Functional analysis of the highly antigenic outer capsid protein, Hoc, a virus decoration protein from T4‐like bacteriophages
Open Access
- 5 July 2010
- journal article
- Published by Wiley in Molecular Microbiology
- Vol. 77 (2), 444-455
- https://doi.org/10.1111/j.1365-2958.2010.07219.x
Abstract
Bacteriophage T4 is decorated with 155 copies of the highly antigenic outer capsid protein, Hoc. The Hoc molecule (40 kDa) is present at the centre of each hexameric capsomer and provides a good platform for surface display of pathogen antigens. Biochemical and modelling studies show that Hoc consists of a string of four domains, three immunoglobulin (Ig)‐like and one non‐Ig domain at the C‐terminus. Biochemical data suggest that the Hoc protein has two functional modules, a capsid binding module containing domains 1 and 4 and a solvent‐exposed module containing domains 2 and 3. This model is consistent with the dumbbell‐shaped cryo‐EM density of Hoc observed in the reconstruction of the T4 capsid. Mutagenesis localized the capsid binding site to the C‐terminal 25 amino acids, which are predicted to form two β‐strands flanking a capsid binding loop. Mutations in the loop residues, ESRNG, abolished capsid binding, suggesting that these residues might interact with the major capsid protein, gp23*. With the conserved capsid binding module forming a foothold on the virus and the solvent‐exposed module able to adapt to bind to a variety of surfaces, Hoc probably provides survival advantages to the phage, such as increasing the virus concentration near the host, efficient dispersion of the virus and exposing the tail for more efficient contact with the host cell surface prior to infection.Keywords
This publication has 53 references indexed in Scilit:
- Structure of the Small Outer Capsid Protein, Soc: A Clamp for Stabilizing Capsids of T4-like PhagesJournal of Molecular Biology, 2010
- Bacteriophage lambda stabilization by auxiliary protein gpD: Timing, location, and mechanism of attachment determined by cryo-EMStructure, 2008
- Assembly of the Small Outer Capsid Protein, Soc, on Bacteriophage T4: A Novel System for High Density Display of Multiple Large Anthrax Toxins and Foreign Proteins on Phage CapsidJournal of Molecular Biology, 2007
- Multicomponent anthrax toxin display and delivery using bacteriophage T4Vaccine, 2007
- Assembly of Human Immunodeficiency Virus (HIV) Antigens on Bacteriophage T4: a Novel In Vitro Approach To Construct Multicomponent HIV VaccinesJournal of Virology, 2006
- Ig-Like Domains on Bacteriophages: A Tale of Promiscuity and DeceitJournal of Molecular Biology, 2006
- UCSF Chimera?A visualization system for exploratory research and analysisJournal of Computational Chemistry, 2004
- Functional analysis of the DNA-packaging/terminase protein gp17 from bacteriophage T4Journal of Molecular Biology, 1998
- The Immunoglobulin Fold: Structural Classification, Sequence Patterns and Common CoreJournal of Molecular Biology, 1994
- The two dispensable structural proteins (soc and hoc) of the T4 phage capsid; their purification and properties, isolation and characterization of the defective mutants, and their binding with the defective heads in vitroJournal of Molecular Biology, 1977