Location of the Bacteriophage P22 Coat Protein C-Terminus Provides Opportunities for the Design of Capsid-Based Materials

Abstract

Rational design of modifications to the interior and exterior surfaces of virus-like particles (VLPs) for future therapeutic and materials applications is based on structural information about the capsid. Existing cryo-electron microscopy based models suggest that the C-terminus of the bacteriophage P22 coat protein (CP) extends towards the capsid exterior. Our biochemical analysis through genetic manipulations of the C-terminus supports the model where the CP C-terminus is exposed on the exterior of the P22 capsid. Capsids displaying a 6xHis tag appended to the CP C-terminus bind to a Ni affinity column, and the addition of positively or negatively charged coiled coil peptides to the capsid results in association of these capsids upon mixing. Additionally, a single cysteine appended to the CP C-terminus results in the formation of intercapsid disulfide bonds and can serve as a site for chemical modifications. Thus, the C-terminus is a powerful location for multivalent display of peptides that facilitate nanoscale assembly and capsid modification.

Modular Self-Assembly of Protein Cage Lattices for Multistep Catalysis

“…Two repeats of a net negatively charged peptide with sequence VAALEKE (E2 peptide) was introduced at the C-terminus of the CP (hereafter referred to as CP-E2). Because the P22 VLP is constituted with 420 copies of CP and the C-terminus of CP is known to be exposed to the exterior of the capsid, 40 420 copies of the E2 peptide is displayed on the outside of the P22 VLP for the mutant. The P22 VLPs with the E2 peptide is referred to as P22-E2.…”

Bacteriophage lambda: Early pioneer and still relevant

“…Lambda and P22 have been developed into powerful and versatile protein display agents, where both the head decoration proteins lambda D (Sternberg and Hoess, 1995; Mikawa et al , 1996; Nicastro et al , 2013; Chang et al , 2014) and P22 Dec (Parent et al , 2012b), as well as the lambda major tail V protein (Maruyama et al , 1994; Zanghi et al , 2007) and P22 MCP head protein (Kang et al , 2008; Servid et al , 2013) have been used successfully to display foreign peptides and proteins. Lambda virions have also been used as DNA or protein vaccine delivery vehicles in mammals (Jepson and March, 2004; Lankes et al , 2007; Clark et al , 2011; Mattiacio et al , 2011; Saeedi et al , 2014).…”

Engineering virus-like particles as vaccine platforms

“…The process is compatible with GMP manufacture, and in fact several Qβ VLP-based vaccines have been tested in clinical trials [15–17]. However, VLPs can also be engineered to contain these convenient sites, such as the engineering a surface-exposed cysteine or lysine into the VLP, providing accessible reactive groups [18–20] (Fig. 1).…”

“…Nevertheless, as the repertoire of solved molecular structures is expanded and our understanding of how these structures form improves, rational design of VLPs that include these molecular structures will expand. This is highlighted by recent efforts to add coiled-coil domains to P22 bacteriophage VLPs to aid in folding and display of large foreign antigens [20]. Rationally designing hybrid protein structures based on the building blocks found in nature will drive the field toward more stable and versatile VLP vaccine platforms and recent efforts to use computational modeling to predict whether peptides are compatible with VLP assembly may also improve success rates [42–46].…”