Heteronuclear NMR spectroscopy of proteins encapsulated in cubic phase lipids

Thomas G Meikle; Ashish Sethi; David W Keizer; Jeffrey J Babon; Frances Separovic; Paul R Gooley; Charlotte E Conn; Shenggen Yao

doi:10.1016/j.jmr.2019.06.017

Heteronuclear NMR spectroscopy of proteins encapsulated in cubic phase lipids

J Magn Reson. 2019 Aug:305:146-151. doi: 10.1016/j.jmr.2019.06.017. Epub 2019 Jul 1.

Authors

Thomas G Meikle¹, Ashish Sethi², David W Keizer³, Jeffrey J Babon⁴, Frances Separovic⁵, Paul R Gooley², Charlotte E Conn¹, Shenggen Yao⁶

Affiliations

¹ School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia.
² Department of Biochemistry & Molecular Biology, The University of Melbourne, VIC 3010, Australia; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia.
³ Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia.
⁴ The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, VIC 3010, Australia.
⁵ Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia; School of Chemistry, The University of Melbourne, VIC 3010, Australia.
⁶ Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC 3010, Australia. Electronic address: shyao@unimelb.edu.au.

PMID: 31284168
DOI: 10.1016/j.jmr.2019.06.017

Abstract

Lipidic cubic phases, which form spontaneously via the self-assembly of certain lipids in an aqueous environment, are highly prospective nanomaterials with applications in membrane protein X-ray crystallography and drug delivery. Here we report ¹H-¹⁵N heteronuclear single/multiple quantum coherence (HSQC, HMQC) spectra of ¹⁵N-enriched proteins encapsulated in inverse bicontinuous lipidic cubic phases obtained on a standard commercial high resolution NMR spectrometer at ambient temperature. ¹⁵N-enriched proteins encapsulated in this lipidic cubic phase show: (i) no significant changes in tertiary structure, (ii) significantly reduced solvent chemical exchange of backbone amides, which potentially provides a novel concept for quantifying residue-specific hydration; and (iii) improved spectral sensitivity achieved with band-selective excitation short-transient (BEST) spectroscopy, which is attributed to the presence of an abundant source of ¹H nuclear spins originating from the lipid component of the cubic phase.

Keywords: Heteronuclear NMR spectroscopy; Lipidic cubic phase; Protein hydration; Sensitivity enhancement; Solvent exchange.

MeSH terms

Bacterial Proteins / chemistry*
Lipids / chemistry
Nitrogen Isotopes
Nuclear Magnetic Resonance, Biomolecular / methods*
Sensitivity and Specificity

Substances

Bacterial Proteins
Lipids
Nitrogen Isotopes