Ce programme s'adresse principalement au candidat issu de la biochimie ou d'un domaine connexe. La vie est en mutation, l'environnement est en transformation. Parmi ces orientations figurent les champs de recherche suivants:. Yves Bourbonnais.
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Toggle navigation. Have you forgotten your login? Journal articles. Christian Pruvost 2 AuthorId : Author. Philippe Minard 3 AuthorId : Author. Mariana Stein 1 AuthorId : Author. Paulette Decottignies 1 AuthorId : Author. Hide details. Abstract : Proline 40 in Escherichia coli thioredoxin is located close to the redox active site CysCys35 within the alpha2 helix. We have substituted Pro40 for Ala by using site-directed mutagenesis and expressed the mutant P40A in E. The effects of the mutation on the biophysical and biological properties of thioredoxin have been analyzed and compared with molecular dynamics simulations.
Modeling predicted that the replacement of Pro40 by Ala induced a displacement of the active site which exposes Trp31 to the solvent and opens a cleft located between helices alpha2 and alpha3. The solvation free energy SFE calculation also indicated that P40A became more hydrophobic as W31 became more accessible. These predictions were totally in agreement with the experimental results.
The mutant P40A exhibited chromatographic behavior and fluorescence properties very different from those of the wild-type WT protein, in relationship with the displacement of W The determination of the free energy of unfolding of P40A showed that the mutant was globally destabilized by 2. However, the effect of the mutation on the transition curve was highly unusual as the midpoint of the unfolding transition increased, indicating that some local structures were actually stabilized by the mutation.
Despite these structural modifications, neither the ability of the protein to reduce a chloroplastic enzyme nor its reactivity with the bacterial reductase decreased. The only functional difference was the higher stability of P40A in light activation of NADP-malate dehydrogenase under air, which suggests that the mutant was less rapidly re-oxidized than WT. Therefore, it can be concluded that Pro40 is not essential for maintaining the redox function of thioredoxin but rather is required for the stability of the protein.
Links full text. Structural and functional roles of a conserved proline residue in the alpha2 helix of Escherichia coli thioredoxin.. Protein Engineering , , 10 12 , pp. Metrics Record views. Contact support.
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