title: Circular dichroism and the secondary structure of the ROF2 protein from Arabidopsis thaliana.
abstract: The protein ROF2 from the plant Arabidopsis thaliana acts as a heat stress modulator, being involved in the long-term acquired thermotolerance of the plant. Here we investigate the relationship between the biological function and the structure of ROF2, inferred by circular dichroism (CD) spectroscopy. The far-UV CD spectra, analyzed with the CDPro and DICHROWEB program packages, yield the percentages of α-helices, β-sheets, unordered regions, turns and poly(Pro)II-helices in the secondary structure of ROF2. According to the analysis, the percentages of the structural elements of ROF2 are about 40% for β-sheets, 30% for unordered regions, 17% for turns, 10% for poly(Pro)II-helices and 3% for α-helices. The near-UV CD spectra suggest that ROF2 proteins can associate, forming super-secondary structures. Our CD experiments performed at temperatures between 5 °C and 97 °C indicate that the thermal denaturation of ROF2 caused by a raise in temperature up to 55 °C is followed by a thermal refolding of the protein as the temperature is raised further. The new secondary structure, acquired around 65 °C, remains stable up to 97 °C. The structural stability of ROF2 at high temperatures might play an important role in the experimentally observed thermotolerance of Arabidopsis thaliana.
authors.affiliation: Faculty of Physics, West University of Timisoara, Blvd. Vasile Parvan No. 4, 300223 Timisoara, Romania. llighezan@physics.uvt.ro
authors.forename: Liliana
authors.initials: L
authors.lastname: Lighezan
authors.forename: David
authors.initials: D
authors.lastname: Meiri
authors.forename: Adina
authors.initials: A
authors.lastname: Breiman
authors.forename: Adrian
authors.initials: A
authors.lastname: Neagu
mesh_terms: D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D019696:Peptidylprolyl Isomerase / Q000737:chemistry*; D055550:Protein Stability; D017433:Protein Structure, Secondary; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; D019696:Peptidylprolyl Isomerase; C574787:ROF2 protein, Arabidopsis