Sequence and functional analysis of mutations in the gene encoding peptide-chain-release factor 2 of Escherichia coli.
Mutations in the prfB gene which encodes peptide-chain-release factor 2 of Escherichia coli were defined by DNA sequence analysis. prfB1 and prfB3 substitute lysine and asparagine for glutamate and aspartate at amino acid positions 89 and 143, respectively. Temperature-sensitive mutations, prfB2 and prfB286, each contain the identical substitution of phenylalanine for leucine-328. These mutations suppress UGA but not UAG or UAA. The efficiency of suppression was affected by the neighboring RNA context. The prfB gene encodes a premature UGA stop codon at position 26 and is expressed by +1 frameshifting. The efficiency of natural frameshift was 18% as measured by using the monolysogenic lambda assay vector containing prfB-lacZ fusions, and increased up to 30% in the prfB mutants. These observations can be interpreted as genetic evidence for the autogenous control of RF2 synthesis by frameshifting. Structural and functional organizations of release factors are discussed.
Mikuni
O
O
Department of Tumor Biology, University of Tokyo, Japan.
Kawakami
K
K
Nakamura
Y
Y
D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry; D015139:Blotting, Southern; D003062:Codon; D004926:Escherichia coli / Q000235:genetics*; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000096:biosynthesis / Q000235:genetics*; D014176:Protein Biosynthesis; D013489:Suppression, Genetic
D003062:Codon; D010454:Peptide Termination Factors; C041460:peptide chain termination release factor 2; D001216:Asparagine; D008239:Lysine