Site-directed solid-state NMR measurement of a ligand-induced conformational change in the serine bacterial chemoreceptor.
The challenging nature of studies of membrane proteins has made it difficult to determine the molecular mechanism of transmembrane signaling. For the bacterial chemoreceptor family, there are crystal structures of the internal and external domains, structural models of the transmembrane domain, and evidence for subtle ligand-induced conformational changes, but the signaling mechanism remains controversial. We have used a novel site-directed solid-state NMR distance measurement approach, using (13)C(19)F REDOR, to measure a ligand-induced change of 1.0 +/- 0.3 A in the distance between helices alpha 1 and alpha 4 of the ligand-binding domain in the intact, membrane-bound serine receptor. This distance change is shown not to be due to motion of the side chain and thus is due to motion of either the alpha 1 or the alpha 4 helix. Additional distance measurements can be used to determine the type of backbone motion and to follow it to the cytoplasm, to test and refine current proposals for the mechanism of transmembrane signaling. This is a promising general method for high-resolution measurements of local structure in intact, membrane-bound proteins.
Murphy
O J
OJ
Graduate Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003-4510, USA.
Kovacs
F A
FA
Sicard
E L
EL
Thompson
L K
LK
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002247:Carbon Isotopes; D002633:Chemotaxis / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli / Q000502:physiology; D005461:Fluorine; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D012694:Serine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D002247:Carbon Isotopes; D008024:Ligands; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; C057635:Tsr protein, Bacteria; D005461:Fluorine; D012694:Serine