Ca2+-dependent conformational changes in a C-terminal cytosolic domain of polycystin-2.
The PKD1 and PKD2 genes are the genes that are mutated in patients suffering from autosomal dominant polycystic kidney disease. The human PKD2 gene codes for a 968-amino acid long membrane protein called polycystin-2 that represents a cation channel whose activity can be regulated by Ca(2+) ions. By CD, fluorescence, and NMR spectroscopy, we have studied a 117-amino acid-long fragment of the cytoplasmic domain of polycystin-2, polycystin-2-(680-796) that was proposed to contain a Ca(2+)-binding site. NMR structure determination reveals the existence of two Ca(2+)-binding sites in polycystin-2-(680-796) arranged in a typical and an atypical EF-hand motif. In the absence of Ca(2+) the protein forms a dimer that is dissociated by Ca(2+) binding. This dissociation may be related to the Ca(2+) inactivation observed earlier. The calcium affinity of the protein was determined by fluorescence and NMR spectroscopy. At 293 K, the K(D) values for the high and low affinity sites are 55 mum and 179 mum, respectively.
Schumann
Frank
F
Institute of Biophysics and Physical Biochemistry, University of Regensburg, Regensburg, Germany.
Hoffmeister
Helen
H
Bader
Reto
R
Schmidt
Maren
M
Witzgall
Ralph
R
Kalbitzer
Hans Robert
HR
D020816:Amino Acid Motifs / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D006801:Humans; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D016891:Polycystic Kidney, Autosomal Dominant / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary / Q000235:genetics; D013050:Spectrometry, Fluorescence; D050396:TRPP Cation Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D002118:Calcium; D050396:TRPP Cation Channels