Ordered self-assembly mechanism of a spherical oncoprotein oligomer triggered by zinc removal and stabilized by an intrinsically disordered domain
Background: Self-assembly is a common theme in proteins of unrelated sequences or functions. The human papillomavirus E7 oncoprotein is an extended dimer with an intrinsically disordered domain, that can form large spherical oligomers. These are the major species in the cytosol of HPV transformed an...
| Authors: | , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2012 |
| Country: | Argentina |
| Institution: | Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales |
| Repository: | Biblioteca Digital (UBA-FCEN) |
| Language: | English |
| OAI Identifier: | paperaa:paper_19326203_v7_n5_p_Smal |
| Online Access: | http://hdl.handle.net/20.500.12110/paper_19326203_v7_n5_p_Smal |
| Access Level: | Open access |
| Keyword: | amyloid precursor protein amyloid protein chaperone oligomer protein E7 zinc oncogene protein E7, Human papillomavirus type 16 amino terminal sequence article carboxy terminal sequence circular dichroism concentration (parameters) drug research immunogenicity kinetics nanotechnology oligomerization protein assembly protein binding protein conformation protein domain protein polymerization protein quaternary structure protein secondary structure protein stability protein tertiary structure Wart virus chemistry genetics human Human papillomavirus type 16 metabolism protein multimerization Human papillomavirus Human papillomavirus 16 Humans Papillomavirus E7 Proteins Protein Multimerization Protein Stability Protein Structure, Quaternary Protein Structure, Tertiary Zinc |
| Summary: | Background: Self-assembly is a common theme in proteins of unrelated sequences or functions. The human papillomavirus E7 oncoprotein is an extended dimer with an intrinsically disordered domain, that can form large spherical oligomers. These are the major species in the cytosol of HPV transformed and cancerous cells. E7 binds to a large number of targets, some of which lead to cell transformation. Thus, the assembly process not only is of biological relevance, but represents a model system to investigate a widely distributed mechanism. Methodology/Principal Findings: Using various techniques, we monitored changes in secondary, tertiary and quaternary structure in a time course manner. By applying a robust kinetic model developed by Zlotnik, we determined the slow formation of a monomeric "Z-nucleus" after zinc removal, followed by an elongation phase consisting of sequential second-order events whereby one monomer is added at a time. This elongation process takes place at a strikingly slow overall average rate of one monomer added every 28 seconds at 20 μM protein concentration, strongly suggesting either a rearrangement of the growing complex after binding of each monomer or the existence of a "conformation editing" mechanism through which the monomer binds and releases until the appropriate conformation is adopted. The oligomerization determinant lies within its small 5 kDa C-terminal globular domain and, remarkably, the E7 N-terminal intrinsically disordered domain stabilizes the oligomer, preventing an insoluble amyloid route. Conclusion: We described a controlled ordered mechanism with features in common with soluble amyloid precursors, chaperones, and other spherical oligomers, thus sharing determining factors for symmetry, size and shape. In addition, such a controlled and discrete polymerization reaction provides a valuable tool for nanotechnological applications. Finally, its increased immunogenicity related to its supramolecular structure is the basis for the development of a promising therapeutic vaccine candidate for treating HPV cancerous lesions. © 2012 Smal et al. |
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