Geraniol, an acyclic monoterpenoid of substantial value extracted from the essential oils of various aromatic plants, holds significant commercial and industrial importance in the realms of food, cosmetics, medicine, and bioenergy. Geraniol synthase, which is responsible for geraniol production, has been identified in only several plant species to date. Here, we present the first cloning and characterization of a geraniol synthase (PgfTPS) from Penicillium griseofulvum. This enzyme demonstrates pronounced specificity in catalyzing the conversion of geranyl diphosphate into geraniol. Moreover, through protein modeling and site-directed mutagenesis, we have identified key active-site residues crucial for the catalytic function of PgfTPS. Finally, we utilized engineered Saccharomyces cerevisiae as a host for PgfTPS expression to facilitate geraniol production. Our findings not only advance the development of efficient biocatalysts for geraniol generation but also establish a fundamental basis for further exploration into fungal monoterpene biosynthesis.
Aquilaria sinensis (Lour.) Gilg is one of the most important plant resources that produce agarwood, a fragrant resinous wood of high commercial value. Sesquiterpenes, the predominant constituents and important criterion for the quality of agarwood, play an essential role in stress and defence responses. However, the biosynthesis mechanisms of volatile sesquiterpenes and genes involved in these processes have not been comprehensively studied in Aquilaria . In this study, four sesquiterpene synthase genes were cloned from 3-year-old A. sinensis and identified using a yeast expression system as novel genes critical for sesquiterpene biosynthesis. AsTPS14, which catalyses the production of equal amounts of 4,11-selinadiene and α-selinene, is the first selinene synthase identified in Aquilaria . AsTPS13 can catalyse the production of three oxygenated sesquiterpenes, namely, β-eudesmol, γ-eudesmol and hinesol. AsTPS3 and AsTPS10 are two α-humulene synthases that can catalyse the production of α-humulene, and AsTPS3 is the most efficient α-humulene synthase in A. sinensis . Findings in this study reveal the diversity of sesquiterpene synthases and their multi-faceted functions, and offer further insights into the molecular mechanism of agarwood sesquiterpene biosynthesis. This work provides a solid theoretical and experimental foundation for molecularly assisted breeding of A. sinensis and efficient synthesis of sesquiterpenes.
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