PMID: 2108146Apr 5, 1990Paper

Translational repression by bacteriophage MS2 coat protein expressed from a plasmid. A system for genetic analysis of a protein-RNA interaction.

The Journal of Biological Chemistry
D S Peabody

Abstract

The coat protein of bacteriophage MS2 is a translational repressor. It inhibits the synthesis of the viral replicase by binding a specific RNA structure that contains the replicase translation initiation region. In order to begin a genetic dissection of the repressor activity of coat protein, a two-plasmid system has been constructed that expresses coat protein and a replicase-beta-galactosidase fusion protein from different, compatible plasmids containing different antibiotic-resistant determinants. The coat protein expressed from the first plasmid (pCT1) represses synthesis of a replicase-beta-galactosidase fusion protein encoded on the other plasmid (pRZ5). Mutations in the translational operator or in coat protein result in constitutive synthesis of the enzyme. This permits the straightforward isolation of mutations in the coat sequence that affect repressor function. Because of the potential importance of cysteine residues for RNA binding, mutations were constructed that substitute serines for the cysteine residues normally present at positions 46 and 101. Both of these mutations result in translational repressor defects. Chromatographic and electron microscopic analyses indicate that the plasmid-encoded wild-type coat pro...Continue Reading

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