Complex structure of Pseudomonas aeruginosa arginine rhamnosyltransferase EarP with its acceptor elongation factor P.

A bacterial inverting glycosyltransferase EarP transfers rhamnose from dTDP-β-L-rhamnose (TDP-Rha) to Arg32 of translation elongation factor P (EF-P) to activate its function. Here we report structural and biochemical characterization of Pseudomonas aeruginosa EarP. In contrast to recently reported Neisseria meningitidis EarP, P. aeruginosa EarP exhibits differential conformational changes upon TDP-Rha and EF-P binding. Sugar donor binding enhances acceptor binding to EarP as revealed by structural comparison between the apo, TDP-Rha- and TDP/EF-P bound forms and isothermal titration calorimetry experiments. In vitro EF-P rhamnosylation combined with active site geometry indicates that Asp16 corresponding to Asp20 of N. meningitidis EarP is the catalytic base, whereas Glu272 is another putative catalytic residue. Our study should provide the basis for EarP-targeted inhibitor design against infections from P. aeruginosa and other clinically relevant species. IMPORTANCE Post-translational rhamnosylation of EF-P plays a key role in Pseudomonas aeruginosa establishing virulence and antibiotic resistance, as well as survival. The detailed structural and biochemical characterization of the EF-P-specific rhamnosyltransferase EarP from P. aeruginosa not only demonstrates that sugar donor TDP-Rha binding enhances acceptor EF-P binding to EarP but also should provide valuable information for the structure-guided development of its inhibitors against infections from P. aeruginosa and other EarP-containing pathogens.