FIG. 6.

Conserved cysteines within UL16 are important for UL11 binding. (A) Alignment of regions in UL16 homologs containing six highly conserved cysteine residues. The residue numbers in this region of HSV-1 are indicated. HCMV, human cytomegalovirus; EHV, equine herpesvirus; HHV, human herpesvirus; EBV, Epstein-Barr virus; VZV, varicella-zoster virus. (B) Expression levels of HSV-1 UL16-GFP wild type (WT) and six cysteine-to-serine substitution mutants (C1S to C6S). Codons for the six cysteines indicated in panel A were individually replaced with codons for serine and constructed into the GFP expression vector. The alleles were transfected into A7 cells, and protein expression was examined by immunoblotting for GFP. (C) GST-UL11 pull-down assays. Transfected cells were lysed with detergent and incubated with glutathione bead-bound GST-UL11. Bound proteins were analyzed by SDS-PAGE and immunoblotting for GFP.