High resolution NMR analysis of the seven transmembrane domains of a heptahelical receptor in organic-aqueous medium.
The NMR properties of seven peptides representing the transmembrane domains of the alpha-factor receptor from Saccharomyces cerevisiae were examined in trifluoroethanol/water (4:1) at 10 to 55 degrees C. The parameters extracted indicated all peptides were helical in this membrane mimetic solvent. Using chemical shift indices as the criterion, helicity varied from 64 to 83%. The helical residues in the peptides corresponded to the region predicted to cross the hydrocarbon interior of the bilayer. A study of a truncated 25-residue peptide corresponding to domain 2 gave evidence that the helix extended all the way to the N-terminus of this peptide, indicating that sequence and not chain end effects are very important in helix termination for our model peptides. Both nuclear Overhauser effect spectroscopy (NOESY) connectivities and chemical shift indices revealed significant perturbations around prolyl residues in the helices formed by transmembrane domains 6 and 7. Molecular models of the transmembrane domains indicate that helices for domains 6 and 7 are severely kinked at these prolyl residues. The helix perturbation around proline 258 in transmembrane domain 6 correlates with mutations that cause phenotypic changes in this receptor.
Arshava
Boris
B
Department of Chemistry, The College of Staten Island, Graduate Center of the City University of New York, Staten Island, NY 10314, USA.
Taran
Irina
I
Xie
Haibo
H
Becker
Jeffrey M
JM
Naider
Fred
F
D002462:Cell Membrane / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors; D014867:Water / Q000737:chemistry
D010455:Peptides; D011506:Proteins; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D014157:Transcription Factors; D014867:Water