Mitokondri genomundan evrimsel olarak nükleer genoma transfer olan genlerde kodon kullanım farkına bağlı mutasyon etkisi
Özet
The size of mitochondrial genome was reduced during the evolutionary process because of horizontal gene transfer to nucleus. Human mitochondrial DNA (mtDNA) encodes only 13 proteins. MtDNA of Reclinomonas americana (R. americana) is one of the biggest mitochondrial genomes representing very early stages of mtDNA evolution. Human mtDNA has some differences in codon reassignment from R. americana mtDNA which uses standart genetic code. This study compared i) R. americana and human mtDNA, ii) 25 subunits of oxidative phosphorylation complexes encoded by R. americana mtDNA and their both mitochondrial and nuclear orthologs in humans at nucleotide and amino acid level. The similarity of mtDNA in these organisms exists only in only one short region which is a part of COX3 gene. The similarity at protein level is more conserved than DNA level. Human nuclear orthologs of R. americana mtDNA genes were more similar than mitochondrial orthologs. The results of this study suggest that mitochondrial DNA has a higher mutation rate than nuclear DNA, the evolutionary change of human mitochondrial genetic code had mutational consequences and this change is likely one of the barriers in the transfer of mitochondrial genome to nucleus.