Evidence for pattern development: engulfing adds function (Introduction)

by David Turell , Tuesday, March 30, 2021, 21:28 (1334 days ago) @ David Turell

Another study confirms this form of evolutionary spread of photosynthesis into different organisms:

https://www.sciencedaily.com/releases/2021/03/210330100330.htm

"Up until now, how cryptophytes acquired the proteins used to capture and funnel sunlight to be used by the cell had molecular biologists scratching their heads. They already knew that the protein was part of a sort of antenna that the organism used to convert sunlight into energy. They also knew that the cryptophyte had inherited some antenna components from its photosynthetic ancestors -- red algae, and before that cyanobacteria, one of the earliest lifeforms on earth that are responsible for stromatolites.

"But how the protein structures fit together in the cryptophyte's own, novel antenna structure remained a mystery -- until Prof. Curmi, PhD student Harry Rathbone and colleagues from University of Queensland and University of British Columbia pored over the electron microscope images of the antenna protein from a progenitor red algal organism made public by Chinese researchers in March 2020.

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"'We provide a direct link between two very different antenna systems and open the door for discovering exactly how one system evolved into a different system -- where both appear to be very efficient in capturing light," he says.

"'Photosynthetic algae have many different antenna systems which have the property of being able to capture every available light photon and transferring it to a photosystem protein that converts the light energy to chemical energy."

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"As study lead author, PhD student Harry Rathbone explains, when a single-celled organism swallows another, it can enter a relationship of endosymbiosis, where one organism lives inside the other and the two become inseparable.

"'Often with algae, they'll go and find some lunch -- another alga -- and they'll decide not to digest it. They'll keep it to do its bidding, essentially," Mr Rathbone says. "And those new organisms can be swallowed by other organisms in the same way, sort of like a matryoshka doll."

"In fact, this is likely what happened when about one and a half billion years ago, a cyanobacterium was swallowed by another single-celled organism. The cyanobacteria already had a sophisticated antenna of proteins that trapped every photon of light. But instead of digesting the cyanobacterium, the host organism effectively stripped it for parts -- retaining the antenna protein structure that the new organism -- the red algae -- used for energy.

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"'In going from cyanobacteria that are photosynthetic, to everything else on the planet that is photosynthetic, some ancient ancestor gobbled up a cyanobacteria which then became the cell's chloroplast that converts sunlight into chemical energy.

"'And the deal between the organisms is sort of like, I'll keep you safe as long as you do photosynthesis and give me energy."

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"'Paul's novel approach was to search for ancestral proteins on the basis of shape rather than similarity in amino acid sequence," she says.

"'By searching the 3D structures of two red algal multi-protein complexes for segments of protein that folded in the same way as the cryptophyte protein, he was able to find the missing puzzle piece.'"

Comment: It was important for the evolutionary process to develop wide spread photosynthesis to free up enough oxygen to reach 21% of our atmosphere. And thanks to Lynn Margolis for recognizing the way to add a function by ingulfing another organism