9ym3
Backbone Modification in the Villin Headpiece Miniprotein: HP35 with ACPC at Position 30
Structural highlights
FunctionVILI_CHICK Epithelial cell-specific Ca(2+)-regulated actin-modifying protein that modulates the reorganization of microvillar actin filaments. Plays a role in the actin nucleation, actin filament bundle assembly, actin filament capping and severing. Binds phosphatidylinositol 4,5-bisphosphate (PIP2) and lysophosphatidic acid (LPA); binds LPA with higher affinity than PIP2. Binding to LPA increases its phosphorylation by SRC and inhibits all actin-modifying activities. Binding to PIP2 inhibits actin-capping and -severing activities but enhances actin-bundling activity. Regulates the intestinal epithelial cell morphology, cell invasion, cell migration and apoptosis. Protects against apoptosis induced by dextran sodium sulfate (DSS) in the gastrointestinal epithelium. Appears to regulate cell death by maintaining mitochondrial integrity. Enhances hepatocyte growth factor (HGF)-induced epithelial cell motility, chemotaxis and wound repair (By similarity). Its actin-bundling activity is inhibited by tropomyosin.[1] [2] Publication Abstract from PubMedChanging the backbone connectivity of proteins can impart useful new traits while maintaining essential structural and functional features. In design of artificial proteomimetic agents, backbone modification is usually isolated to sites that are solvent-exposed in the folded state, as similar changes at buried residues can alter the fold. Recent work has shown that core backbone modification without structural perturbation is possible; however, the modifications in that study were consistently destabilizing and made in a prototype of exceptionally high conformational stability. Here, we report efforts to broaden the scope and improve the efficacy of core backbone engineering by applying it to the C-terminal subdomain of villin headpiece. A series of variants are prepared in which different artificial residue types are incorporated at core positions throughout the sequence, including a crucial aromatic triad. Impacts on folding energetics are quantified by biophysical methods, and high-resolution structures of several variants determined by NMR. We go on to construct a variant with approximately 40% of its core modified that adopts a fold identical to the prototype while showing enhanced thermodynamic stability. Backbone engineering in the hydrophobic core of villin headpiece.,Lin Y, David RM, Amin DM, Osborne SWJ, Horne WS RSC Chem Biol. 2025 Dec 17. doi: 10.1039/d5cb00269a. PMID:41450753[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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