Fecha de publicación: 20/01/2025 Fuente: Digital CSIC Título: Molecular and Biochemical Characterization of Olive 4-Hydroxyphenyl Pyruvate Dioxygenase Involved in the Biosynthesis of Tocopherols Present in Virgin Olive Oil
Autor: Sánchez, Rosario; Expósito, Jesús; García-Vico, Lourdes; Luaces, Pilar; Sanz, Carlos; Pérez Rubio, Ana Gracia
Resumen: Olive (Olea europaea) fruit contains high amounts of tocopherols that are responsible, along with secoiridoid phenolic compounds, for most of the antioxidant and anti-inflammatory properties of virgin olive oil. This study focuses on the molecular and biochemical characterization of olive 4-hydroxyphenyl pyruvate dioxygenase (OeHPPD) catalyzing the biosynthesis of homogentisic acid, which constitutes the phenolic residue in the tocopherol molecule. OeHPPD is a cytoplasmic enzyme with a molecular weight of 49.8 kDa and a predicted tertiary structure very similar to the Arabidopsis enzyme that suggests similar catalytic mechanisms. OeHPPD has an estimated Kcat of 75.26 s-1 and catalytic efficiency (Km/Kcat) of 0.145 μM-1 s-1 with 4-hydroxyphenyl pyruvate as the substrate. The expression analysis in fruits from selected olive cultivars harvested at different ripening stages indicates that the OeHPPD gene is temporally regulated and cultivar-dependent. Moreover, the analysis of OeHPPD expression in fruits affected by drought stress suggests that HPPD is involved in olive environmental adaptation.
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