A vibrational spectroscopic investigation of interactions of agonists with GluR0, a prokaryotic glutamate receptor.
We have used Fourier transform infrared spectroscopy to provide a detailed picture of the interactions between the carboxylate groups of the ligands, glutamate, serine, and glutamine, with the ligand-binding domain of a prokaryotic ionotropic glutamate receptor (GluR0). The vibrational spectra indicate that the noncovalent interactions between the 1C(alpha)-carboxylate moiety of the ligand and the protein are stronger for glutamate than for serine and glutamine. These results correlate well with the higher affinity of glutamate for GluR0-S1S2 relative to the affinities of serine and glutamine. In addition, all three ligands induce similar changes in the vibrational spectra and intrinsic fluorescence of the protein, which indicates that all three ligands induce the same structural changes in the protein. These results are consistent with the recent crystal structures of the glutamate and serine bound forms of GluR0-S1S2 and in addition provide insights into the structure of the glutamine bound form of the protein.
Cheng
Qing
Q
Chemistry Department, Marquette University, Milwaukee, Wisconsin 53233, USA.
Thiran
Shalita
S
Yernool
Dinesh
D
Gouaux
Eric
E
Jayaraman
Vasanthi
V
D001426:Bacterial Proteins; D002264:Carboxylic Acids / Q000737:chemistry; D000458:Cyanobacteria / Q000737:chemistry; D017666:Deuterium Oxide / Q000737:chemistry; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006860:Hydrogen Bonding; D008024:Ligands; D015221:Potassium Channels / Q000819:agonists* / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017470:Receptors, Glutamate / Q000737:chemistry* / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D055672:Static Electricity; D014732:Vibration
D001426:Bacterial Proteins; D002264:Carboxylic Acids; D008024:Ligands; D015221:Potassium Channels; D017470:Receptors, Glutamate; D005973:Glutamine; D018698:Glutamic Acid; D012694:Serine; D017666:Deuterium Oxide