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TRANSPORT RNA GENES REMOLDING IN MITOCHONDRIAL GENOMES
РЕМОДЛИНГ ГЕНОВ ТРАНСПОРТНЫХ РНК В МИТОХОНДРИАЛЬНЫХ ГЕНОМАХ
E. V. Romanova1, Yu. S. Bukin1, V. V. Aleoshin2, D. Yu. Sherbakov1,3
1Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russian Federation
2Belozersky Institute for Physicochemical Biology, Lomonosov Moscow State University, Moscow 119991, Russian Federation
3Irkutsk State University, Irkutsk 664003, Russian Federation
Majority of metazoan mitochondrial (mt) genomes contain a standard set of 37 genes: 13 protein coding genes, two ribosomal genes and 22 transfer RNAs (tRNAs) genes. Mitochondrial (mt) genomes of four Baikalian amphipod species contain additional tRNA copies. Mt genome of A. victorii has two tRNA-Asp genes, E. vittatus has two tRNA-Pro genes, G.cabanisii has two tRNA-Leu1 genes, G. fasciatus has two tRNA-Gln genes and two tRNA-Val genes. Low degree of sequence similarity between some copies let us assume that tRNA remolding/recruitment (changes of tRNA identity by mutation in its anticodon) happened in some cases. In our work we applied statistics and phylogenetic methods for a robust determination of identity of the duplicated tRNA genes. We defined origination of additional copy of tRNA-Pro of E.vittatus from tRNA-Leu1 duplication. Additional copy of tRNA-Gln of G.fasciatus and tRNA-Asp of A.victorii most probably originated from tRNA-His duplication. A second copy of tRNA-Val of G.fasciatus was found to originate from the copy of tRNA-Ile. Both copies Leu1 of G.cabanisii become identified as result of mere duplication. Presence of additional tRNA genes illustrates the process of active genes rearrangement. Additional tRNA gene copies in mt genomes of Baikalian amphipod seem to be on the different stages of their degeneration. tRNA duplications and remolding are frequently observed in genomes with increased mutation rate. Lake Baikal environment probably promotes the increased level of evolution in mt genomes of endemic amphipods.