Genetic and modular structure of TraAB.

(A) Operon structure depicting genes that translationally overlap. (B) Domain and motif architecture and the DK396 amino acid substitution indicated. (C) Modeled three-dimensional structure and electrostatic surface potential of TraA PA14 domain. Features shown in green in the ribbon diagram (left) could serve to recognize glycans through potential side-chain coordination of a calcium ion by Asp183, Asp184, Glu237 (only Cα-Cβ shown), and the location of an insertion important for carbohydrate-binding specificity in FLO5 [24]. Graphics produced with PyMOL (Molecular Graphics System, Version 1.3, Schrödinger, LLC) and APBS Tools2 [61]. (D) consensus sequence LOGO [62] for Cys-repeats found in TraA and myxobacteria family members designated TIGR04201.