Effects of an early conformational switch defect during ϕX174 morphogenesis are belatedly manifested late in the assembly pathway.

ABSTRACT: C-terminal, aromatic amino acids in the ϕX174 internal scaffolding protein B mediate conformational switches in the viral coat protein. These switches direct the coat protein through early assembly. In addition to the aromatic amino acids, two acidic residues, D111 and E113, form salt bridges with basic, coat protein side chains. Although salt bridge formation did not appear to be critical for assembly, the substitution of an aromatic amino acid for D111 produced a lethal phenotype. This side chain is uniquely oriented toward the center of the coat-scaffolding binding pocket, which is heavily dominated by aromatic ring-ring interactions. Thus, the D111Y substitution may restructure pocket contacts. Previously characterized B(-) mutants blocked assembly before procapsid formation. However,

SUBMITTER: Gordon EB 

PROVIDER: S-EPMC3571406 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature