Structural, Bioinformatic, and In Vivo Analyses of Two Treponema pallidum Lipoproteins Reveal a Unique TRAP Transporter

摘要: Treponema pallidum, the bacterial agent of syphilis, is predicted to encode one tripartite ATP-independent periplasmic transporter (TRAP-T). TRAP-Ts typically employ a substrate-binding protein (SBP) deliver cognate ligand transmembrane symporter. Herein, we demonstrate that genes encoding putative TRAP-T components from T. tp0957 (the SBP), and tp0958 symporter), are in an operon with uncharacterized third gene, tp0956. We determined crystal structure recombinant Tp0956; trimeric perforated by pore. Part Tp0956 forms assembly similar those “tetratricopeptide repeat” (TPR) motifs. The Tp0957 was also determined; like SBPs other TRAP-Ts, there two lobes separated cleft. In these SBPs, cleft binds negatively charged ligand. However, has strikingly hydrophobic chemical composition, indicating its may be substantially different likely hydrophobic. Analytical ultracentrifugation versions established proteins associate avidly. This unprecedented interaction confirmed for native molecules using vivo cross-linking experiments. Finally, bioinformatic analyses suggested this exemplifies new subfamily TPATs (TPR-protein-associated TRAP-Ts) require action TPR-containing accessory transport potentially ligand(s).