FIG. 8.

Sequence alignment of a portion of the VirA periplasmic domain and the ligand recognition domain of Trg, showing the presence of an identical 4-XXXXX-4 amino acid motif with two regions of identity (depicted in gray and underlined). This motif in Trg is thought to be the ligand interaction site for ribose binding protein and has been the site of extensive study (7, 58, 74). VirA amino acids that were the mutagenized for this study are boxed, with substitutions at these sites shown beneath them.