Mutations in the GUCA1A gene involved in hereditary cone dystrophies impair calcium-mediated regulation of guanylate cyclase.
The GUCA1A gene encodes the guanylate cyclase activating protein 1 (GCAP1) of mammalian rod and cone photoreceptor cells, which is involved in the Ca2+-dependent negative feedback regulation of membrane bound guanylate cyclases in the retina. Mutations in the GUCA1A gene have been associated with different forms of cone dystrophies leading to impaired cone vision and retinal degeneration. Here we report the identification of three novel and one previously detected GUCA1A mutations: c.265G>A (p.Glu89Lys), c.300T>A (p.Asp100Glu), c.476G>T (p.Gly159Val) and c.451C>T (p.Leu151Phe). The clinical data of the patients carrying these mutations were compared with the functional consequences of the mutant GCAP1 forms. For this purpose we purified the heterologously expressed GCAP1 forms and investigated whether the mutations affected the Ca2+-triggered conformational changes and the apparent interaction affinity with the membrane bound guanylate cyclase. Furthermore, we analyzed Ca2+-dependent regulatory modes of wildtype and mutant GCAP1 forms. Although all novel mutants were able to act as a Ca2+-sensor protein, they differed in their Ca2+-dependent activation profiles leading to a persistent stimulation of guanylate cyclase activities at physiological intracellular Ca2+ concentration.
Kitiratschky
Veronique B D
VB
Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University Tübingen, Tübingen, Germany.
Behnen
Petra
P
Kellner
Ulrich
U
Heckenlively
John R
JR
Zrenner
Eberhart
E
Jägle
Herbert
H
Kohl
Susanne
S
Wissinger
Bernd
B
Koch
Karl-Wilhelm
KW
D002118:Calcium / Q000378:metabolism*; D005260:Female; D005838:Genotype; D006162:Guanylate Cyclase / Q000378:metabolism*; D051604:Guanylate Cyclase-Activating Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*; D012162:Retinal Degeneration / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
C496736:GUCA1A protein, human; D051604:Guanylate Cyclase-Activating Proteins; D006162:Guanylate Cyclase; D002118:Calcium