Targeting the SH3 domain of human osteoclast ‐stimulating factor with rationally designed peptoid inhibitors

Human osteoclast‐stimulating factor (hOSF) is an intracellular protein produced by osteoclasts that induces osteoclast formation and bone resorption. The protein contains a modular Src homology 3 (SH3) domain that mediates the intermolecular recognition and interaction of hOSF with its biological partners. Here, we proposed targeting the hOSF SH3 domain to disrupt hOSF–partner interactions for bone disease therapy by using SH3 inhibitors. In the procedure, the primary sequences of three known hOSF‐interacting proteins (c‐Src, SMN and Sam68) were parsed, from which totally 31 octapeptide segments that contain the core SH3‐binding motif PXXP were extracted, and their binding behavior to hOSF SH3 domain was investigated at structural level using a biomolecular modeling protocol. Several SH3‐binding candidates were identified theoretically and then determined to have high or moderate affinity for the domain using fluorescence spectroscopy assays. One potent peptide 425APPARPVK432 (Kd = 3.2 μM), which corresponds to the residues 425–432 of Sam68 protein, was used as template to derive N substitution of peptides (peptoids). Considering that proline is the only endogenous N‐substituted amino acid that plays a critical role in SH3–peptide binding, the substitution was addressed at the two key proline residues (Pro427 and Pro430) of the template peptide with nine N‐substituted amino acid types. By systematically evaluating the structural and energetic effect...
Source: Journal of Peptide Science - Category: Biochemistry Authors: Tags: Research Article Source Type: research