Similarity of Mutation Spectra of the Mitochondrial DNA Hypervariable Segment 1 in Homo and Pan Species

The mutation spectrum of mtDNA hypervariable segment 1 (HVS1) was compared for east chimpanzee Pan troglodytes schweigfurthi and human. The two HVS1 had much the same nucleotide composition, and their mutation spectra were similar in major characteristics (substantial prevalence of transitions over transversions, pyrimidine transitions over purine ones, and C T over T C). DNA strand displacement (dislocation) during replication was identified as a major mechanism of context-dependent mutagenesis in human and chimpanzee mtDNAs. Nucleotide positions with mutations fitting the model of dislocation mutagenesis accounted for 21% of all variable positions in the chimpanzee HVS1. Variable motifs proved to be similar in the chimpanzee and human HVS1. Comparison of the Neanderthal and modern human HVS1 nucleotide sequences showed that most variable nucleotides are in DNA sites allowing context-dependent mutagenesis.