Biophysical Basis of the Binding of WWOX Tumor Suppressor to WBP1 and WBP2 Adaptors

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• 作者：Caleb B. McDonald ; Laura Buffa ; Tomer Bar-Mag ; Zaidoun Salah ; Vikas Bhat ; David C. Mikles ; Brian J. Deegan ; Kenneth L. Seldeen ; Arun Malhotra ; Marius Sudol ; Rami I. Aqeilan ; Zafar Nawaz ; Amjad Farooq
• 关键词：DSC ; differential scanning calorimetry ; GST ; glutathione S-transferase ; ITC ; isothermal titration calorimetry ; MD ; molecular dynamics ; PPII ; polyproline type II ; WBP1 ; WW-binding protein 1 ; WBP2 ; WW-binding protein 2 ; WWOX ; WW-containing oxidoreductase ; R
• 刊名：Journal of Molecular Biology
• 出版年：2012
• 出版时间：7 September, 2012
• 年：2012
• 卷：422
• 期：1
• 页码：58-74
• 全文大小：1699 K

文摘

The WW-containing oxidoreductase (WWOX) tumor suppressor participates in a diverse array of cellular activities by virtue of its ability to recognize WW-binding protein 1 (WBP1) and WW-binding protein 2 (WBP2) signaling adaptors among a wide variety of other ligands. Herein, using a multitude of biophysical techniques, we provide evidence that while the WW1 domain of WWOX binds to PPXY motifs within WBP1 and WBP2 in a physiologically relevant manner, the WW2 domain exhibits no affinity toward any of these PPXY motifs. Importantly, our data suggest that while R25/W44 residues located within the binding pocket of a triple-stranded ¦Â-fold of WW1 domain are critical for the recognition of PPXY ligands, they are replaced by the chemically distinct E66/Y85 duo at structurally equivalent positions within the WW2 domain, thereby accounting for its failure to bind PPXY ligands. Predictably, not only does the introduction of E66R/Y85W double substitution within the WW2 domain result in gain of function but the resulting engineered domain, hereinafter referred to as WW2_RW, also appears to be a much stronger binding partner of WBP1 and WBP2 than the wild-type WW1 domain. We also show that while the WW1 domain is structurally disordered and folds upon ligand binding, the WW2 domain not only adopts a fully structured conformation but also aids stabilization and ligand binding to WW1 domain. This salient observation implies that the WW2 domain likely serves as a chaperone to augment the physiological function of WW1 domain within WWOX. Collectively, our study lays the groundwork for understanding the molecular basis of a key protein-protein interaction pertinent to human health and disease.