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Abiko LA, Rogowski M, Gautier A, Schertler G, Grzesiek S. Efficient production of a functional G protein-coupled receptor in E. coli for structural studies. JOURNAL OF BIOMOLECULAR NMR 2021; 75:25-38. [PMID: 33501610 PMCID: PMC7897205 DOI: 10.1007/s10858-020-00354-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/08/2020] [Indexed: 05/22/2023]
Abstract
G protein-coupled receptors (GPCRs) are transmembrane signal transducers which regulate many key physiological process. Since their discovery, their analysis has been limited by difficulties in obtaining sufficient amounts of the receptors in high-quality, functional form from heterologous expression hosts. Albeit highly attractive because of its simplicity and the ease of isotope labeling for NMR studies, heterologous expression of functional GPCRs in E. coli has proven particularly challenging due to the absence of the more evolved protein expression and folding machinery of higher eukaryotic hosts. Here we first give an overview on the previous strategies for GPCR E. coli expression and then describe the development of an optimized robust protocol for the E. coli expression and purification of two mutants of the turkey β1-adrenergic receptor (β1AR) uniformly or selectively labeled in 15N or 2H,15N. These mutants had been previously optimized for thermal stability using insect cell expression and used successfully in crystallographic and NMR studies. The same sequences were then used for E. coli expression. Optimization of E. coli expression was achieved by a quantitative analysis of losses of receptor material at each step of the solubilization and purification procedure. Final yields are 0.2-0.3 mg receptor per liter culture. Whereas both expressed mutants are well folded and competent for orthosteric ligand binding, the less stable YY-β1AR mutant also comprises the two native tyrosines Y5.58 and Y7.53, which enable G protein binding. High-quality 1H-15N TROSY spectra were obtained for E. coli-expressed YY-β1AR in three different functional states (antagonist, agonist, and agonist + G protein-mimicking nanobody-bound), which are identical to spectra obtained of the same forms of the receptor expressed in insect cells. NdeI and AgeI restriction sites introduced into the expression plasmid allow for the easy replacement of the receptor gene by other GPCR genes of interest, and the provided quantitative workflow analysis may guide the respective adaptation of the purification protocol.
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Affiliation(s)
- Layara Akemi Abiko
- Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, 4056, Basel, Switzerland.
| | - Marco Rogowski
- Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, 4056, Basel, Switzerland
| | - Antoine Gautier
- Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, 4056, Basel, Switzerland
- Paul Scherrer Institute, 5232, Villigen, Switzerland
| | | | - Stephan Grzesiek
- Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, 4056, Basel, Switzerland.
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Guarino F, Zinghirino F, Mela L, Pappalardo XG, Ichas F, De Pinto V, Messina A. NRF-1 and HIF-1α contribute to modulation of human VDAC1 gene promoter during starvation and hypoxia in HeLa cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148289. [PMID: 32810507 DOI: 10.1016/j.bbabio.2020.148289] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/05/2020] [Accepted: 08/11/2020] [Indexed: 02/07/2023]
Abstract
VDAC (Voltage Dependent Anion Channel) is a family of pore forming protein located in the outer mitochondrial membrane. Its channel property ensures metabolites exchange between mitochondria and the rest of the cell resulting in metabolism and bioenergetics regulation, and in cell death and life switch. VDAC1 is the best characterized and most abundant isoform, and is involved in many pathologies, as cancer or neurodegenerative diseases. However, little information is available about its gene expression regulation in normal and/or pathological conditions. In this work, we explored VDAC1 gene expression regulation in normal conditions and in the contest of some metabolic and energetic mitochondrial dysfunction and cell stress as example. The core of the putative promoter region was characterized in terms of transcription factors responsive elements both by bioinformatic studies and promoter activity experiments. In particular, we found an abundant presence of NRF-1 sites, together with other transcription factors binding sites involved in cell growth, proliferation, development, and we studied their prevalence in gene activity. Furthermore, upon depletion of nutrients or controlled hypoxia, as detected in various pathologies, we found that VDAC1 transcripts levels were significantly increased in a time related manner. VDAC1 promoter activity was also validated by gene reporter assays. According to PCR real-time experiments, it was confirmed that VDAC1 promoter activity is further stimulated when cells are exposed to stress. A bioinformatic survey suggested HIF-1α, besides NRF-1, as a most active TFBS. Their validation was obtained by TFBS mutagenesis and TF overexpression experiments. In conclusion, we experimentally demonstrated the involvement of both NRF-1 and HIF-1α in the regulation of VDAC1 promoter activation at basal level and in some peculiar cell stress conditions.
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Affiliation(s)
- Francesca Guarino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 64, 95123 Catania, Italy.
| | - Federica Zinghirino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 64, 95123 Catania, Italy
| | - Lia Mela
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 64, 95123 Catania, Italy
| | - Xena Giada Pappalardo
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 64, 95123 Catania, Italy
| | - François Ichas
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Université de Bordeaux, Bordeaux, France; INSERM, Laboratoire de Neurosciences Expérimentales et Cliniques, U-1084, Université de Poitiers, Poitiers, France
| | - Vito De Pinto
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 64, 95123 Catania, Italy; National Institute for Biostructures and Biosystems, Section of Catania, Rome, Italy.
| | - Angela Messina
- Department of Biological, Geological and Environmental Sciences, Section of Molecular Biology, University of Catania, Viale A. Doria 6, 95125 Catania, Italy; National Institute for Biostructures and Biosystems, Section of Catania, Rome, Italy
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