How iron and metabolic constraints can aid gene discovery for photosynthesis and biofuel production

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The single-cell green alga Chromochloris zofingiensis is an emerging model organism for photosynthesis and metabolism research. Previous research has shown that with the addition of glucose, Chromochloris zofingiensis shuts off photosynthesis, reroutes its metabolism, and accumulates high amounts of lipids (biofuel precursors) and astaxanthin (a high-value antioxidant).

A team of scientists from the University of California, Berkeley, and EMSL has now shown that cells grown with an iron supplement and glucose could maintain photosynthesis and thylakoids, the membranes where photosynthetic energy transfer occurs, while still accumulating lipids. The research is published in the journal Nature Communications.

Proteomic samples analyzed by EMSL researchers revealed the metabolic wiring of cells associated with the loss of photosynthesis and lipid accumulation. Transmission electron microscopy conducted using EMSL capabilities allowed for the visualization of thylakoids, starch, and lipid accumulation.

Together with physiological analyses, the team determined that glucose-mediated photosynthesis repression is associated with a reprioritization of iron resources toward respiratory instead of photosynthetic complexes, as well as a ferredoxin-dependent desaturase pathway that supported lipid storage over thylakoid lipid synthesis.

Furthermore, the team conducted comparative evolutionary genomics on green algae and vascular plants to show how iron and metabolic trophic constraints can aid in gene discovery for photosynthesis and biofuel production.

This study shows that at the base of the photosynthetic evolutionary tree, Chromochloris zofingiensis is a simple organism that can be used to study energy, nutrients, and photosynthesis, and that these results can provide a roadmap to enhance the production of bioenergy crops and bioproducts.

More information: Tim L. Jeffers et al, Iron rescues glucose-mediated photosynthesis repression during lipid accumulation in the green alga Chromochloris zofingiensis, Nature Communications (2024). DOI: 10.1038/s41467-024-50170-x

Journal information: Nature Communications

Provided by Environmental Molecular Sciences Laboratory