A. panamensis Photosystem I Preserves 1.4 Billion Years of Core Structure as Antenna Proteins Diverge
Updated
Updated · Quanta Magazine · Jun 10
A. panamensis Photosystem I Preserves 1.4 Billion Years of Core Structure as Antenna Proteins Diverge
1 articles · Updated · Quanta Magazine · Jun 10
Summary
A 2025 PNAS study found Anthocerotibacter panamensis kept the core architecture of photosystem I largely intact despite 1.4 billion years of evolutionary separation from other Gloeobacteria.
Cryo-EM data showed most change occurred in light-harvesting proteins, including the bacterium’s unusual paddle-shaped antenna, while the reaction center itself differed only slightly.
That pattern supports the idea that photosynthesis’ central machinery was fixed early, even as surrounding components and later structures such as thylakoids evolved to improve efficiency.
A. panamensis also lacks thylakoids and places its photosystems on the plasma membrane, traits that make Gloeobacteria a potential window into early cyanobacterial photosynthesis.
Researchers caution the microbe is not a fossil snapshot after 2.5 billion years of evolution, and say more early-branching species are needed to test how oxygenic photosynthesis began.