Dominance in lambda S mutations and evidence for translational control.
Phenotypic analysis of a collection of point mutations in the lysis gene S of bacteriophage lambda indicates that many of the S alleles exhibit at least partially dominant character, suggesting that the S gene product (gpS) must oligomerize to achieve its lethal membrane effect. Moreover, mutations found 5' to the coding sequence also show a dominant character and appear to define a site, designated sdi (structure directed initiation) where mRNA secondary structure controls the choice of initiation codons. We propose that formation of the sdi structure occludes the consensus Shine-Dalgarno sequence and results in initiation at the Met3 codon, generating a lethal 105 residue polypeptide. The model predicts that, in the absence of the sdi stem-and-loop, initiation occurs at the Met1 codon, generating a 107 residue polypeptide, which is a non-lethal inhibitor of lysis. In support of the model, alteration of the first codon was achieved using site-directed mutagenesis, resulting in an S allele that is more lethal and induces lysis significantly sooner than the wild-type.
Raab
R
R
Department of Biology, Texas A & M University, College Station 77843.
Neal
G
G
Sohaskey
C
C
Smith
J
J
Young
R
R
D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D004279:DNA, Viral; D005799:Genes, Dominant; D005814:Genes, Viral; D008242:Lysogeny; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D014176:Protein Biosynthesis; D014764:Viral Proteins
D004279:DNA, Viral; D014764:Viral Proteins