High-resolution structure of monomeric photosystem I from Thermosynechococcus vestitus.

High-resolution cryo-EM structure of monomeric Photosystem I from Thermosynechococcus vestitus reveals all subunits except PsaL at 1.8 Å resolution.

• Why it matters: Understanding the structure of monomeric PSI is crucial for insights into its stability and function, especially since PSI exists in both trimeric and monomeric forms in cyanobacteria, impacting photosynthetic efficiency and regulation.
• What they did: The study developed a protocol to isolate active monomeric PSI using detergent dissociation, then analyzed its stability with spectroscopic methods and determined its structure via cryo-EM, identifying lipid and detergent molecules around the complex.
• The result: The structure suggests a red-shifted chlorophyll and highlights the influence of detergents and lipids on PSI stability and oligomeric state, with evidence of transient Cyt c 6 binding near P700 pigments.