[Contexts of initiation codons of tobamo- and potexvirus genes translation]

The contexts of translation initiation codon (the nucleotide sequences surrounding the AUG) have been analyzed by computer in 15 tobamoviruses (45 genes) and 22 potexviruses (110 genes). The results obtained indicate both high key similarity and some differences between viral and eukaryotic AUG contexts. The similar features are: the localization of coinciding nucleotides near the start codon (in -3... +18 positions), purines presence in position (-3... +18) and guanine in position +4 (+4G) relative to codon AUG as well as the similarity of viral translation contexts to corresponding context sequences of vertebrates (16.9-52.4%), monocot (21.9-41.2%) and dicot plants (39.3-74.3%). The distinctive features of viral translation initiation contexts are a high frequency of +5C, -5Y and +10R components as well as a broad variation of context elements between various viruses and/or genes. So, the frequency of +5C varied between 0% (TGB1 genes) and 100% (Re genes), the -5Y--from 22% (TGB2 genes) to 86% (Mp genes), the +10R--between 22% (TGB2 genes) and 93% (Mp genes), and the frequency of eukaryotic Kozak contexts varied from 5% (TGB2 genes) to 87% (Mp genes). The test proposed to compare a similarity between translation initiation contexts and their known consensus sequences are discussed.