA procedure indicates the presence of 2 classes of poly(A)-containing mRNA in mammalian mitochondria: 1 decaying with a t1/2 [half-life] of 45 min and the other class with a t1/2 of 210 min. Inhibitors such as ethidium bromide and puromycin which accelerate the decay of mitochondrial mRNA also cause an enhanced decay of poly(A) sequences. The involvement of poly(A) sequences in the mRNA stability is demonstrated.