Uniform isotope labeling of a eukaryotic seven-transmembrane helical protein in yeast enables high-resolution solid-state NMR studies in the lipid environment
Abstract Overexpression of isotope-labeled multi-spanning eukaryotic membrane proteins for structural NMR studies is often challenging. On the one hand, difficulties with achieving proper folding, membrane insertion, and native-like post-translational modifications frequently disqualify bacterial expression systems. On the other hand, eukaryotic cell cultures can be prohibitively expensive. One of the viable alternatives, successfully used for producing proteins for solution NMR studies, is yeast expression systems, particularly
Pichia pastoris. We report on successful implementation and optimization of isotope labeling protocols, previously used for soluble secreted proteins, to produce homogeneous samples of a eukaryotic seven-transmembrane helical protein, rhodopsin from
Leptosphaeria maculans. Even in shake-flask cultures, yields exceeded 5 mg of purified uniformly 13C,15N-labeled protein per liter of culture. The protein was stable (at least several weeks at 5°C) and functionally active upon reconstitution into lipid membranes at high protein-to-lipid ratio required for solid-state NMR. The samples gave high-resolution 13C and 15N solid-state magic angle spinning NMR spectra, amenable to a detailed structural analysis. We believe that similar protocols can be adopted for challenging mammalian targets, which often resist characterization by other structural methods.
- Content Type Journal Article
- Pages 1-11
- DOI 10.1007/s10858-011-9473-9
- Authors
- Ying Fan, Department of Physics, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Lichi Shi, Department of Physics, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Vladimir Ladizhansky, Department of Physics, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
- Leonid S. Brown, Department of Physics, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada
Source: Journal of Biomolecular NMR