[Possible commonality of origin of the RNA polymerase genes of plus-RNA-containing viruses of bacteria, plants and animals].

The data given testify that picornavirus RNA-dependent RNA-polymerase, RNA-polymerase encoded by the genome of MS2 phage and the certain polypeptides involved in the replication of RNA genomes of alphaviruses, tobamoviruses and tricornaviruses include the homologous stretches of the amino acids. The common sequences are located in the COOH-terminal regions of the viral proteins. These sequences have been found to be conserved also in RNA-replicase MS2 phage. The similarity of the primary structure between the RNA-polymerase phages and proteins of eucaryotic plus-RNA-containing viruses testifies in favour of the hypothesis on possible ancestral relationship of virus RNA-polymerases genes. These data point out that it is possible to localize an indispensable functional domain conserved upon evolutionary divergence of an ancestral RNA-polymerase gene. Such conservative region is recently found in the composition of RNA-dependent DNA-polymerases animals and plants virus. An attention is drawn to the region of protein similarity between conservative domains of viral RNA-dependent DNA-polymerases and RNA-polymerases.