Biology subjects

Olry, A.

Publications and source records attributed to Olry, A..

4 recordsLinked to original sources

bioRxiv2026

A membrane-bound aromatic O-prenyltransferase catalyzes the last reaction step in citrus auraptene biosynthesis

Plants produce a variety of O-prenylated aromatics that exhibit biological activities beneficial to human health, and the presence of the O-prenyl moiety is often crucial to their functions. However, most aromatic O-prenylation genes remain unknown in plants. In this study, we report the molecular identification of an aromatic O-prenyltransferase (PT) involved in the biosynthesis of auraptene (7-geranyloxycoumarin), a citrus metabolite known for its preservative effect on human cognitive function. Based on in silico screening focusing on the membrane-bound PT family, CpPT4 was isolated as a candidate from grapefruit (Citrus x paradisi), an auraptene-rich species. Enzymatic characterization demonstrated that recombinant CpPT4 specifically catalyzes umbelliferone 7-O-geranyltransferase activity to form auraptene, which differs from the enzymatic functions of known O-PTs. This enzyme also catalyzed aromatic N-prenylation to produce a new-to-nature auraptene analog. Regarding organ- and organellar-specific localization, it is strongly suggested that CpPT4 functions in the outer pericarp plastids, where auraptene is expected be formed. Furthermore, we found that CpPT4 orthologs are widely distributed in citrus genomes. Intriguingly, mandarins and their descendant species possess dysfunctional orthologs, which is consistent with the low accumulation of auraptene and its downstream metabolites in these species. This study provides an example of the contribution of the UbiA superfamily to O-prenylated aromatic biosynthesis. Moreover, CpPT4 can be useful as a tool in the synthetic biology-based production of auraptene and its analogs, as well as a molecular marker in the breeding of auraptene-rich citrus varieties.

biochemistry↗

bioRxiv2026

First O-demethylation activity in Arabidopsis specialized metabolism resolves the missing step in esculetin biosynthesis

Coumarins are phenylpropanoid-derived specialized metabolites that contribute to plant defence, shape plant-microbe interactions in the rhizosphere, and promote iron acquisition. In Arabidopsis thaliana, a model plant for iron-responsive coumarin metabolism, the enzymatic origin of the catecholic coumarin esculetin has long remained unresolved. Here we identify the first O-demethylation reaction in Arabidopsis specialized metabolism and show that 2-oxoglutarate- and Fe(II)-dependent dioxygenases catalyze scopoletin 6-O-demethylation to form esculetin. We designate these enzymes scopoletin 6-O-demethylases (S6ODs) and validate their activity through biochemical characterization, together with metabolomic profiling and independent loss-of-function mutant lines providing genetic evidence in planta. Disruption of S6OD activity remodels coumarin profiles and alters plant performance under limited iron availability, indicating that esculetin biosynthesis contributes to plant responses under these conditions. Our findings resolve the long-sought missing step in esculetin biosynthesis. It establishes O-demethylation as a previously unrecognized reaction in Arabidopsis specialized metabolism and suggest that 2OGD-mediated O-demethylation is recurrently recruited during evolution of plant metabolism, with implications for metabolic engineering and improvement of iron acquisition traits in crops.

plant biology↗

bioRxiv2024

Using lineage-specific patterns to understand convergence of enzymatic functions led to the identification of Moraceae-specific P450s involved in furanocoumarin biosynthesis

O_LISpecialized metabolites are molecules involved in plants interaction with their environment. Elucidating their biosynthetic pathways is a challenging but rewarding task, leading to societal applications and ecological insights. Furanocoumarins emerged multiple times in Angiosperms, raising the question of how different enzymes evolved into catalyzing identical reactions. C_LIO_LITo identify enzymes producing lineage-specific metabolites, an evolutionary-based approach was developed and applied to furanocoumarin biosynthesis in Ficus carica (Moraceae). This led to the characterization of CYP71B129-131a, three P450 enzymes whose evolution of the function was investigated using phylogenetics, structural comparisons and site-directed mutagenesis. C_LIO_LICYP71B129 and CYP71B130,131a were found to hydroxylate umbelliferone (coumarin) and xanthotoxin (furanocoumarin), respectively. Results suggest that CYP71Bs xanthotoxin hydroxylase activity results from duplications and functional divergence of umbelliferone hydroxylase genes. Structural comparisons highlighted an amino acid affecting CYP71Bs substrate specificity, which may play a key role in allowing xanthotoxin hydroxylation in several P450 subfamilies. C_LIO_LICYP71B130-131a characterization validates the proposed enzyme-discovery approach, which can be applied to different pathways and help to avoid the classic bottlenecks of specialized metabolism elucidation. The CYP71Bs also exemplify how furanocoumarin-biosynthetic enzymes can stem from coumarin-biosynthetic ones and provides insights into the molecular mechanisms underlying the multiple emergences of xanthotoxin hydroxylation in distant P450 subfamilies. C_LI

plant biology↗

bioRxiv2017

Scopoletin 8-hydroxylase: a novel enzyme involved in coumarin biosynthesis and iron-deficiency responses in Arabidopsis

HighlightA strongly iron-responsive gene of previously unknown function, At3g12900, encodes a scopoletin 8-hydroxylase involved in coumarin biosynthesis and plays an important role in the iron uptake strategy in Arabidopsis.\n\nAbstractIron (Fe) deficiency represents a serious agricultural problem, particularly in alkaline soils. Secretion of coumarins by Arabidopsis thaliana roots is induced under Fe-deficiency. An essential enzyme for the biosynthesis of major Arabidopsis coumarins, scopoletin and its derivatives, is Feruloyl-CoA 6-Hydroxylase1 (F6'H1) that belongs to a large enzyme family of the 2-oxoglutarate and Fe(II)-dependent dioxygenases. Another member of this family that is a close homologue of F6H1 and is encoded by a strongly Fe-responsive gene, At3g12900, is functionally characterized in the presented work. We purified the At3g12900 protein heterologously expressed in Escherichia coli and demonstrated that it is involved in the conversion of scopoletin into fraxetin via hydroxylation at the C8-position. Consequently, it was named scopoletin 8-hydroxylase (S8H). Its function in plant cells was confirmed by the transient expression of S8H protein in Nicotiana benthamiana leaves followed by the metabolite profiling and the biochemical and ionomic characterization of Arabidopsis s8h knockout lines grown under various regimes of Fe availability. Our results indicate that S8H is involved in coumarin biosynthesis as part of the Fe acquisition machinery.

plant biology↗