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Structural properties of caleosin: a MS and CD study
Zita Purkrtova1, Sabine d'Andrea, Pascale Jolivet
1UMR 206 Chimie Biologique, Agro Paris Tech, INRA, BP1, F-78850 Thiverval Grignon, France.
Archives of Biochemistry and Biophysics
|June 22, 2007
Summary
Arabidopsis thaliana caleosin (AtClo1) structure was investigated. This seed protein exists as monomers and dimers in solution and its secondary structure is sensitive to environmental polarity.
Area of Science:
- Plant biochemistry
- Protein structure analysis
Background:
- Caleosin (AtClo1) is a 27-kDa protein found in Arabidopsis thaliana seed lipid bodies.
- The native protein exhibits partial phosphorylation at serine 225 (S225).
Purpose of the Study:
- To investigate the covalent and secondary solution structure of Arabidopsis thaliana caleosin (AtClo1).
- To use bacterially expressed caleosin (recClo) as a model for structural studies.
Main Methods:
- Circular Dichroism (CD) spectroscopy was used to analyze secondary structure.
- CD spectra were measured in varying concentrations of aliphatic alcohols to assess media polarity effects.
Main Results:
- Bacterially expressed caleosin (recClo) lacks phosphorylation and features a disulfide bridge between cysteine residues C221 and C230.
- In solution, recClo exists as a mixture of monomers and covalent dimers.
- recClo exhibits a folded structure in aqueous solution with 16% alpha-helix and 29% beta-sheet content.
- The protein's secondary structure is significantly affected by the polarity of the surrounding medium.
Conclusions:
- The study elucidates the structural characteristics of Arabidopsis thaliana caleosin (AtClo1) in solution.
- Environmental polarity plays a crucial role in modulating the secondary structure of AtClo1.
