[Translation of RNA 4 from plant brome mosaic virus in an Escherichia coli cell-free system with pure protein factors in translation].

Translation by RNA 4 from plant brome mosaic virus coding for the virus coat protein in an E. coli cell-free system with pure factors of translation has been studied. It has been shown that the initiation of translation by this mRNA depends completely on the three E. coli initiation factors. Optimal ionic conditions for the formation of the initiatory 70S times fMet-tRNA times RNA 4 complex have been found. It has been shown that this complex is stable in conditions of zonal centrifugation. On the basis of reaction with puromycin it has been determined that the initiatory fMet-tRNA in this complex occupies the donor-tRNA-binding site of the ribosome. By the competence of the initiatory ribosomal complex for binding with Ser-tRNA (serine is the N-terminal amino acid in the virus coat protein) it can be concluded that the ribosomal and the E. coli initiation factors recognize the initiatory codon of the RNA r from brome mosaic virus. Peptide synthesis induced by RNA 4 has been obtained on E. coli ribosomes with five pure factors of translation: IF-1, IF-2A, IF-3, EF-Tu or (Tu--Ts) and EF-G. The dependence of elongation on the Mg2+ concentration in the medium at RNA 4 translation has been determined.