7 research outputs found
Rigidified Clicked Dimeric Ligands for Studying the Dynamics of the PDZ1-2 Supramodule of PSD-95
From the Selective Serotonin Transporter Inhibitor Citalopram to the Selective Norepinephrine Transporter Inhibitor Talopram: Synthesis and StructureâActivity Relationship Studies
Cell-Permeable and Plasma-Stable Peptidomimetic Inhibitors of the Postsynaptic Density-95/ N
Probing the Role of Backbone Hydrogen Bonds in ProteinâPeptide Interactions by Amide-to-Ester Mutations
One of the most frequent
proteinâprotein interaction modules
in mammalian cells is the postsynaptic density 95/discs large/zonula
occludens 1 (PDZ) domain, involved in scaffolding and signaling and
emerging as an important drug target for several diseases. Like many
other proteinâprotein interactions, those of the PDZ domain
family involve formation of intermolecular hydrogen bonds: C-termini
or internal linear motifs of proteins bind as β-strands to form
an extended antiparallel β-sheet with the PDZ domain. Whereas
extensive work has focused on the importance of the amino acid side
chains of the protein ligand, the role of the backbone hydrogen bonds
in the binding reaction is not known. Using amide-to-ester substitutions
to perturb the backbone hydrogen-bonding pattern, we have systematically
probed putative backbone hydrogen bonds between four different PDZ
domains and peptides corresponding to natural protein ligands. Amide-to-ester
mutations of the three C-terminal amides of the peptide ligand severely
affected the affinity with the PDZ domain, demonstrating that hydrogen
bonds contribute significantly to ligand binding (apparent changes
in binding energy, ÎÎ<i>G</i> = 1.3 to >3.8
kcal mol<sup>â1</sup>). This decrease in affinity was mainly
due to an increase in the dissociation rate constant, but a significant
decrease in the association rate constant was found for some amide-to-ester
mutations suggesting that native hydrogen bonds have begun to form
in the transition state of the binding reaction. This study provides
a general framework for studying the role of backbone hydrogen bonds
in proteinâpeptide interactions and for the first time specifically
addresses these for PDZ domainâpeptide interactions
Probing the Role of Backbone Hydrogen Bonds in Protein-Peptide Interactions by Amide-to-Ester Mutations
One of the most frequent protein-protein interaction modules in mammalian cells is the postsynaptic density 95/discs large/zonula occludens 1 (PDZ) domain, involved in scaffolding and signaling and emerging as an important drug target for several diseases. Like many other protein-protein interactions, those of the PDZ domain family involve formation of intermolecular hydrogen bonds: C-termini or internal linear motifs of proteins bind as beta-strands to form an extended antiparallel beta-sheet with the PDZ domain. Whereas extensive work has focused on the importance of the, amino acid side chains of the protein ligand, the role of the backbone hydrogen bonds in the binding reaction is not known. Using amide-to-ester substitutions to perturb the backbone hydrogen-bonding pattern, we have systematically probed putative backbone hydrogen bonds between four different PDZ domains and peptides corresponding to natural protein ligands. Amide-to-ester mutations of the three C-terminal amides of the peptide ligand severely affected the affinity with the PDZ domain, demonstrating that hydrogen bonds contribute significantly to ligand binding (apparent changes in binding energy, Delta Delta G = 1.3 to >3.8 kcal mol(-1)). This decrease in affinity was mainly due to an increase in the dissociation rate constant, but a significant decrease in the association rate constant was found for some amide-to-ester mutations Suggesting that native hydrogen bonds have begun to form in the transition state of the binding reaction. This study provides a general framework for studying the role of backbone hydrogen bonds in protein-peptide interactions and for the first time specifically addresses these for PDZ domain-peptide interactions