Mutations that increase the affinity of a translational repressor for RNA.
The coat protein of the RNA bacteriophage MS2 is a specific RNA binding protein that represses translation of the viral replicase gene during the infection cycle. As an approach to characterizing the RNA-binding site of coat protein we have isolated a series of coat mutants that suppress the effects of a mutation in the translational operator. Each of the mutants exhibits a super-repressor phenotype, more tightly repressing both the mutant and wild-type operators than does the wild-type protein. The variant coat proteins were purified and subjected to filter binding assays to determine their affinities for the mutant and wild-type operators. Each protein binds the operators from 3 to 7.5-fold more tightly than normal coat protein. The amino acid substitutions seem to extend the normal binding site by introducing new interactions with RNA.
Lim
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Department of Cell Biology, University of New Mexico School of Medicine, Albuquerque 87131.
Peabody
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DS
D001483:Base Sequence; D002213:Capsid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D017909:Levivirus / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D013489:Suppression, Genetic
D012367:RNA, Viral; D016601:RNA-Binding Proteins; D012324:RNA-Dependent RNA Polymerase