Fig. 11

Mutations at the Gag–Elp interface or central beta-sheet affect budding and Gag folding. Modelled structure of the FFV Gag–Elp interaction indicates that mutations affecting only budding tend to localize at the Gag–Elp interface. Mutations which also affect Gag processing and capsid assembly localize to the central beta-sheet, therefore likely affecting the overall folding of Gag. The top panel shows a structure of the interaction of FFV Gag (cyan ribbon) and Env (yellow ribbon) modelled using the PFV structure [38] as a template (only one dimer of the dimer–dimer is shown). The eight 5-mers mutated to alanine are colored by phenotype (white, wild-type; blue, no budding; red, no budding, Gag processing or capsid assembly). Side chains of single point mutations in Gag are labelled and shown as sticks colored by atom type (except for glycine C-alpha atoms, shown as spheres). Labels are colored by phenotype. Env side chains interacting with Gag are shown as sticks colored by atom type. Image was created with PyMOL [http://sourceforge.net/projects/pymol/]. The bottom panel shows protein sequence alignments of FFV and PFV Gag and a matrix of. Inter-molecular side-chain interactions indicated with ‘X’. Helical regions identified from the human Gag structure are shown as a black bar; beta strands are shown as a black arrow. Sequence numbers refer to the FFV sequence. The 5-mer mutants and the single point mutants are colored by phenotype as above (GAG_FFV boxes and dots, respectively). Gag residues playing a role in Gag-Env affinity or particle egress [38, 57] are indicated with black dots