Resolving mechanistic details of peptide transport across membranes using crystallographic and non-crystallographic structural biology approaches

Resumo

Extending our recent new crystallographic structural models, ESR DEER and MD (Fowler et al., (2015) Structure, 23(2):290- 301 - front cover feature), we now aim to define the reaction coordinates for two peptide transporters from the bacteria Shewanella oniedensis (PepTSo) and from Streptococcus thermophilus (PepTSt). Both the conformational changes associated with discernible Intermediates in the transporter pathway(s), as well as the lipid dependence of the various stages are currently not described, and so will be addressed here using underpinning molecular biology approaches in Oxford and Sao Paulo. The response of the transporter to the proton motive force (pmf) in sealed systems, and the nature of the ligand binding environment, will also be examined, giving new Information about direct coupung of peptide transport to the energetics that drives function, with a view to defining electromechanical coupling within this important drug facilitator. To do this we will: - direct the design of spectroscopic studies of membrane-embedded peptide transporters using currently available, as well as new crystal structural and MD generated models; - use the spectroscopic and functional Information to determine conformational and dynamic details of membrane- embedded transporters, and generate novel detailed molecular models of reaction intermediates; With a final goal of describing the mechanism of action, lipid dependence and conformations of reaction intermediate states of peptide (and other homologues) transporters in molecular and kinetic detail. (AU)