1
|
Biasi A, Marino V, Dal Cortivo G, Dell'Orco D. Supramolecular complexes of GCAP1: implications for inherited retinal dystrophies. Int J Biol Macromol 2024; 279:135068. [PMID: 39187109 DOI: 10.1016/j.ijbiomac.2024.135068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 08/16/2024] [Accepted: 08/23/2024] [Indexed: 08/28/2024]
Abstract
Guanylate Cyclase Activating Protein 1 (GCAP1) is a calcium sensor that regulates the enzymatic activity of retinal Guanylate Cyclase 1 (GC1) in photoreceptors in a Ca2+/Mg2+ dependent manner. While point mutations in GCAP1 have been associated with inherited retinal dystrophies (IRDs), their impact on protein dimerization or on the possible interaction with the potent GC1 inhibitor RD3 (retinal degeneration protein 3) has never been investigated. Here, we integrate exhaustive in silico investigations with biochemical assays to evaluate the effects of the p.(E111V) substitution, associated with a severe form of IRD, on GCAP1 homo- and hetero-dimerization, and demonstrate that wild type (WT) GCAP1 directly interacts with RD3. Although inducing constitutive activation in GC1, the E111V substitution only slightly affects the dimerization of GCAP1. Both WT- and E111V-GCAP1 are predominantly monomeric in the absence of the GC1 target, however E111V-GCAP1 shows a stronger tendency to be monomeric in the Ca2+-bound form, corresponding to GC1 inhibiting state. Reconstitution experiments performed in the co-presence of WT-GCAP1, E111V-GCAP1 and RD3 restored nearly physiological regulation of the GC1 enzymatic activity in terms of cGMP synthesis and Ca2+-sensitivity, suggesting new scenarios for biologics-mediated treatment of GCAP1-associated IRDs.
Collapse
Affiliation(s)
- Amedeo Biasi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.
| |
Collapse
|
2
|
Marino V, Cortivo GD, Dell'Orco D. Ionic displacement of Ca 2+ by Pb 2+ in calmodulin is affected by arrhythmia-associated mutations. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119490. [PMID: 37201768 DOI: 10.1016/j.bbamcr.2023.119490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/14/2023] [Accepted: 05/10/2023] [Indexed: 05/20/2023]
Abstract
Lead is a highly toxic metal that severely perturbs physiological processes even at sub-micromolar levels, often by disrupting the Ca2+ signaling pathways. Recently, Pb2+-associated cardiac toxicity has emerged, with potential involvement of both the ubiquitous Ca2+ sensor protein calmodulin (CaM) and ryanodine receptors. In this work, we explored the hypothesis that Pb2+ contributes to the pathological phenotype of CaM variants associated with congenital arrhythmias. We performed a thorough spectroscopic and computational characterization of CaM conformational switches in the co-presence of Pb2+ and four missense mutations associated with congenital arrhythmias, namely N53I, N97S, E104A and F141L, and analyzed their effects on the recognition of a target peptide of RyR2. When bound to any of the CaM variants, Pb2+ is difficult to displace even under equimolar Ca2+ concentrations, thus locking all CaM variants in a specific conformation, which exhibits characteristics of coiled-coil assemblies. All arrhythmia-associated variants appear to be more susceptible to Pb2+ than WT CaM, as the conformational transition towards the coiled-coil conformation occurs at lower Pb2+, regardless of the presence of Ca2+, with altered cooperativity. The presence of arrhythmia-associated mutations specifically alters the cation coordination of CaM variants, in some cases involving allosteric communication between the EF-hands in the two domains. Finally, while wild type CaM increases the affinity for the RyR2 target in the presence of Pb2+, no specific pattern could be detected for all other variants, ruling out a synergistic effect of Pb2+ and mutations in the recognition process.
Collapse
Affiliation(s)
- Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy.
| |
Collapse
|
3
|
Avesani A, Bielefeld L, Weisschuh N, Marino V, Mazzola P, Stingl K, Haack TB, Koch KW, Dell’Orco D. Molecular Properties of Human Guanylate Cyclase-Activating Protein 3 (GCAP3) and Its Possible Association with Retinitis Pigmentosa. Int J Mol Sci 2022; 23:ijms23063240. [PMID: 35328663 PMCID: PMC8948881 DOI: 10.3390/ijms23063240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/12/2022] [Accepted: 03/15/2022] [Indexed: 11/17/2022] Open
Abstract
The cone-specific guanylate cyclase-activating protein 3 (GCAP3), encoded by the GUCA1C gene, has been shown to regulate the enzymatic activity of membrane-bound guanylate cyclases (GCs) in bovine and teleost fish photoreceptors, to an extent comparable to that of the paralog protein GCAP1. To date, the molecular mechanisms underlying GCAP3 function remain largely unexplored. In this work, we report a thorough characterization of the biochemical and biophysical properties of human GCAP3, moreover, we identified an isolated case of retinitis pigmentosa, in which a patient carried the c.301G>C mutation in GUCA1C, resulting in the substitution of a highly conserved aspartate residue by a histidine (p.(D101H)). We found that myristoylated GCAP3 can activate GC1 with a similar Ca2+-dependent profile, but significantly less efficiently than GCAP1. The non-myristoylated form did not induce appreciable regulation of GC1, nor did the p.D101H variant. GCAP3 forms dimers under physiological conditions, but at odds with its paralogs, it tends to form temperature-dependent aggregates driven by hydrophobic interactions. The peculiar properties of GCAP3 were confirmed by 2 ms molecular dynamics simulations, which for the p.D101H variant highlighted a very high structural flexibility and a clear tendency to lose the binding of a Ca2+ ion to EF3. Overall, our data show that GCAP3 has unusual biochemical properties, which make the protein significantly different from GCAP1 and GCAP2. Moreover, the newly identified point mutation resulting in a substantially unfunctional protein could trigger retinitis pigmentosa through a currently unknown mechanism.
Collapse
Affiliation(s)
- Anna Avesani
- Section of Biological Chemistry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37134 Verona, Italy; (A.A.); (V.M.)
| | - Laura Bielefeld
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26111 Oldenburg, Germany; (L.B.); (K.-W.K.)
| | - Nicole Weisschuh
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, 72076 Tübingen, Germany;
| | - Valerio Marino
- Section of Biological Chemistry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37134 Verona, Italy; (A.A.); (V.M.)
| | - Pascale Mazzola
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany; (P.M.); (T.B.H.)
| | - Katarina Stingl
- University Eye Hospital, Centre for Ophthalmology, University of Tübingen, 72076 Tübingen, Germany;
| | - Tobias B. Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany; (P.M.); (T.B.H.)
- Centre for Rare Diseases, University of Tübingen, 72076 Tübingen, Germany
| | - Karl-Wilhelm Koch
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26111 Oldenburg, Germany; (L.B.); (K.-W.K.)
| | - Daniele Dell’Orco
- Section of Biological Chemistry, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37134 Verona, Italy; (A.A.); (V.M.)
- Correspondence: ; Tel.: +39-045-802-7637
| |
Collapse
|
4
|
Parys JB, Bultynck G. Preface to the Special Issue of the European Calcium Society in honor of Professor Sir Michael J. Berridge. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119172. [PMID: 34774604 DOI: 10.1016/j.bbamcr.2021.119172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, BE-3000 Leuven, Belgium.
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, BE-3000 Leuven, Belgium.
| |
Collapse
|
5
|
Biasi A, Marino V, Dal Cortivo G, Maltese PE, Modarelli AM, Bertelli M, Colombo L, Dell’Orco D. A Novel GUCA1A Variant Associated with Cone Dystrophy Alters cGMP Signaling in Photoreceptors by Strongly Interacting with and Hyperactivating Retinal Guanylate Cyclase. Int J Mol Sci 2021; 22:ijms221910809. [PMID: 34639157 PMCID: PMC8509414 DOI: 10.3390/ijms221910809] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 11/19/2022] Open
Abstract
Guanylate cyclase-activating protein 1 (GCAP1), encoded by the GUCA1A gene, is a neuronal calcium sensor protein involved in shaping the photoresponse kinetics in cones and rods. GCAP1 accelerates or slows the cGMP synthesis operated by retinal guanylate cyclase (GC) based on the light-dependent levels of intracellular Ca2+, thereby ensuring a timely regulation of the phototransduction cascade. We found a novel variant of GUCA1A in a patient affected by autosomal dominant cone dystrophy (adCOD), leading to the Asn104His (N104H) amino acid substitution at the protein level. While biochemical analysis of the recombinant protein showed impaired Ca2+ sensitivity of the variant, structural properties investigated by circular dichroism and limited proteolysis excluded major structural rearrangements induced by the mutation. Analytical gel filtration profiles and dynamic light scattering were compatible with a dimeric protein both in the presence of Mg2+ alone and Mg2+ and Ca2+. Enzymatic assays showed that N104H-GCAP1 strongly interacts with the GC, with an affinity that doubles that of the WT. The doubled IC50 value of the novel variant (520 nM for N104H vs. 260 nM for the WT) is compatible with a constitutive activity of GC at physiological levels of Ca2+. The structural region at the interface with the GC may acquire enhanced flexibility under high Ca2+ conditions, as suggested by 2 μs molecular dynamics simulations. The altered interaction with GC would cause hyper-activity of the enzyme at both low and high Ca2+ levels, which would ultimately lead to toxic accumulation of cGMP and Ca2+ in the photoreceptor outer segment, thus triggering cell death.
Collapse
Affiliation(s)
- Amedeo Biasi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy; (A.B.); (V.M.); (G.D.C.)
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy; (A.B.); (V.M.); (G.D.C.)
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy; (A.B.); (V.M.); (G.D.C.)
| | | | - Antonio Mattia Modarelli
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, 20142 Milano, Italy;
| | - Matteo Bertelli
- MAGI’S Lab s.r.l., 38068 Rovereto, Italy; (P.E.M.); (M.B.)
- MAGI Euregio, 39100 Bolzano, Italy
| | - Leonardo Colombo
- Department of Ophthalmology, ASST Santi Paolo e Carlo Hospital, University of Milan, 20142 Milano, Italy;
- Correspondence: (L.C.); (D.D.); Tel.: +39-02-81844301 (L.C.); +39-045-802-7637 (D.D.)
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy; (A.B.); (V.M.); (G.D.C.)
- Correspondence: (L.C.); (D.D.); Tel.: +39-02-81844301 (L.C.); +39-045-802-7637 (D.D.)
| |
Collapse
|
6
|
Structural Insights into Retinal Guanylate Cyclase Activator Proteins (GCAPs). Int J Mol Sci 2021; 22:ijms22168731. [PMID: 34445435 PMCID: PMC8395740 DOI: 10.3390/ijms22168731] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/16/2022] Open
Abstract
Retinal guanylate cyclases (RetGCs) promote the Ca2+-dependent synthesis of cGMP that coordinates the recovery phase of visual phototransduction in retinal rods and cones. The Ca2+-sensitive activation of RetGCs is controlled by a family of photoreceptor Ca2+ binding proteins known as guanylate cyclase activator proteins (GCAPs). The Mg2+-bound/Ca2+-free GCAPs bind to RetGCs and activate cGMP synthesis (cyclase activity) at low cytosolic Ca2+ levels in light-activated photoreceptors. By contrast, Ca2+-bound GCAPs bind to RetGCs and inactivate cyclase activity at high cytosolic Ca2+ levels found in dark-adapted photoreceptors. Mutations in both RetGCs and GCAPs that disrupt the Ca2+-dependent cyclase activity are genetically linked to various retinal diseases known as cone-rod dystrophies. In this review, I will provide an overview of the known atomic-level structures of various GCAP proteins to understand how protein dimerization and Ca2+-dependent conformational changes in GCAPs control the cyclase activity of RetGCs. This review will also summarize recent structural studies on a GCAP homolog from zebrafish (GCAP5) that binds to Fe2+ and may serve as a Fe2+ sensor in photoreceptors. The GCAP structures reveal an exposed hydrophobic surface that controls both GCAP1 dimerization and RetGC binding. This exposed site could be targeted by therapeutics designed to inhibit the GCAP1 disease mutants, which may serve to mitigate the onset of retinal cone-rod dystrophies.
Collapse
|
7
|
Marino V, Dal Cortivo G, Maltese PE, Placidi G, De Siena E, Falsini B, Bertelli M, Dell’Orco D. Impaired Ca 2+ Sensitivity of a Novel GCAP1 Variant Causes Cone Dystrophy and Leads to Abnormal Synaptic Transmission Between Photoreceptors and Bipolar Cells. Int J Mol Sci 2021; 22:ijms22084030. [PMID: 33919796 PMCID: PMC8070792 DOI: 10.3390/ijms22084030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 01/23/2023] Open
Abstract
Guanylate cyclase-activating protein 1 (GCAP1) is involved in the shutdown of the phototransduction cascade by regulating the enzymatic activity of retinal guanylate cyclase via a Ca2+/cGMP negative feedback. While the phototransduction-associated role of GCAP1 in the photoreceptor outer segment is widely established, its implication in synaptic transmission to downstream neurons remains to be clarified. Here, we present clinical and biochemical data on a novel isolate GCAP1 variant leading to a double amino acid substitution (p.N104K and p.G105R) and associated with cone dystrophy (COD) with an unusual phenotype. Severe alterations of the electroretinogram were observed under both scotopic and photopic conditions, with a negative pattern and abnormally attenuated b-wave component. The biochemical and biophysical analysis of the heterologously expressed N104K-G105R variant corroborated by molecular dynamics simulations highlighted a severely compromised Ca2+-sensitivity, accompanied by minor structural and stability alterations. Such differences reflected on the dysregulation of both guanylate cyclase isoforms (RetGC1 and RetGC2), resulting in the constitutive activation of both enzymes at physiological levels of Ca2+. As observed with other GCAP1-associated COD, perturbation of the homeostasis of Ca2+ and cGMP may lead to the toxic accumulation of second messengers, ultimately triggering cell death. However, the abnormal electroretinogram recorded in this patient also suggested that the dysregulation of the GCAP1–cyclase complex further propagates to the synaptic terminal, thereby altering the ON-pathway related to the b-wave generation. In conclusion, the pathological phenotype may rise from a combination of second messengers’ accumulation and dysfunctional synaptic communication with bipolar cells, whose molecular mechanisms remain to be clarified.
Collapse
Affiliation(s)
- Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37129 Verona, Italy; (V.M.); (G.D.C.)
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37129 Verona, Italy; (V.M.); (G.D.C.)
| | | | - Giorgio Placidi
- Fondazione Policlinico Universitario “A. Gemelli”, IRCCS, 00168 Rome, Italy; (G.P.); (E.D.S.)
- Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Elisa De Siena
- Fondazione Policlinico Universitario “A. Gemelli”, IRCCS, 00168 Rome, Italy; (G.P.); (E.D.S.)
- Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Benedetto Falsini
- Fondazione Policlinico Universitario “A. Gemelli”, IRCCS, 00168 Rome, Italy; (G.P.); (E.D.S.)
- Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Correspondence: (B.F.); (D.D.); Tel.: +39-06-3015-6344 (B.F.); +39-045-802-7637 (D.D.)
| | - Matteo Bertelli
- MAGI’S Lab S.R.L., 38068 Rovereto, Italy; (P.E.M.); (M.B.)
- MAGI Euregio, 39100 Bolzano, Italy
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37129 Verona, Italy; (V.M.); (G.D.C.)
- Correspondence: (B.F.); (D.D.); Tel.: +39-06-3015-6344 (B.F.); +39-045-802-7637 (D.D.)
| |
Collapse
|