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Bernier SC, Millette MA, Roy S, Cantin L, Coutinho A, Salesse C. Structural information and membrane binding of truncated RGS9-1 Anchor Protein and its C-terminal hydrophobic segment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183566. [PMID: 33453187 DOI: 10.1016/j.bbamem.2021.183566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/22/2020] [Accepted: 01/10/2021] [Indexed: 01/19/2023]
Abstract
Visual phototransduction takes place in photoreceptor cells. Light absorption by rhodopsin leads to the activation of transducin as a result of the exchange of its GDP for GTP. The GTP-bound ⍺-subunit of transducin then activates phosphodiesterase (PDE), which in turn hydrolyzes cGMP leading to photoreceptor hyperpolarization. Photoreceptors return to the dark state upon inactivation of these proteins. In particular, PDE is inactivated by the protein complex R9AP/RGS9-1/Gβ5. R9AP (RGS9-1 anchor protein) is responsible for the membrane anchoring of this protein complex to photoreceptor outer segment disk membranes most likely by the combined involvement of its C-terminal hydrophobic domain as well as other types of interactions. This study thus aimed to gather information on the structure and membrane binding of the C-terminal hydrophobic segment of R9AP as well as of truncated R9AP (without its C-terminal domain, R9AP∆TM). Circular dichroism and infrared spectroscopic measurements revealed that the secondary structure of R9AP∆TM mainly includes ⍺-helical structural elements. Moreover, intrinsic fluorescence measurements of native R9AP∆TM and individual mutants lacking one tryptophan demonstrated that W79 is more buried than W173 but that they are both located in a hydrophobic environment. This method also revealed that membrane binding of R9AP∆TM does not involve regions near its tryptophan residues, while infrared spectroscopy validated its binding to lipid vesicles. Additional fluorescence measurements showed that the C-terminal segment of R9AP is membrane embedded. Maximum insertion pressure and synergy data using Langmuir monolayers suggest that interactions with specific phospholipids could be involved in the membrane binding of R9AP∆TM.
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Affiliation(s)
- Sarah C Bernier
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Marc-Antoine Millette
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sarah Roy
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Ana Coutinho
- iBB-Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Department of Chemistry and Biochemistry, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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Comparison between the enzymatic activity, structure and substrate binding of mouse and human lecithin retinol acyltransferase. Biochem Biophys Res Commun 2019; 519:832-837. [PMID: 31561851 DOI: 10.1016/j.bbrc.2019.09.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 09/15/2019] [Indexed: 11/22/2022]
Abstract
Lecithin retinol acyltransferase (LRAT) is involved in the visual cycle where it catalyzes the formation of all-trans retinyl ester. The mouse animal model has been widely used to study LRAT. Primary sequence alignment shows 80% identity and 90% similarity between human and mouse LRAT. However, human LRAT has a proline at position 173 (hLRAT (P173)) while an arginine can be found at this position for the mouse protein (mLRAT (R173)). Moreover, residue 173 is important for the human protein since a substitution mutation of this residue to a leucine (P173L-hLRAT) caused night blindness in a patient. The present study was thus undertaken to determine whether mouse and human LRAT have a similar enzymatic activity, structure and substrate binding affinity using a truncated form of LRAT (tLRAT). The enzymatic activity and binding affinity to the substrate, all-trans retinol, of mtLRAT (R173) were found to be 2.7- and 3.9-fold lower, respectively, than that of htLRAT (P173). Moreover, the enzymatic activity of P173L-htLRAT is 6.3-fold lower compared to that of htLRAT (P173). Furthermore, a significant difference was observed between the intrinsic fluorescence emission as well as between the circular dichroism spectra of mtLRAT (R173) and htLRAT (P173). In addition, mtLRAT proteins are less thermostable than htLRAT proteins, which suggests that structural differences exist between the mouse and human proteins. Altogether, these data strongly suggest that the much lower catalytic activity of mtLRAT (R173) compared to that of htLRAT (P173) mostly results from differences between their structure, predominantly revealed by their dissimilar thermal stability, as well as their efficiency to bind all-trans retinol. Therefore, conclusions regarding the behavior of human LRAT based on measurements performed with mouse LRAT must be made with caution. Also, the much lower enzymatic activity of P173L-htLRAT compared to that of htLRAT (P173) might explain the night blindness of a patient carrying this mutation.
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Bernier SC, Cantin L, Salesse C. Systematic analysis of the expression, solubility and purification of a passenger protein in fusion with different tags. Protein Expr Purif 2018; 152:92-106. [DOI: 10.1016/j.pep.2018.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 07/13/2018] [Accepted: 07/19/2018] [Indexed: 12/31/2022]
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Novotná P, Urbanová M. A Solid Phase Vibrational Circular Dichroism Study of Polypeptide-Surfactant Interaction. Chirality 2015; 27:965-72. [DOI: 10.1002/chir.22534] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 08/07/2015] [Accepted: 08/27/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Pavlína Novotná
- Department of Analytical Chemistry; University of Chemistry and Technology; Prague Czech Republic
| | - Marie Urbanová
- Department of Physics and Measurements; University of Chemistry and Technology; Prague Czech Republic
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Souza AL, Pavinatto FJ, Caseli L, Volpati D, Miranda PB, Oliveira Jr. ON. Chitosan does not inhibit enzymatic action of human pancreatic lipase in Langmuir monolayers of 1,2-didecanoyl-glycerol (DDG). Colloids Surf B Biointerfaces 2014; 123:870-7. [DOI: 10.1016/j.colsurfb.2014.10.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 10/13/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
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Horchani H, Bussières S, Cantin L, Lhor M, Laliberté-Gemme JS, Breton R, Salesse C. Enzymatic activity of Lecithin:retinol acyltransferase: a thermostable and highly active enzyme with a likely mode of interfacial activation. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1844:1128-36. [PMID: 24613493 PMCID: PMC4469483 DOI: 10.1016/j.bbapap.2014.02.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 01/28/2023]
Abstract
Lecithin:retinol acyltransferase (LRAT) plays a major role in the vertebrate visual cycle. Indeed, it is responsible for the esterification of all-trans retinol into all-trans retinyl esters, which can then be stored in microsomes or further metabolized to produce the chromophore of rhodopsin. In the present study, a detailed characterization of the enzymatic properties of truncated LRAT (tLRAT) has been achieved using in vitro assay conditions. A much larger tLRAT activity has been obtained compared to previous reports and to an enzyme with a similar activity. In addition, tLRAT is able to hydrolyze phospholipids bearing different chain lengths with a preference for micellar aggregated substrates. It therefore presents an interfacial activation property, which is typical of classical phospholipases. Furthermore, given that stability is a very important quality of an enzyme, the influence of different parameters on the activity and stability of tLRAT has thus been studied in detail. For example, storage buffer has a strong effect on tLRAT activity and high enzyme stability has been observed at room temperature. The thermostability of tLRAT has also been investigated using circular dichroism and infrared spectroscopy. A decrease in the activity of tLRAT was observed beyond 70°C, accompanied by a modification of its secondary structure, i.e. a decrease of its α-helical content and the appearance of unordered structures and aggregated β-sheets. Nevertheless, residual activity could still be observed after heating tLRAT up to 100°C. The results of this study highly improved our understanding of this enzyme.
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Affiliation(s)
- Habib Horchani
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sylvain Bussières
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Mustapha Lhor
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Jean-Sébastien Laliberté-Gemme
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Rock Breton
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de Recherche du CHU de Québec, Québec, Québec, Canada; Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada; Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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Novotná P, Urbanová M. Vibrational circular dichroism study of polypeptide model–membrane systems. Anal Biochem 2012; 427:211-8. [DOI: 10.1016/j.ab.2012.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/25/2012] [Accepted: 03/26/2012] [Indexed: 12/01/2022]
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Golczak M, Kiser PD, Sears AE, Lodowski DT, Blaner WS, Palczewski K. Structural basis for the acyltransferase activity of lecithin:retinol acyltransferase-like proteins. J Biol Chem 2012; 287:23790-807. [PMID: 22605381 DOI: 10.1074/jbc.m112.361550] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lecithin:retinol acyltransferase-like proteins, also referred to as HRAS-like tumor suppressors, comprise a vertebrate subfamily of papain-like or NlpC/P60 thiol proteases that function as phospholipid-metabolizing enzymes. HRAS-like tumor suppressor 3, a representative member of this group, plays a key role in regulating triglyceride accumulation and energy expenditure in adipocytes and therefore constitutes a novel pharmacological target for treatment of metabolic disorders causing obesity. Here, we delineate a catalytic mechanism common to lecithin:retinol acyltransferase-like proteins and provide evidence for their alternative robust lipid-dependent acyltransferase enzymatic activity. We also determined high resolution crystal structures of HRAS-like tumor suppressor 2 and 3 to gain insight into their active site architecture. Based on this structural analysis, two conformational states of the catalytic Cys-113 were identified that differ in reactivity and thus could define the catalytic properties of these two proteins. Finally, these structures provide a model for the topology of these enzymes and allow identification of the protein-lipid bilayer interface. This study contributes to the enzymatic and structural understanding of HRAS-like tumor suppressor enzymes.
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Affiliation(s)
- Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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Bussières S, Cantin L, Desbat B, Salesse C. Binding of a truncated form of lecithin:retinol acyltransferase and its N- and C-terminal peptides to lipid monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:3516-3523. [PMID: 22260449 DOI: 10.1021/la203896n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lecithin:retinol acyltransferase (LRAT) is a 230 amino acid membrane-associated protein which catalyzes the esterification of all-trans-retinol into all-trans-retinyl ester. A truncated form of LRAT (tLRAT), which contains the residues required for catalysis but which is lacking the N- and C-terminal hydrophobic segments, was produced to study its membrane binding properties. Measurements of the maximum insertion pressure of tLRAT, which is higher than the estimated lateral pressure of membranes, and the positive synergy factor a argue in favor of a strong binding of tLRAT to phospholipid monolayers. Moreover, the binding, secondary structure and orientation of the peptides corresponding to its N- and C-terminal hydrophobic segments of LRAT have been studied by circular dichroism and polarization-modulation infrared reflection absorption spectroscopy in monolayers. The results show that these peptides spontaneously bind to lipid monolayers and adopt an α-helical secondary structure. On the basis of these data, a new membrane topology model of LRAT is proposed where its N- and C-terminal segments allow to anchor this protein to the lipid bilayer.
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Affiliation(s)
- Sylvain Bussières
- LOEX/CUO-recherche, Centre hospitalier affilié universitaire de Québec, Hôpital du Saint-Sacrement, 1050 Chemin Ste-Foy, Québec (Québec), Canada
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Bussières S, Cantin L, Salesse C. Lecithin retinol acyltransferase and its S175R mutant have a similar secondary structure content and maximum insertion pressure but different enzyme activities. Exp Eye Res 2011; 93:778-81. [DOI: 10.1016/j.exer.2011.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 07/18/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
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Lakhani A, Malon P, Keiderling TA. Comparison of vibrational circular dichroism instruments: development of a new dispersive VCD. APPLIED SPECTROSCOPY 2009; 63:775-785. [PMID: 19589215 DOI: 10.1366/000370209788701189] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A dispersive vibrational circular dichroism (VCD) instrument has been designed and optimized for the measurement of mid-infrared (MIR) bands such as the amide I and amide II vibrational modes of peptides and proteins. The major design considerations were to construct a compact VCD instrument for biological molecules, to increase signal-to-noise (S/N) ratio, to simultaneously collect and digitize the sample transmission and polarization modulation signals, and to digitally ratio them to yield a VCD spectrum. These were realized by assembling new components using design factors adapted from previous VCD instruments. A collection of spectra for peptides and proteins having different dominant secondary structures (alpha-helix, beta-sheet, and random coil) measured for identical samples under the same conditions showed that the new instrument had substantially improved S/N as compared with our previous dispersive VCD instrument. These instruments both provide protein VCD for the amide I that are comparable to or somewhat better than those measurable with commercial Fourier transform (FT) VCD instruments if just the amide I band in the spectra is obtained at modest resolution (8 cm(-1)) with the same total data collection time on each type of instrument.
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Affiliation(s)
- Ahmed Lakhani
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street (m/c 111), Chicago, Illinois 60607-7061, USA
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