Calcium binding, structural stability and guanylate cyclase activation in GCAP1 variants associated with human cone dystrophy

Guanylate cyclase activating protein 1 (GCAP1) is a neuronal Ca2+ sensor (NCS) that regulates the activation of rod outer segment guanylate cyclases (ROS-GCs) in photoreceptors. In this study, we investigated the Ca2+-induced effects on the conformation and the thermal stability of four GCAP1 variants associated with hereditary human cone dystrophies. Ca2+ binding stabilized the conformation of all the GCAP1 variants independent of myristoylation. The myristoylated wild-type GCAP1 was found to have the highest Ca2+ affinity and thermal stability, whereas all the mutants showed decreased Ca2+ affinity and significantly lower thermal stability in both apo and Ca2+-loaded forms. No apparent cooperativity of Ca2+ binding was detected for any variant. Finally, the nonmyristoylated mutants were still capable of activating ROS-GC1, but the measured cyclase activity was shifted toward high, nonphysiological Ca2+ concentrations. Thus, we conclude that distorted Ca2+-sensor properties could lead to cone dysfunction.

Behnen, Petra (författare)
Linse, SaraLund University,Lunds universitet,Biokemi och Strukturbiologi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biochemistry and Structural Biology,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)fkm2-sli (författare)
Koch, Karl-Wilhelm (författare)
Biokemi och StrukturbiologiCentrum för Molekylär Proteinvetenskap (creator_code:org_t)

Ingår i:Cellular and Molecular Life Sciences: Springer Science and Business Media LLC67:6, s. 973-9841420-90711420-682X

Av författaren/redakt...: Dell'Orco, Danie ...; Behnen, Petra; Linse, Sara; Koch, Karl-Wilhe ...

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