Nile, A. H. | bioRxiv Science

bioRxiv2023

Discovery of reactive peptide inhibitors of human papillomavirus oncoprotein E6

Human papillomavirus (HPV) infections account for nearly all cervical cancer cases, which is the fourth most common cancer in women worldwide. High-risk variants, including HPV16, drive tumorigenesis in part by promoting the degradation of the tumor suppressor p53. This degradation is mediated by the HPV early protein 6 (E6), which recruits the E3 ubiquitin ligase E6AP and redirects its activity towards ubiquitinating p53. Targeting the protein interaction interface between HPV E6 and E6AP is a promising modality to mitigate HPV-mediated degradation of p53. In this study, we designed a covalent peptide inhibitor, termed reactide, that mimics the E6AP LXXLL binding motif by selectively targeting cysteine 58 in HPV16 E6 with quantitative conversion. This reactide provides a starting point in the development of covalent peptidomimetic inhibitors for intervention against HPV-driven cancers.

molecular biology↗

bioRxiv2022

Mechanisms by Which Small Molecule Inhibitors Arrest Sec14 Phosphatidylinositol Transfer Protein Activity

Phosphatidylinositol transfer proteins (PITPs) promote phosphoinositide signaling by enhancing phosphatidylinositol (PtdIns) 4-OH kinase activities in producing signaling pools of PtdIns-4-phosphate. As such, PITPs are key regulators of lipid signaling in eukaryotic cells. While the PITP phospholipid exchange cycle is the engine that stimulates PtdIns 4-OH kinase activity, the protein and lipid dynamics associated with this critical process are not understood. Herein, we use an integrative structural approach that takes advantage of small molecule inhibitors (SMIs) directed against the major yeast PITP (Sec14) to gain new insights into the mechanics of the Sec14 phospholipid exchange cycle from the perspective of protein, phospholipid and SMI dynamics. Moreover, as Sec14 has emerged as an attractive target for next-generation antifungal drugs, the structures of Sec14 bound to SMIs of four different chemotypes reported in this study provide critical information required for structure-based design of next-generation lead compounds that target Sec14 PITPs of virulent fungi.

biophysics↗