Lack of peptide-release activity responding to codon UGA in Mycoplasma capricolum

摘要: In Mycoplasma capricolum, a relative of Gram-positive eubacteria with high genomic AT-content (75%), codon UGA is assigned to tryptophan instead termination signal. Thus, in this bacterium the release factor 2 (RF-2), that recognizes UAA and codons such as Escherichia coli Bacillus subtilis, would be either specific or deleted. To test this, we have constructed cell-free translation system using synthetic mRNA including [mRNA(UAA)], UAG [mRNA(UAG)] [mRNA(UGA)] in-frame. absence tryptophan, mRNA(UGA) ceased at sites without appreciable synthesized peptides from ribosomes, whereas mRNA(UAA) mRNA(UAG) bulk was released. Upon addition E.coli S-100 fraction B.subtilis system, were almost completely released presumably because presence RF-2 active added fraction. These data suggest deleted its activity strongly weakened M.capricolum.