第1014回生物科学セミナー
Molecular basis for polyspecificity in the POT family of proton coupled transporters.
Dr. Jo Parker（Department of Biochemistry University of Oxford）
2014年11月26日(水) 13:00-14:00 理学部3号館 327号室
A key characteristic of the proton coupled peptide transporter (POT) family is the mechanism of peptide selectivity, with members being able to recognise and transport over 8000 different peptides. During this talk I will present recent crystal structures of both di- and tri peptide bound complexes of a bacterial peptide transporter, PepTSt.
These structures revealed a multi site-binding mode with di peptide orientated horizontally and tri peptide vertically. I will also discuss the implications of this multi-site binding mode on the mechanism of transport and will show biochemical data indicating that not only are di peptides and tri peptides recognised differently they are also transported by differing mechanisms. With tri-peptides being co transported with three protons and di peptides with four or five.
This unpublished work being the first thermodynamic study of proton:peptide stoichiometry in the POT family and reveals that secondary active transporters can evolve different coupling mechanisms to accommodate and transport chemically and physically diverse ligands across the membrane.
