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Qureshi BM, Schmidt A, Behrmann E, Bürger J, Mielke T, Spahn CMT, Heck M, Scheerer P. Mechanistic insights into the role of prenyl-binding protein PrBP/δ in membrane dissociation of phosphodiesterase 6. Nat Commun 2018; 9:90. [PMID: 29311697 PMCID: PMC5758567 DOI: 10.1038/s41467-017-02569-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 12/11/2017] [Indexed: 01/01/2023] Open
Abstract
Isoprenylated proteins are associated with membranes and their inter-compartmental distribution is regulated by solubilization factors, which incorporate lipid moieties in hydrophobic cavities and thereby facilitate free diffusion during trafficking. Here we report the crystal structure of a solubilization factor, the prenyl-binding protein (PrBP/δ), at 1.81 Å resolution in its ligand-free apo-form. Apo-PrBP/δ harbors a preshaped, deep hydrophobic cavity, capacitating apo-PrBP/δ to readily bind its prenylated cargo. To investigate the molecular mechanism of cargo solubilization we analyzed the PrBP/δ-induced membrane dissociation of rod photoreceptor phosphodiesterase (PDE6). The results suggest that PrBP/δ exclusively interacts with the soluble fraction of PDE6. Depletion of soluble species in turn leads to dissociation of membrane-bound PDE6, as both are in equilibrium. This “solubilization by depletion” mechanism of PrBP/δ differs from the extraction of prenylated proteins by the similar folded solubilization factor RhoGDI, which interacts with membrane bound cargo via an N-terminal structural element lacking in PrBP/δ. The prenyl-binding protein PrBP/δ is a solubilization factor involved in trafficking of prenylated proteins. Here the authors present the ligand-free apo-PrBP/δ structure and propose a "solubilization by depletion" mechanism, where PrBP/δ sequesters only soluble rod photoreceptor phosphodiesterase (PDE6), leading to a dissociation of membrane-bound PDE6.
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Affiliation(s)
- Bilal M Qureshi
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Cryo Electron Microscopy, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Enzyme Kinetics, Charitéplatz 1, D-10117, Berlin, Germany.,Division of Biological & Environmental Sciences & Engineering, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia
| | - Andrea Schmidt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, D-10117, Berlin, Germany
| | - Elmar Behrmann
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Cryo Electron Microscopy, Charitéplatz 1, D-10117, Berlin, Germany.,Research Group Structural Dynamics of Proteins, Center of Advanced European Studies and Research (Caesar), Ludwig-Erhard-Allee 2, D-53175, Bonn, Germany.,Institute of Biochemistry-Structural Biochemistry, University of Cologne, Zuelpicher Straße 47, D-50674, Cologne, Germany
| | - Jörg Bürger
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Cryo Electron Microscopy, Charitéplatz 1, D-10117, Berlin, Germany.,UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195, Berlin, Germany
| | - Thorsten Mielke
- UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195, Berlin, Germany
| | - Christian M T Spahn
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Cryo Electron Microscopy, Charitéplatz 1, D-10117, Berlin, Germany
| | - Martin Heck
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Enzyme Kinetics, Charitéplatz 1, D-10117, Berlin, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, D-10117, Berlin, Germany. .,Charité - Universitätsmedizin Berlin, Institut für Medizinische Physik und Biophysik (CC2), Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, D-10117, Berlin, Germany.
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Yamazaki A, Hayashi F, Matsuura I, Bondarenko VA. Binding of cGMP to the transducin-activated cGMP phosphodiesterase, PDE6, initiates a large conformational change involved in its deactivation. FEBS J 2011; 278:1854-72. [PMID: 21439020 DOI: 10.1111/j.1742-4658.2011.08104.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Retinal photoreceptor phosphodiesterase (PDE6), a key enzyme for phototransduction, consists of a catalytic subunit complex (Pαβ) and two inhibitory subunits (Pγs). Pαβ has two noncatalytic cGMP-binding sites. Here, using bovine PDE preparations, we show the role of these cGMP-binding sites in PDE regulation. Pαβγγ and its transducin-activated form, Pαβγ, contain two and one cGMP, respectively. Only Pαβγ shows [(3)H]cGMP binding with a K(d) ∼ 50 nM and Pγ inhibits the [(3)H]cGMP binding. Binding of cGMP to Pαβγ is suppressed during its formation, implying that cGMP binding is not involved in Pαβγγ activation. Once bound to Pαβγ, [(3)H]cGMP is not dissociated even in the presence of a 1000-fold excess of unlabeled cGMP, binding of cGMP changes the apparent Stokes' radius of Pαβγ, and the amount of [(3)H]cGMP-bound Pαβγ trapped by a filter is spontaneously increased during its incubation. These results suggest that Pαβγ slowly changes its conformation after cGMP binding, i.e. after formation of Pαβγ containing two cGMPs. Binding of Pγ greatly shortens the time to detect the increase in the filter-trapped level of [(3)H]cGMP-bound Pαβγ, but alters neither the level nor its Stokes' radius. These results suggest that Pγ accelerates the conformational change, but does not add another change. These observations are consistent with the view that Pαβγ changes its conformation during its deactivation and that the binding of cGMP and Pγ is crucial for this change. These observations also imply that Pαβγγ changes its conformation during its activation and that release of Pγ and cGMP is essential for this change.
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Affiliation(s)
- Akio Yamazaki
- Kresge Eye Institute, Wayne State University, Detroit, MI, USA
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Yamazaki A, Bondarenko VA, Matsuura I, Tatsumi M, Kurono S, Komori N, Matsumoto H, Hayashi F, Yamazaki RK, Usukura J. Mechanism for the regulation of mammalian cGMP phosphodiesterase6. 1: identification of its inhibitory subunit complexes and their roles. Mol Cell Biochem 2010; 339:215-33. [PMID: 20151179 DOI: 10.1007/s11010-010-0387-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 01/25/2010] [Indexed: 10/19/2022]
Abstract
Cyclic GMP phosphodiesterase (PDE) in bovine rod photoreceptor outer segments (OS) comprises a catalytic subunit complex (Palphabeta) and two inhibitory subunits (Pgamma) and is regulated by the alpha subunit of transducin (Talpha). Here, we show an overall mechanism for PDE regulation by identifying Pgamma complexes in OS homogenates prepared with an isotonic buffer. Before Talpha activation, three Pgamma complexes exist in the soluble fraction. Complex a, a minor complex, contains Palphabeta, Talpha, and a protein named Pdelta. Complex b, Palphabetagammagamma( b ), has a PDE activity similar to that of membranous Palphabetagammagamma, Palphabetagammagamma( M ), and its level, although its large portion is Pdelta-free, is estimated to be 20-30% of the total Palphabetagammagamma. Complex c, (Pgamma.GDP-Talpha) (2) ( c ) , appears to be a dimer of Pgamma.GDP-Talpha. Upon Talpha activation, (1) complex a stays unchanged, (2) Palphabetagammagamma( b ) binds to membranes, (3) the level of (Pgamma.GDP-Talpha) (2) ( c ) is reduced as its GTP-form is produced, (4) complex d, Pgamma.GTP-Talpha( d ), is formed on membranes and its substantial amount is released to the soluble fraction, and (5) membranous Palphabetagammagamma, Palphabetagammagamma( M ) and/or Palphabetagammagamma( b ), becomes Pgamma-depleted. These observations indicate that Pgamma as a complex with GTP-Talpha dissociates from Palphabetagammagamma on membranes and is released to the soluble fraction and that Pgamma-depleted PDE is the GTP-Talpha-activated PDE. After GTP hydrolysis, both (Pgamma.GDP-Talpha) (2) ( c ) and Pgamma.GDP-Talpha( d ), without liberating Pgamma, deactivate Pgamma-depleted PDE. The preferential order to be used for the deactivation is membranous Pgamma.GDP-Talpha( d ), solubilized Pgamma.GDP-Talpha( d ) and (Pgamma.GDP-Talpha) (2) ( c ) . Release of Pgamma.GTP-Talpha complexes to the soluble fraction is relevant to light adaptation.
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Affiliation(s)
- Akio Yamazaki
- Department of Ophthalmology, Kresge Eye Institute, Wayne State University, 4717 St. Antoine St., Detroit, MI 48201-1423, USA.
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