Fig. 5.

VtrA periplasmic domain evolution. (A–D) Periplasmic domain SSEs are in rainbow cartoon from the N terminus (blue) to the C terminus (red), with disulfides in black sphere. (A) CadC periplasmic domain has an insertion (magenta) with respect to (B) the VtrA periplasmic domain, with the CadC insertion replaced by an N-terminal extension (slate). (C) Candidate co-component VtrA-like models are colored by the core SSEs in CadC and VtrA. (D) A conserved disulfide (*) links YqeI and TcpP, which includes a C-terminal extension (gray). (E) Representative operon ORFs (labeled by gene) with conserved C-terminal Cys codon (red) overlapping with start codon from input component. (F) Distance matrix of all-against-all structure comparisons colored by distance in red (distant)-white-blue (identical) color scale. Components that interact with confident sequence-related VtrC-like domains are bolded, and their distances are boxed.