Identification and Specificity Studies of Small-Molecule Ligands for SH3 Protein Domains

Abstract

The Src Homology 3 (SH3) domains are small protein-protein interaction domains that bind proline-rich sequences and mediate a wide range of cell-signaling and other important biological processes. Since deregulated signaling pathways form the basis of many human diseases, the SH3 domains have been attractive targets for novel therapeutics. High-affinity ligands for SH3 domains have been designed; however, these have all been peptide-based and no examples of entirely nonpeptide SH3 ligands have previously been reported. Using the mouse Tec Kinase SH3 domain as a model system for structure-based ligand design, we have identified several simple heterocyclic compounds that selectively bind to the Tec SH3 domain. Using a combination of nuclear magnetic resonance chemical shift perturbation, structure-activity relationships, and site-directed mutagenesis, the binding of these compounds at the proline-rich peptide-binding site has been characterized. The most potent of these, 2-aminoquinoline, bound with Kd = 125 microM and was able to compete for binding with a proline-rich peptide. Synthesis of 6-substituted-2-aminoquinolines resulted in ligands with up to 6-fold improved affinity over 2-aminoquinoline and enhanced specificity for the Tec SH3 domain. Therefore, 2-aminoquinolines may potentially be useful for the development of high affinity small molecule ligands for SH3 domains.

Enteropathogenic Escherichia coli Tir is an SH2/3 ligand that recruits and activates tyrosine kinases required for pedestal formation

“…Our results also suggest that the SH3–polyproline interaction might prove to be an important therapeutic target. Recent reports demonstrated the design of non‐natural N‐substituted amino acids incorporated into polyproline‐like peptide structures (Nguyen et al ., 1998), and that small non‐peptide molecule mimics of SH3 ligands bind efficiently to the Tec SH3 domain (Inglis et al ., 2004). Such molecules may competitively interfere with SH3–polyproline binding and could be developed into therapeutics.…”

Copper‐Catalyzed Direct Transformation of Secondary Allylic and Benzylic Alcohols into Azides and Amides: An Efficient Utility of Azide as a Nitrogen Source

“…( E )‐ N ,3‐Bis(4‐methoxyphenyl)acrylamide (2b): 39 White solid (79.3 mg, 56 % yield); R f = 0.4 (25 % EtOAc/hexane). IR (KBr): $\tilde {\nu}$ = 3275, 2841, 1653, 1616, 1604, 1507, 1300, 1243, 1168, 1029, 1004, 823 cm –1 .…”

How Much Binding Affinity Can be Gained by Filling a Cavity?

“…The role of halogen substitutions has been extensively discussed in the literature. Different authors have found that K d or IC 50 values improve up to a point in which a further increase in van der Waals radius brings a significant decrease in affinity (4–13). The breaking point occurs at different van der Waals radii (i.e.…”