PsaL protein drives cyanobacteria light-conversion plasticity
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- NLR and Montana State University researchers investigated how the PsaL subunit of cyanobacterial photosystem I (PSI) influences the protein complex's ability to capture light and drive photochemistry, publishing their findings in the Journal of Biological Chemistry.
- Using pepsin proteolysis, the team found that cyanobacteria lacking the oxygen reduction reaction (ORR) pathway have a more exposed PsaL environment than wild-type cells, indicating PsaL sits farther from neighboring PSI subunits and reshaping how pigments bind.
- PsaL availability cascades to adjacent PSI monomers, altering how the light-harvesting antenna channels energy through the complex and demonstrating PSI's structural plasticity in response to environmental conditions.
- ORR-deficient cyanobacteria compensated for their missing excess-light pathway by increasing carotenoid abundance in PSI, effectively producing more of what researcher Cara Lubner called 'nature's sunscreen' under fluctuating light conditions.
- Carotenoid composition also shifted in ORR PSI molecules to absorb different wavelengths, suggesting cyanobacteria can retune their light-harvesting machinery when standard energy-balancing routes are unavailable.
- Senior NLR chemistry researcher Cara Lubner said the work addresses a fundamental knowledge gap that could help engineers develop microbes converting sunlight into useful products more efficiently for biofuels, bulk chemicals, and pharmaceuticals.
Why it matters: The study pinpoints PsaL, carotenoid levels, and PSI monomer-trimer balance as adjustable knobs for bioengineers designing cyanobacteria that convert sunlight into fuels (jet, marine, rocket) and chemicals. By explaining how microbes already self-tune light capture, the NLR team offers a roadmap for building strains that perform that conversion more efficiently — a concrete step toward scalable biomanufacturing.
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