Nanodevice Sheds Light on Early Cyanobacterial Evolution

Nanodevice Sheds Light on Early Cyanobacterial Evolution
by Sophie Jenkins
London, UK (SPX) May 19, 2025

An international research team has provided fresh insights into the origins of oxygenic photosynthesis by revealing the structure of a light-harvesting nanodevice within one of the planet's most ancient cyanobacteria lineages. This breakthrough, detailed in the Proceedings of the National Academy of Sciences, offers a rare glimpse into how early life forms harnessed sunlight, setting the stage for Earth's oxygen-rich atmosphere.

The study, led by researchers from Queen Mary University of London, focused on Photosystem I (PSI), a crucial protein complex that converts light into electrical energy. The team isolated PSI from Anthocerotibacter panamensis, a recently identified cyanobacterium species that diverged from all other known cyanobacteria roughly 3 billion years ago. Unlike its distant cyanobacterial relatives, which separated around 1.4 billion years ago, this species lacks the more familiar stacked membrane structures, known as thylakoids, typically used for efficient photosynthesis.

"While we can't go back in time to directly observe these ancient cyanobacteria," said Dr Ming-Yang Ho of National Taiwan University, the study's lead author, "studying early-branching species like A. panamensis lets us peer into our planet's distant biological past."

Most photosynthetic organisms, including algae and plants, organize their light-capturing machinery into thylakoids, akin to layered solar panels. In contrast, A. panamensis relies on a simpler, single-membrane arrangement, limiting its efficiency and restricting it to low-light environments.

"With this PSI structure now in hand," noted co-author Dr Christopher Gisriel from the University of Wisconsin-Madison, "we can pinpoint which aspects of photosynthesis are ancient and which represent more recent evolutionary innovations."

Their analysis revealed that, despite significant genetic drift, the fundamental architecture of PSI remains largely unchanged, forming a unique three-leaf-clover configuration with more than 300 embedded pigments, including chlorophylls and carotenoids.

Dr Tanai Cardona from Queen Mary University of London concluded, "This discovery suggests that even three billion years ago, the machinery for oxygenic photosynthesis had already achieved remarkable complexity. Tracing the true origin of this process may require looking even further back, to a time before cyanobacteria themselves evolved."

Research Report:Structure and evolution of photosystem I in the early-branching cyanobacterium Anthocerotibacter panamensis