Manipulation of ligand binding affinity by exploitation of conformational coupling.
Traditional approaches for increasing the affinity of a protein for its ligand focus on constructing improved surface complementarity in the complex by altering the protein binding site to better fit the ligand. Here we present a novel strategy that leaves the binding site intact, while residues that allosterically affect binding are mutated. This method takes advantage of conformationally distinct states, each with different ligand-binding affinities, and manipulates the equilibria between these conformations. We demonstrate this approach in the Escherichia coli maltose binding protein by introducing mutations, located at some distance from the ligand binding pocket, that sterically affect the equilibrium between an open, apo-state and a closed, ligand-bound state. A family of 20 variants was generated with affinities ranging from an approximately 100-fold improvement (7.4 nM) to an approximately two-fold weakening (1.8 mM) relative to the wild type protein (800 nM).
Marvin
J S
JS
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
Hellinga
H W
HW
D018528:ATP-Binding Cassette Transporters; D000494:Allosteric Regulation; D000495:Allosteric Site; D001059:Apoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002151:Calorimetry; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D007700:Kinetics; D008024:Ligands; D008320:Maltose / Q000378:metabolism*; D058619:Maltose-Binding Proteins; D008958:Models, Molecular; D009004:Monosaccharide Transport Proteins; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011487:Protein Conformation; D015202:Protein Engineering; D013696:Temperature; D013816:Thermodynamics
D018528:ATP-Binding Cassette Transporters; D001059:Apoproteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D008024:Ligands; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; C461599:maltose transport system, E coli; D008320:Maltose