Oligomerization of the Polycystin-2 C-terminal Tail and Effects on Its Ca2+-binding Properties*

Autor: Ivana Y. Kuo, Camille Keeler, Barbara E. Ehrlich, Elias Lolis, Michael E. Hodsdon, Yifei Yang
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Models
Molecular
endocrine system
TRPP Cation Channels
Nuclear Magnetic Resonance (NMR)
Molecular Sequence Data
Trimer
Plasma protein binding
Protein aggregation
Biochemistry
Isothermal Titration Calorimetry (ITC)
EF-hand Proteins
Protein Structure
Secondary
Calcium-binding Protein
Transient receptor potential channel
Protein Aggregates
Species Specificity
Polycystic Kidney Disease
Calcium-binding protein
Animals
Humans
Protein Isoforms
Amino Acid Sequence
Binding site
education
Molecular Biology
Ion transporter
education.field_of_study
Binding Sites
Ion Transport
Chemistry
urogenital system
Calcium Intracellular Release
Cell Biology
Recombinant Proteins
Protein Structure
Tertiary
Crystallography
Polycystin 2
Sea Urchins
embryonic structures
Biophysics
Thermodynamics
Calcium
Protein Multimerization
Ion Channel Gating
Sequence Alignment
Molecular Biophysics
Protein Binding
Zdroj: The Journal of Biological Chemistry
ISSN: 1083-351X
0021-9258
Popis: Background: The C-terminal tail of polycystin-2 (PC2 Cterm) is essential for channel assembly and regulation. Results: Both human and sea urchin PC2 Cterm form trimers and contain EF-hand domains that bind to Ca2+. Conclusion: Oligomerization affects Ca2+-binding profiles differently in human and sea urchin PC2. Significance: Characterization of the PC2 Cterm aids the understanding of PC2 channel regulation.
Polycystin-2 (PC2) belongs to the transient receptor potential (TRP) family and forms a Ca2+-regulated channel. The C-terminal cytoplasmic tail of human PC2 (HPC2 Cterm) is important for PC2 channel assembly and regulation. In this study, we characterized the oligomeric states and Ca2+-binding profiles in the C-terminal tail using biophysical approaches. Specifically, we determined that HPC2 Cterm forms a trimer in solution with and without Ca2+ bound, although TRP channels are believed to be tetramers. We found that there is only one Ca2+-binding site in the HPC2 Cterm, located within its EF-hand domain. However, the Ca2+ binding affinity of the HPC2 Cterm trimer is greatly enhanced relative to the intrinsic binding affinity of the isolated EF-hand domain. We also employed the sea urchin PC2 (SUPC2) as a model for biophysical and structural characterization. The sea urchin C-terminal construct (SUPC2 Ccore) also forms trimers in solution, independent of Ca2+ binding. In contrast to the human PC2, the SUPC2 Ccore contains two cooperative Ca2+-binding sites within its EF-hand domain. Consequently, trimerization does not further improve the affinity of Ca2+ binding in the SUPC2 Ccore relative to the isolated EF-hand domain. Using NMR, we localized the Ca2+-binding sites in the SUPC2 Ccore and characterized the conformational changes in its EF-hand domain due to trimer formation. Our study provides a structural basis for understanding the Ca2+-dependent regulation of the PC2 channel by its cytosolic C-terminal domain. The improved methodology also serves as a good strategy to characterize other Ca2+-binding proteins.
Databáze: OpenAIRE
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