Title
Refining the Dynamic Network of T2SS Endopilus Tip Hetero-Complex Combining Cw-EPR and Nitroxide-Gd(III) Distance Measurements
Author
Gerbaud, Guillaume, Brice Barbat, Mathilde Tribout, Emilien Etienne, Valerie Belle, Badreddine Douzi, Romé Voulhoux, and Alessio Bonucci
Year
2023
Journal
ChemBioChem
Abstract
The type 2 secretion system (T2SS) is a bacterial nanomachine constituted by an inner membrane assembly platform, an outer membrane pore and a dynamic endopilus. T2SS endopili are organized into a homo-multimeric body formed by the major pilin capped by a hetero-complex of four minor pilins. The first model of the T2SS endopilus was recently released even if structural dynamics insights are still required to decipher the role of each protein in the full tetrameric complex. Here, we applied continuous wave and pulse EPR spectroscopy using nitroxide-gadolinium orthogonal labelling strategies to investigate the hetero-oligomeric assembly of the minor pilins. Overall, our data are in line with the endopilus model even if they evidenced conformational flexibility and alternative orientations at local scale of specific regions of minor pilins. The integration of different labelling strategies and EPR experiments demonstrates the pertinence of this approach to investigate protein-protein interactions in such multi protein hetero-complexes.
Instrument
J-815
Keywords
The type 2 secretion system (T2SS)