Plant terpene biosynthesis: organelles synergy
Jara M. Al-Mousawi, Manish L. Raorane
Isoprenoids and their derivatives, terpenes, have emerged as compounds of substantial pharmacological interest. Their diverse bioactivities, encompassing sedative, antiviral, antimicrobial, anti-inflammatory, and antineoplastic properties, have stimulated extensive research into their biosynthetic pathways.
Higher plants utilize two distinct pathways for isoprene unit generation: the cytosolic mevalonic acid (MVA) pathway and the plastidial 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. While traditionally viewed as compartmentalized, increasing evidence suggests a complex interplay between these pathways. This crosstalk has been implicated in the biosynthesis of various isoprenoid classes, including sesquiterpenes, sterols, and monoterpenes.
Despite growing recognition of this phenomenon, the precise mechanisms underlying isoprenoid transport between organelles remain elusive. While prenyl diphosphates have been proposed as potential candidates, definitive experimental evidence supporting their translocation across organelle membranes is lacking. Furthermore, the subcellular localization of the MVA pathway has been refined to include the endoplasmic reticulum and peroxisome, challenging the classical cytosolic view.
The dynamic architecture of plant organelles, characterized by structures such as stromules, matrixules, and peroxules, provides a potential framework for enhanced inter-organelle communication. We hypothesize that these organelle extensions facilitate the exchange of isoprenoid precursors.
To investigate this hypothesis, we will utilize tobacco BY-2 suspension cells as a model system. Our approach involves three key strategies:
- Organelle-specific overexpression: Overexpressing terpene pathway genes in specific organelles to induce metabolic crosstalk.
- Organelle imaging: Employing chemical elicitors and fluorescent protein tags to visualize organelle interactions and dynamics.
- Metabolic flux analysis: Utilizing positionally labeled 13C sugars to quantify isoprenoid pathway crosstalk.
By elucidating the mechanisms governing isoprenoid pathway crosstalk, this research aims to identify novel targets for metabolic engineering and optimize terpene production in plant cell cultures.
