An indole-binding site is a major determinant of the ligand specificity of the GABA type A receptor-associated protein GABARAP.
The role of tryptophan as a key residue for ligand binding to the ubiquitin-like modifier GABA(A) receptor associated protein (GABARAP) was investigated. Two tryptophan-binding hydrophobic patches were identified on the conserved face of the GABARAP structure by NMR spectroscopy and molecular docking. GABARAP binding of indole and indole derivatives, including the free amino acid tryptophan was quantified. The two tryptophan binding sites can be clearly distinguished by mapping the NMR spectroscopy-derived residue-specific apparent dissociation constant, K(d), onto the three-dimensional structure of GABARAP. The biological relevance of tryptophan-binding pockets of GABARAP was supported by a highly conserved tryptophan residue in the GABARAP binding region of calreticulin, clathrin heavy chain, and the gamma2 subunit of the GABA(A) receptor. Replacement of tryptophan by alanine abolished ligand binding to GABARAP.
INB-2/Molekulare Biophysik II, Forschungszentrum Jülich, 52425 Jülich, Germany.
Yvonne
Y
Thielmann
Jeannine
J
Mohrlüder
Bernd W
BW
Koenig
Thomas
T
Stangler
Rudolf
R
Hartmann
Karin
K
Becker
Hans-Dieter
HD
Höltje
Dieter
D
Willbold
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011963:Receptors, GABA-A / Q000378:metabolism*; D013379:Substrate Specificity; D017186:Titrimetry; D014364:Tryptophan / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D007211:Indoles; D008024:Ligands; D008869:Microtubule-Associated Proteins; D011963:Receptors, GABA-A; D014364:Tryptophan