Fig 5.

Second-site mutations in growth-impaired E89 mutant viruses. Side view (A) and bottom view (B) of a μ1 trimer were rendered using UCSF chimera from the crystal structure of μ1 (PDB entry 1JMU) (10) showing the locations of second-site mutations that are in positions to mediate intratrimer μ1 interactions. Side view (C) and top view (D) of two adjacent μ1 trimers were rendered using UCSF chimera from the crystal and cryoelectron microscopy structures of μ1 (PDB entries 1JMU and 2CSE) (10, 11) showing the locations of second-site mutations that are in positions to mediate intertrimer μ1 interactions. The three monomers within a μ1 trimer are shown as gray-, pink-, and green-colored ribbons. Residue 97 is labeled as residue 89, as the 72-96 loop was not resolved in the crystal structure and is not in the PDB file.