Fig. 1.

Genetic organization of the pIP501 tra operon. Proteins with sequence similarities to the corresponding A. tumefaciens Ti-plasmid VirB/D4, E. faecalis pCF10 and C. perfringens pCW3 T4SS proteins are colored in blue; the potential two-protein fusion coupling protein (consisting of TraI_pIP501 and TraJ_pIP501) is indicated with brackets; relations based on structure (TraM C-terminal domain – VirB8-like Goessweiner-Mohr et al., 2013) and domain prediction (TraL – VirB6-like) based similarities are marked in yellow; the gene encoding the putative relaxase is colored in red. Ptra, tra operon promoter. The bent arrow with the (-) indicates the TraA-mediated regulation of the expression of all proteins encoded in the tra_pIP501 operon. The genes of the pIP501 tra operon are drawn to scale.