Описаны филогенетические взаимоотношения между легумаинами прокариот, древних эукариот, растений и животных. Прослежен эволюционный путь легумаинов растений, начинающийся от ряда древних эукариот и далее соответствующий последовательным этапам формирования растительных организмов – зеленые водоросли классов Chlorophyta и затем Charophyta, мхи и семенные растения.

Cysteine proteinases of unique Asn/Asp specificity (legumains) were first detected and studied as enzymes catalyzing proteolytic processing of seed storage globulins and their further degradation during seed germination. For the moment, it is known that legumains are characteristic both of plants and of a wide range of animals, several ancient eukaryotes as well as of bacteria and archaea. Because of their narrow specificity, legumains catalyze a wide range of processes related to plant and animal vital functions. Eukaryote legumains are synthesized as inactive precursors containing conserved N- and C-terminal domains and a rather variable activation peptide in between. Activation of plant seed and mammalian legumains occurs due to autocatalytic cleavage inside the activation peptide followed by detachment of the C-terminal domain that blocks the active site amino acids positioned inside the N-terminal domain. In contrast to eukaryote legumains, prokaryote legumains lack the C-terminal domain. For the moment, a wide range of amino acid sequences of plant and animal legumains as well as legumains from ancient eukaryotes and prokaryotes became available. Therefore, a detail analysis of successive evolutionary stages of plant legumains was conducted in this investigation. When amino sequences of legumains from Arabidopsis thaliana and Homo sapience were used as queries, a wide collection of seed legumains and their precursors from spore plants, animal legumains as well as legumains from ancient eukaryotes and prokaryotes was collected. To follow evolutionary pathway of plant and animal legumains full-length amino acid sequence of legumains from Trichomonas species estimated as most ancient organism among eukaryotes were used as roots. Three basic clusters were detected in respective evolutionary tree: the ancient group of Alveolata and Stramenopiles legumains, Plant and Metazoa legumains. The same clusters were observed when the sequence region analyzed was restricted to the N-terminal domains and prokaryote legumains were used as roots. Legumain sequences within plant cluster strongly follow the evolutionary pathway of species: green algae, mosses, seed plants. Exon/intron structures of legumain genes from land plants are almost identical and close to that of Klebsormidium nitens legumain (green alga, Charophyta). In contrast, position of introns in Chlorophyta legumain genes is completely different. Additionally, long variable inserts inside the C-terminal domain are specifically characteristic of amino acid sequences only from Chlorophyta legumain species. These observations both are in line with the plant tree of life, estimated Chlorophyta as most ancient green algae.