Abstract
Production, extraction, purification, and stabilization of integral membrane proteins are key steps for successful structural biology studies, in particular for X-ray crystallography or single particle microscopy. Here, we present the purification protocol of CntI from Pseudomonas aeruginosa, a new metallophore exporter of the Drug Metabolite Transporter (DMT) family involved in pseudopaline secretion. Subsequent to CntI purification, we optimized the buffer pH, salts, and additives by differential scanning fluorimetry (DSF), also known as Thermofluor Assay (TFA) or fluorescent thermal stability assay (FTSA), with the use of dye 1-AnilinoNaphthalene-8-Sulfonic acid (ANS), a fluorescent molecule compatible with detergents. After the buffer optimization, the purified CntI was analyzed by Size Exclusion Chromatography coupled with Multi-Angle Laser Light Scattering (SEC-MALLS), UV absorbance, and Refractive Index detectors, in order to determine the absolute molar mass of the protein–detergent complex, the detergent amount bound to the protein and the amount of protein-free detergent micelles. Altogether, these biophysical techniques give preliminary and mandatory information about the suitability of the purified membrane protein for further biophysical or structural investigations.
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References
Santos R, Ursu O, Gaulton A et al (2017) A comprehensive map of molecular drug targets. Nat Rev Drug Discov 16:19–34
Overington JP, Al-Lazikani B, Hopkins AL (2006) How many drug targets are there? Nat Rev Drug Discov 5:993–996
Stetsenko A, Guskov A (2017) An overview of the top ten detergents used for membrane protein crystallization. Crystals 7:197
Birch J, Axford D, Foadi J et al (2018) The fine art of integral membrane protein crystallisation. Methods 147:150–162
Errasti-Murugarren E, Bartoccioni P, Palacín M (2021) Membrane protein stabilization strategies for structural and functional studies. Membranes 11:155
Lhospice S, Gomez NO, Ouerdane L et al (2017) Pseudomonas aeruginosa zinc uptake in chelating environment is primarily mediated by the metallophore pseudopaline. Sci Rep 7:17132
Tsuchiya H, Doki S, Takemoto M et al (2016) Structural basis for amino acid export by DMT superfamily transporter YddG. Nature 534:417–420
Kohlstaedt M, von der Hocht I, Hilbers F et al (2015) Development of a Thermofluor assay for stability determination of membrane proteins using the Na(+)/H(+) antiporter NhaA and cytochrome c oxidase. Acta Crystallogr D Biol Crystallogr 71:1112–1122
Rath A, Glibowicka M, Nadeau VG et al (2009) Detergent binding explains anomalous SDS-PAGE migration of membrane proteins. Proc Natl Acad Sci 106:1760–1765
Slotboom DJ, Duurkens RH, Olieman K, Erkens GB (2008) Static light scattering to characterize membrane proteins in detergent solution. Methods 46:73–82
Feroz H, Kwon H, Peng J et al (2018) Improving extraction and post-purification concentration of membrane proteins. Analyst 143:1378–1386
Gobet A, Zampieri V, Magnard S et al (2023) The non-Newtonian behavior of detergents during concentration is increased by macromolecules, in trans, and results in their over-concentration. Biochimie 205:53–60
Chaptal V, Delolme F, Kilburg A et al (2017) Quantification of detergents complexed with membrane proteins. Sci Rep 7:41751
Strop P, Brunger AT (2005) Refractive index-based determination of detergent concentration and its application to the study of membrane proteins. Protein Sci Publ Protein Soc 14:2207–2211
Acknowledgments
We thank Dr. Pascal Arnoux for cloning and providing the expression plasmid of CntI in pET-TEV. We thank Dr. Daniel Picot for his help in peak integration of refractive index curves.
This work was supported by “Agence Nationale de la Recherche,” grant number ANR-20-CE11-0018).
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Mégret-Cavalier, M., Pozza, A., Cece, Q., Bonneté, F., Broutin, I., Phan, G. (2024). Starting with an Integral Membrane Protein Project for Structural Biology: Production, Purification, Detergent Quantification, and Buffer Optimization—Case Study of the Exporter CntI from Pseudomonas aeruginosa. In: Journet, L., Cascales, E. (eds) Bacterial Secretion Systems . Methods in Molecular Biology, vol 2715. Humana, New York, NY. https://doi.org/10.1007/978-1-0716-3445-5_26
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DOI: https://doi.org/10.1007/978-1-0716-3445-5_26
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