TY - JOUR
T1 - Mapping of ligand binding sites of the cholecystokinin-B/gastrin receptor with lipo-gastrin peptides and molecular modeling
AU - Lutz, Jürgen
AU - Romano-Götsch, Roberta
AU - Escrieut, Chantal
AU - Fourmy, Daniel
AU - Mathä, Barbara
AU - Müller, Gerhard
AU - Kassler, Horst
AU - Moroder, Luis
PY - 1997
Y1 - 1997
N2 - Double-tailed lipo-tetragastrin derivatives of increasing fatty acid chain length were used to identify the minimum size of the fatty acid moieties (≥C10) that restricts the access to the CCK-B/gastrin (CCK: cholecystokinin) receptor via a membrane-bound pathway. Then dimyristoyl-mercaptoglycerol/maleoyl-gastrin adducts of increasing peptide chain length were synthesized to define the minimal peptide size required for receptor binding affinities comparable to those of underivatized gastrin peptides despite anchorage of the lipid tails in the membrane bilayer. The experimental results indicated that most of the little-gastrin sequence, i.e., 2-17, is needed for optimal interaction of the molecule with the binding cleft of the receptor. From these data experimentally based restraints could be derived for docking of lipo-gastrin onto a CCK-B/gastrin receptor model applying molecular dynamics simulations and energy minimizations. In the receptor-bound state some of the secondary structure elements of gastrin as determined by nmr analysis of gastrin-peptides in low dielectric constant media are retained. The N-terminal gastrin portion interacts in a more or less extended conformation with the receptor surface, and upon a sharp kink at the Ala-Tyr dipeptide portion the C-terminal pentapeptide amide part inserts deeply into the helix bundle. Besides Arg-57 on top of helix 1 of the receptor, for which no potential interaction with the ligand could be detected, the other amino acid residues identified by mutagenesis studies as involved in gastrin recognition were found to interact with the C-terminal portion of gastrin. Even taking into account the strong limitations of such a model system, it represents an interesting tool for rationalizing the experimental results of the extensive structure-function studies performed previously on gastrin and to delineate more precisely the putative ligand binding site on the extracellular face of the receptor.
AB - Double-tailed lipo-tetragastrin derivatives of increasing fatty acid chain length were used to identify the minimum size of the fatty acid moieties (≥C10) that restricts the access to the CCK-B/gastrin (CCK: cholecystokinin) receptor via a membrane-bound pathway. Then dimyristoyl-mercaptoglycerol/maleoyl-gastrin adducts of increasing peptide chain length were synthesized to define the minimal peptide size required for receptor binding affinities comparable to those of underivatized gastrin peptides despite anchorage of the lipid tails in the membrane bilayer. The experimental results indicated that most of the little-gastrin sequence, i.e., 2-17, is needed for optimal interaction of the molecule with the binding cleft of the receptor. From these data experimentally based restraints could be derived for docking of lipo-gastrin onto a CCK-B/gastrin receptor model applying molecular dynamics simulations and energy minimizations. In the receptor-bound state some of the secondary structure elements of gastrin as determined by nmr analysis of gastrin-peptides in low dielectric constant media are retained. The N-terminal gastrin portion interacts in a more or less extended conformation with the receptor surface, and upon a sharp kink at the Ala-Tyr dipeptide portion the C-terminal pentapeptide amide part inserts deeply into the helix bundle. Besides Arg-57 on top of helix 1 of the receptor, for which no potential interaction with the ligand could be detected, the other amino acid residues identified by mutagenesis studies as involved in gastrin recognition were found to interact with the C-terminal portion of gastrin. Even taking into account the strong limitations of such a model system, it represents an interesting tool for rationalizing the experimental results of the extensive structure-function studies performed previously on gastrin and to delineate more precisely the putative ligand binding site on the extracellular face of the receptor.
KW - Cholecystokinin-B/gastrin receptor
KW - Gastrin
KW - Ligand binding sites
KW - Lipo-gastrin derivatives
KW - Molecular modeling
UR - http://www.scopus.com/inward/record.url?scp=0031172055&partnerID=8YFLogxK
U2 - 10.1002/(SICI)1097-0282(199706)41:7<799::AID-BIP8>3.0.CO;2-K
DO - 10.1002/(SICI)1097-0282(199706)41:7<799::AID-BIP8>3.0.CO;2-K
M3 - Article
C2 - 9128441
AN - SCOPUS:0031172055
SN - 0006-3525
VL - 41
SP - 799
EP - 817
JO - Biopolymers
JF - Biopolymers
IS - 7
ER -