Dataset Information

Bacteriophage P22 capsid size determination: roles for the coat protein telokin-like domain and the scaffolding protein amino-terminus.

ABSTRACT: Assembly of icosahedral capsids of proper size and symmetry is not understood. Residue F170 in bacteriophage P22 coat protein is critical for conformational switching during assembly. Substitutions at this site cause assembly of tubes of hexamerically arranged coat protein. Intragenic suppressors of the ts phenotype of F170A and F170K coat protein mutants were isolated. Suppressors were repeatedly found in the coat protein telokin-like domain at position 285, which caused coat protein to assemble into petite procapsids and capsids. Petite capsid assembly strongly correlated to the side chain volume of the substituted amino acid. We hypothesize that larger side chains at position 285 torque the telokin-like domain, changing flexibility of the subunit and intercapsomer contacts. Thus, a single amino acid substitution in coat protein is sufficient to change capsid size. In addition, the products of assembly of the variant coat proteins were affected by the size of the internal scaffolding protein.

SUBMITTER: Suhanovsky MM

PROVIDER: S-EPMC3163742 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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Bacteriophage P22 capsid size determination: roles for the coat protein telokin-like domain and the scaffolding protein amino-terminus.

Suhanovsky Margaret M MM Teschke Carolyn M CM

Virology 20110723 2

Assembly of icosahedral capsids of proper size and symmetry is not understood. Residue F170 in bacteriophage P22 coat protein is critical for conformational switching during assembly. Substitutions at this site cause assembly of tubes of hexamerically arranged coat protein. Intragenic suppressors of the ts phenotype of F170A and F170K coat protein mutants were isolated. Suppressors were repeatedly found in the coat protein telokin-like domain at position 285, which caused coat protein to assembl ...[more]

PMID: 21784500

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Project description:Icosahedral virus assembly requires a series of concerted and highly specific protein-protein interactions to produce a proper capsid. In bacteriophage P22, only coat protein (gp5) and scaffolding protein (gp8) are needed to assemble a procapsid-like particle, both in vivo and in vitro. In scaffolding protein's coat binding domain, residue R293 is required for procapsid assembly, while residue K296 is important but not essential. Here, we investigate the interaction of scaffolding protein with acidic residues in the N-arm of coat protein, since this interaction has been shown to be electrostatic. Through site-directed mutagenesis of genes 5 and 8, we show that changing coat protein N-arm residue 14 from aspartic acid to alanine causes a lethal phenotype. Coat protein residue D14 is shown by cross-linking to interact with scaffolding protein residue R293 and, thus, is intimately involved in proper procapsid assembly. To a lesser extent, coat protein N-arm residue E18 is also implicated in the interaction with scaffolding protein and is involved in capsid size determination, since a cysteine mutation at this site generated petite capsids. The final acidic residue in the N-arm that was tested, E15, is shown to only weakly interact with scaffolding protein's coat binding domain. This work supports growing evidence that surface charge density may be the driving force of virus capsid protein interactions.Bacteriophage P22 infects Salmonella enterica serovar Typhimurium and is a model for icosahedral viral capsid assembly. In this system, coat protein interacts with an internal scaffolding protein, triggering the assembly of an intermediate called a procapsid. Previously, we determined that there is a single amino acid in scaffolding protein required for P22 procapsid assembly, although others modulate affinity. Here, we identify partners in coat protein. We show experimentally that relatively weak interactions between coat and scaffolding proteins are capable of driving correctly shaped and sized procapsids and that the lack of these proper protein-protein interfaces leads to aberrant structures. The present work represents an important contribution supporting the hypothesis that virus capsid assembly is governed by seemingly simple interactions. The highly specific nature of the subunit interfaces suggests that these could be good targets for antivirals.

Dataset Information

Bacteriophage P22 capsid size determination: roles for the coat protein telokin-like domain and the scaffolding protein amino-terminus.

Publications

Bacteriophage P22 capsid size determination: roles for the coat protein telokin-like domain and the scaffolding protein amino-terminus.

Similar Datasets

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