Membrane transporters studied by EPR spectroscopy: structure determination and elucidation of functional dynamics.
During their mechanistic cycles membrane transporters often undergo extensive conformational changes, sampling a range of orientations, in order to complete their function. Such membrane transporters present somewhat of a challenge to conventional structural studies; indeed, crystallization of membrane-associated proteins sometimes require conditions that vary vastly from their native environments. Moreover, this technique currently only allows for visualization of single selected conformations during any one experiment. EPR spectroscopy is a magnetic resonance technique that offers a unique opportunity to study structural, environmental and dynamic properties of such proteins in their native membrane environments, as well as readily sampling their substrate-binding-induced dynamic conformational changes especially through complementary computational analyses. Here we present a review of recent studies that utilize a variety of EPR techniques in order to investigate both the structure and dynamics of a range of membrane transporters and associated proteins, focusing on both primary (ABC-type transporters) and secondary active transporters which were key interest areas of the late Professor Stephen Baldwin to whom this review is dedicated.
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Anna
A
Mullen
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Jenny
J
Hall
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Janika
J
Diegel
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Isa
I
Hassan
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K.
Adam
A
Fey
Henry Wellcome Unit for Biological EPR, School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K. Fraser.MacMillan@uea.ac.uk.
Fraser
F
MacMillan
D000818:Animals; D001419:Bacteria / Q000378:metabolism; D001692:Biological Transport; D004578:Electron Spin Resonance Spectroscopy; D056890:Eukaryota / Q000378:metabolism; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008968:Molecular Conformation
D026901:Membrane Transport Proteins
ABC proteins; EPR spectroscopy; membrane transport; protein dynamics; spin labelling