Fig. 7.

Summary of CVSC subunit tagging. Results of successful attempts to localize and orient CVSC subunits by visualizing bulk tags on HSV-1 capsids are combined in this schematic representation. Color coding of subunits is as for Fig. 5 and 6. Previously we labeled UL25 with GFP at amino acid 50 (aa 50) (4), and the location of this residue is indicated with a green cross. We also labeled the N terminus with a TAP tag (gray oval). The locations of these two tags place UL25 in the distal-most region of the CVSC relative to the penton. The tagging data also support fitting of the crystal structure of UL25 (residues 134 to 580) into the middle part of the CVSC (dashed outline). Tagging of UL17 at the C terminus with GFP localizes UL17 to the CVSC, into the penton-proximal domain. A portion of UL17 nearest to the penton may be flexible (indicated by the motion-blurred extension of UL17). Localization of the UL17 and UL25 tags allows us to predict each protein's orientation within the CVSC (as labeled by “N” and “C,” referring to the N- and C-terminal domains, respectively) with confidence for the C terminus of UL17 and N terminus of UL25 and by inference vice versa. The UL17 and UL25 proteins appear likely to be organized in a C-terminal-to-C-terminal manner.