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Updated: Jun 21, 2026
Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies
Published on: March 6, 2013
Conformational studies of peptides representing a segment of TM7 from H+-VO-ATPase in SDS micelles
Afonso M S Duarte1, Edwin R de Jong, Rob B M Koehorst
1Laboratory of Biophysics, Wageningen University, 6703 HA Wageningen, The Netherlands.
Abstract:
The conformation of a transmembrane peptide, sMTM7, encompassing the cytoplasmic hemi-channel domain of the seventh transmembrane section of subunit a from V-ATPase from Saccharomyces cerevisiae solubilized in SDS solutions was studied by circular dichroism (CD) spectroscopy and fluorescence spectroscopy of the single tryptophan residue of this peptide. The results show that the peptide adopts an alpha-helical conformation or aggregated beta-sheet depending on the peptide-to-SDS ratio used. The results are compared with published data about a longer version of the peptide (i.e., MTM7). It is concluded that the bulky, positively charged arginine residue located in the center of both peptides has a destabilizing effect on the helical conformation of the SDS-solubilized peptides, leading to beta-sheet formation and subsequent aggregation.
Insights
The conformation of Saccharomyces cerevisiae V-ATPase transmembrane peptide sMTM7 shifts between alpha-helical and beta-sheet structures based on peptide-to-SDS ratio, influenced by a central arginine residue.
Area of Science:
- Biochemistry
- Structural Biology
- Membrane Proteins
Background:
- The V-ATPase (Vesicular-transporting ATPase) is crucial for cellular processes.
- Understanding transmembrane protein conformation is key to their function.
- Subunit a of yeast V-ATPase contains a cytoplasmic hemi-channel domain.
Purpose of the Study:
- To investigate the conformational behavior of the sMTM7 peptide from yeast V-ATPase.
- To determine how peptide-to-SDS ratio affects the secondary structure of sMTM7.
- To elucidate the role of a central arginine residue in peptide conformation.
Main Methods:
- Circular dichroism (CD) spectroscopy to analyze secondary structure.
- Fluorescence spectroscopy utilizing a single tryptophan residue.
- Solubilization of the peptide in sodium dodecyl sulfate (SDS) solutions.
Main Results:
- The sMTM7 peptide adopts an alpha-helical conformation at certain peptide-to-SDS ratios.
- The peptide transitions to an aggregated beta-sheet structure at other ratios.
- Comparison with the MTM7 peptide suggests a destabilizing effect of a central arginine residue.
Conclusions:
- The central arginine residue in sMTM7 and MTM7 destabilizes helical structure in SDS.
- This destabilization promotes beta-sheet formation and aggregation.
- Conformational plasticity is influenced by both peptide sequence and detergent environment.
