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Mutation analysis of violaxanthin de-epoxidase identifies substrate-binding sites and residues involved in catalysis.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2010 Jul 30; Vol. 285 (31), pp. 23763-70. Date of Electronic Publication: 2010 May 27. - Publication Year :
- 2010
-
Abstract
- Plants are able to deal with variable environmental conditions; when exposed to strong illumination, they safely dissipate excess energy as heat and increase their capacity for scavenging reacting oxygen species. Both these protection mechanisms involve activation of the xanthophyll cycle, in which the carotenoid violaxanthin is converted to zeaxanthin by violaxanthin de-epoxidase, using ascorbate as the source of reducing power. In this work, following determination of the three-dimensional structure of the violaxanthin de-epoxidase catalytic domain, we identified the putative binding sites for violaxanthin and ascorbate by in silico docking. Amino acid residues lying in close contact with the two substrates were analyzed for their involvement in the catalytic mechanism. Experimental results supported the proposed substrate-binding sites and point to two residues, Asp-177 and Tyr-198, which are suggested to participate in the catalytic mechanism, based on complete loss of activity in mutant proteins. The role of other residues and the mechanistic similarity to aspartic proteases and epoxide hydrolases are discussed.
- Subjects :
- Amino Acid Sequence
Ascorbic Acid chemistry
Aspartic Acid chemistry
Binding Sites
Catalysis
Molecular Conformation
Molecular Sequence Data
Mutagenesis, Site-Directed
Protein Conformation
Protein Structure, Tertiary
Sequence Homology, Amino Acid
Tyrosine chemistry
Xanthophylls chemistry
Zeaxanthins
DNA Mutational Analysis
Oxidoreductases chemistry
Plants enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 285
- Issue :
- 31
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 20507981
- Full Text :
- https://doi.org/10.1074/jbc.M110.115097