Mikhail M. Ivanov; Daria V. Dibrova
Faculty of Bioengineering and Bioinformatics Lomonosov Moscow State University; Belozersky Institute of Physico-Chemical Biology Lomonosov Moscow State University
ivamikem@gmail.com
Based on current understanding, mitochondria originated from a bacterial ancestor and were acquired by the proto-eukaryotic cell as a result of a single endosymbiotic event. During evolution, mitochondrial genomes, which originally contained a complete set of bacterial genes, underwent significant reduction, either through gene loss or through their unidirectional transfer to the nuclear genome. The degree and nature of mitogenome reduction varied significantly between taxonomic groups of eukaryotes. For example, animal mitochondrial genomes are much more compact than those of fungi or plants. As a result of this diversity of mitogenomes, rare genes in them remain poorly characterized and require further study.
The aim of this work was to search for and perform phylogenetic analysis of rare protein-coding genes in the mitochondrial genomes of various photosynthetic organisms.
The study analyzed the mitogenomes of 1,049 species of green plants, red algae, ochrophyta, and photosynthetic protozoa. In our laboratory, based on data from E.V. Kunin’s group, 140 protein HMM profiles, known as MitoCOGs, were formed and divided into five functional groups. Using these profiles, approximately 40,000 proteins from mitogenomes were analyzed. Proteins that had no matches among MitoCOGs were additionally compared with conventional prokaryotic COGs. As a result, proteins with established similarities were distributed among functional groups, and the remaining approximately 6,000 proteins were subjected to clustering.
The results obtained indicate the similarity of the mitochondrial genomes of photosynthetic organisms in terms of composition, both within individual taxonomic groups and between them. At the same time, a significant number of proteins that cannot be attributed to any of the common families from mitogenomes were found in all the groups studied, indicating the need for more detailed inspection.