Macromolecular assembly of polycystin-2 intracytosolic C-terminal domain

• Published in: Proceedings of the National Academy of Sciences - PNAS 2011-06, Vol.108 (24), p.9833-9838
• Main Authors: Ferreira, Frederico M., Oliveira, Leandro C., Germino, Gregory G., Onuchic, José N., Onuchic, Luiz F.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Atoms & subatomic particles; Autosomal dominant polycystic kidney; Biological Sciences; Blotting, Western; Calcium; Calcium - chemistry; Calcium - metabolism; Circular Dichroism; Dichroism; Humans; Hydrophobic and Hydrophilic Interactions; Kidney diseases; Modeling; Models, Chemical; Models, Molecular; Molecular Sequence Data; Molecular Weight; Molecules; Monomers; Mutation; Oligomers; Polycystic kidney diseases; Protein Conformation; Protein Multimerization; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Scattering, Small Angle; Simulation; Simulations; Superposition principle; Thermodynamics; TRPP Cation Channels - chemistry; TRPP Cation Channels - genetics; TRPP Cation Channels - metabolism; X-Ray Diffraction
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1106766108

Mutations in PKD2 are responsible for approximately 15% of the autosomal dominant polycystic kidney disease cases. This gene encodes polycystin-2, a calcium-permeable cation channel whose C-terminal intracytosolic tail (PC2t) plays an important role in its interaction with a number of different proteins. In the present study, we have comprehensively evaluated the macromolecular assembly of PC2t homooligomer using a series of biophysical and biochemical analyses. Our studies, based on a new delimitation of PC2t, have revealed that it is capable of assembling as a homotetramer independently of any other portion of the molecule. Our data support this tetrameric arrangement in the presence and absence of calcium. Molecular dynamics simulations performed with a modified all-atoms structure-based model supported the PC2t tetrameric assembly, as well as how different populations are disposed in solution. The simulations demonstrated, indeed, that the best-scored structures are the ones compatible with a fourfold oligomeric state. These findings clarify the structural properties of PC2t domain and strongly support a homotetramer assembly of PC2.