It acts as both a cleaver and a binding tool


Blue-green algae (AKA cyanobacteria) have a superpower that likely helps them succeed as waterway invaders. They have an extraordinary ability to store energy and nitrogen in their cells when needed. But how exactly they do this remains only partially understood.

Researchers at McGill University and their collaborators at ETH Zurich have discovered an intriguing, hitherto unknown ability of enzymes (known as cyanophycine synthetases) that are active in creating these food reserves. Their findings, described in a recent article by Nature Communication, are not only scientifically surprising, but bring us closer to the possibility of using these environmentally friendly polymers for everything from bandages to biodegradable antiscalants to animal feed.

Enzymes such as cyanophycine synthetases (called polymerase enzymes because they synthesize long chains of polymers) usually require primers in the form of short “starter chains” to start assembling the long chains. Polymerases act as catalysts for a wide range of biological functions, from starting the process of RNA and DNA replication to converting glucose into glycogen as a means of storing energy for later use. Cyanophycin synthases from many different cyanobacteria were thought to need primers like all other polymerases, but then researchers spotted something new.

“We were working with several cyanophycin synthetases and discovered that one of them did not need to be primed,” says lead author Itai Sharon, a PhD student in biochemistry at McGill. “After three years of experiments, trying to figure out why not, we discovered that this cyanophycine synthase has a hidden reaction center within it that cleaves bonds between amino acids, instead of binding amino acids, which is the main job of this polymerase.”

Unlike all known polymerases

Researchers have found that cyanophycine synthetase can slowly make a very small number of long cyanophycin polymers in the absence of a primer, which the newly discovered reaction center cleaves into many short chains which are then used as primers for polymerization fast.

“We call cyanophycine synthetase a ‘Swiss army knife enzyme,'” says Martin Schmeing, corresponding author and director of McGill’s Structural Biology Research Center. an elegant and self-contained curing machine.”

“What makes it even more special is that these polymerases have been studied by many researchers for decades and decades. No one, including us, had noticed this before!”

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Materials provided by McGill university. Note: Content may be edited for style and length.


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