NMR and EPR studies of membrane transporters.
In order to fulfill their function, membrane transport proteins have to cycle through a number of conformational and/or energetic states. Thus, understanding the role of conformational dynamics seems to be the key for elucidation of the functional mechanism of these proteins. However, membrane proteins in general are often difficult to express heterologously and in sufficient amounts for structural studies. It is especially challenging to trap a stable energy minimum, e.g., for crystallographic analysis. Furthermore, crystallization is often only possible by subjecting the protein to conditions that do not resemble its native environment and crystals can only be snapshots of selected conformational states. Nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy are complementary methods that offer unique possibilities for studying membrane proteins in their natural membrane environment and for investigating functional conformational changes, lipid interactions, substrate-lipid and substrate-protein interactions, oligomerization states and overall dynamics of membrane transporters. Here, we review recent progress in the field including studies from primary and secondary active transporters.
Hellmich
Ute A
UA
Department of Biophysical Chemistry, Goethe University Frankfurt and Center for Biomolecular Magnetic Resonance, Max von Laue Str. 9, D-60438 Frankfurt/Main, Germany. hellmich@chemie.uni-frankfurt.de
Glaubitz
Clemens
C
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry / Q000378:metabolism; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000378:metabolism*; D017920:Antiporters / Q000737:chemistry / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D002352:Carrier Proteins / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D005971:Glutamates / Q000737:chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D026901:Membrane Transport Proteins / Q000737:chemistry*; D009004:Monosaccharide Transport Proteins / Q000737:chemistry; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D017920:Antiporters; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D005971:Glutamates; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015032:Zinc; C044592:BtuB protein, E coli; C050021:BtuC peptide, E coli; C050022:BtuD peptide, E coli; C101824:LmrA protein, Lactococcus lactis; C461639:MalF protein, E coli; C079123:MalG protein, E coli; C079726:MsbA protein, Bacteria; C017800:zinc-binding protein; C075436:EmrE protein, E coli; C421109:multidrug resistance-associated protein 1