Structural role of the conserved cysteines in the dimerization of the viral transmembrane oncoprotein E5
| Autor: | Soraya Benamira, Sergii Afonin, Silke Hoffmann, Birgid Langer, Dirk Windisch, Claudia Muhle-Goll, Jochen Bürck, Stefanie Vollmer, Anne S. Ulrich |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular Circular dichroism Magnetic Resonance Spectroscopy Amino Acid Motifs Molecular Sequence Data Biophysics Conserved sequence Cell membrane medicine Amino Acid Sequence Cysteine Disulfides Lipid bilayer Protein Structure Quaternary Peptide sequence Protein secondary structure Conserved Sequence Bovine papillomavirus 1 Chemistry Circular Dichroism Cell Membrane Temperature Membrane Oncogene Proteins Viral Hydrogen-Ion Concentration Transmembrane protein Transmembrane domain medicine.anatomical_structure Biochemistry Mutation Mutagenesis Site-Directed Protein Multimerization |
| Zdroj: | Biophysical journal. 99(6) |
| ISSN: | 1542-0086 |
| Popis: | The E5 oncoprotein is the major transforming protein of bovine papillomavirus type 1. This 44-residue transmembrane protein can interact with the platelet-derived growth factor receptor β, leading to ligand-independent activation and cell transformation. For productive interaction, E5 needs to dimerize via a C-terminal pair of cysteines, though a recent study suggested that its truncated transmembrane segment can dimerize on its own. To analyze the structure of the full protein in a membrane environment and elucidate the role of the Cys-Ser-Cys motif, we produced recombinantly the wild-type protein and four cysteine mutants. Comparison by circular dichroism in detergent micelles and lipid vesicular dispersion and by NMR in trifluoroethanol demonstrates that the absence of one or both cysteines does not influence the highly α-helical secondary structure, nor does it impair the ability of E5 to dimerize, observations that are further supported by sodium dodecylsulfate polyacrylamide gel electrophoresis. We also observed assemblies of higher order. Oriented circular dichroism in lipid bilayers shows that E5 is aligned as a transmembrane helix with a slight tilt angle, and that this membrane alignment is also independent of any cysteines. We conclude that the Cys-containing motif represents a disordered region of the protein that serves as an extra covalent connection for stabilization. |
| Databáze: | OpenAIRE |
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