Sunday, April 02, 2023

Soaking up far-red sunlight with a helix-shaped nanotube structure

Amazing stuff! Note helical shaped not cylindrical! 

Photosynthesis instead of environmentally hazardous solar panels!

".. the researchers describe a helix-shaped nanotube structure that forms within photosynthetic organisms called cyanobacteria. ...
According to their findings, the helical nanotubes harvest light photons from the far-red part of the light spectrum and deliver the photons for conversion into chemical energy during photosynthesis. These tiny, nanotube “devices” are deployed in low-light environments ...
Researchers have found that in low-light conditions, certain species of cyanobacteria activate a gene cluster that launches the production of proteins known as far-red light phycobiliproteins. These phycobiliproteins assemble themselves into helical nanotubes, distinct from previously discovered, similar proteins that produce cylindrical structures. The cylinder-shaped structures collect photons from the visible light colors in the solar spectrum, such as yellow and orange, whereas the helical nanotubes collect photons from the invisible, far-red portion of the solar spectrum, the researchers say. ...
Cryo-electron microscopy, which flash-freezes biomolecular samples and pelts them with electrons to produce images of molecules, allowed the researchers to see the helical shape of the nanotubes and how they were assembled. Time-resolved absorption spectroscopy, which looks at the way a material’s absorbance changes after it is exposed to light, allowed the researchers to track how quickly energy is transferred through the nanotubes — and the route the energy takes. ..."

From the abstract:
"To compete in certain low-light environments, some cyanobacteria express a paralog of the light-harvesting phycobiliprotein, allophycocyanin (AP), that strongly absorbs far-red light (FRL). Using cryo–electron microscopy and time-resolved absorption spectroscopy, we reveal the structure-function relationship of this FRL-absorbing AP complex (FRL-AP) that is expressed during acclimation to low light and that likely associates with chlorophyll a–containing photosystem I. FRL-AP assembles as helical nanotubes rather than typical toroids due to alterations of the domain geometry within each subunit. Spectroscopic characterization suggests that FRL-AP nanotubes are somewhat inefficient antenna; however, the enhanced ability to harvest FRL when visible light is severely attenuated represents a beneficial trade-off. The results expand the known diversity of light-harvesting proteins in nature and exemplify how biological plasticity is achieved by balancing resource accessibility with efficiency."

Soaking up sunlight with a microscopic molecular device | YaleNews A Yale-led team of chemists has identified a tiny “device” that helps certain photosynthetic organisms collect sunlight.

Helical allophycocyanin nanotubes absorb far-red light in a thermophilic cyanobacterium (open access)


Fig. 1. Overview of FRL-AP helical nanotube structure.




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