Elongation of displacement-loop strands in human and mouse mitochondrial DNA is arrested near specific template sequences.
Animal mitochondrial DNA (mtDNA) maintains a displacement loop (D loop) at the heavy strand origin of replication. These D loops represent sharply limited synthesis of heavy strands and provide a unique opportunity to examine the termination of DNA synthesis. Direct sizing at the nucleotide level indicates that the 3' ends of D-loop strands of human and mouse mtDNA are discrete and map within three to five nucleotides on the complementary template strand. In the case of human mtDNA, there is a single trinucleotide stop point 51-53 nucleotides downstream from a 15-nucleotide template sequence (3'T-A-A-C-C-C-A-A-A-A-A-T-A-C-A 5') which is repeated four times in the mouse mtDNA D-loop region 3'(T-A-A-Py-Py-A-A-A-T-T-A-C-A 5'). The stop points of the five major mouse D-loop strands are 24-63 nucleotides downstream from the four repeated template sequences. These results suggest that the arrest of D-loop strand elongation is an event determined by template sequence.
D000818:Animals; D001483:Base Sequence; D002277:Carcinoma; D002460:Cell Line; D004262:DNA Restriction Enzymes; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D007739:L Cells; D051379:Mice; D008970:Molecular Weight; D009062:Mouth Neoplasms; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D013698:Templates, Genetic
D004272:DNA, Mitochondrial; D004262:DNA Restriction Enzymes