Comparative characterization of release factor RF-3 genes of Escherichia coli, Salmonella typhimurium, and Dichelobacter nodosus.
The termination of protein synthesis in bacteria requires two codon-specific release factors, RF-1 and RF-2. A gene for a third factor, RF-3, that stimulates the RF-1 and RF-2 activities has been isolated from the gram-negative bacteria Escherichia coli and Dichelobacter nodosus. In this work, we isolated the RF-3 gene from Salmonella typhimurium and compared the three encoded RF-3 proteins by immunoblotting and intergeneric complementation and suppression. A murine polyclonal antibody against E. coli RF-3 reacted with both S. typhimurium and D. nodosus RF-3 proteins. The heterologous RF-3 genes complemented a null RF-3 mutation of E. coli regardless of having different sequence identities at the protein level. Additionally, multicopy expression of either of these RF-3 genes suppressed temperature-sensitive RF-2 mutations of E. coli and S. typhimurium by restoring adequate peptide chain release. These findings strongly suggest that the RF-3 proteins of these gram-negative bacteria share common structural and functional domains necessary for RF-3 activity and support the notion that RF-3 interacts functionally and/or physically with RF-2 during translation termination.
Kawazu
Y
Y
Department of Tumor Biology, University of Tokyo, Japan.
Ito
K
K
Matsumura
K
K
Nakamura
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D006090:Gram-Negative Bacteria / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010454:Peptide Termination Factors / Q000096:biosynthesis / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013489:Suppression, Genetic; D013696:Temperature
D010454:Peptide Termination Factors; C041460:peptide chain termination release factor 2; C087971:peptide-chain-release factor 3