The surprising Swiss-Army-knife-like functions of a powerful enzyme
Blue-green algae (AKA cyanobacteria) have a superpower which likely helps them be highly successful as invaders of waterways. They have an extraordinary ability to store energy and nitrogen in their cells for times of need. But how exactly they do so remains only partly understood.
Now researchers from 捆绑SM社区 and their collaborators at ETH Zurich have uncovered an intriguing hitherto unknown ability of the enzymes (known as cyanophycin synthetases) that are active in creating these food reserves. Their findings, described in a recent paper in , are not only scientifically surprizing, but take us a step closer to being able to use these environmentally friendly polymers for everything from bandages to biodegradable antiscalants to animal food.
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Enzymes such as cyanophycin synthetases (called polymerase enzymes because they synthesize long chains of polymers) usually require primers in the form of short 鈥渟tarter chains鈥� to start assembling the long chains. Polymerases act as catalysts for a wide range of biological functions, from kickstarting the process of RNA and DNA replication to converting glucose into glycogen as a way of storing energy for later use. Cyanophycin synthetases from many different cyanobacteria were thought to need primers like all the other polymerases, but then the researchers spotted something new.
鈥淲e were working with several cyanophycin synthetases and found that one of them didn鈥檛 need to be given primer,鈥� says lead author Itai Sharon, a 捆绑SM社区 PhD student in Biochemistry. 鈥淎fter three years of experiments, trying to figure out why not, we discovered that this cyanophycin synthetase had a hidden reaction centre within it that cleaves bonds between amino acids, instead of linking amino acids, which is this polymerase鈥檚 main job.鈥�
Unlike all known polymerases
The researchers discovered that cyanophycin synthetase could slowly make extremely small numbers of long cyanophycin polymers in absence of primer, which the newly discovered reaction centre cleaves into many short chains that are then used as primers for fast polymerization.
鈥淲e call cyanophycin synthetase a 鈥楽wiss army knife enzyme鈥� says Martin Schmeing, corresponding author and Director of the . 鈥淚t combines three enzymatic functions 鈥� two bond-making and one bond-breaking 鈥� into one elegant, self-sufficient polymerizing machine.鈥�
鈥淲hat makes it even more special is that these polymerases have been studied by many researchers for decades and decades. Nobody, including us, had noticed this before!鈥�
| Citation: Sharon I, Pinus S, Grogg M, Moitessier N, Hilvert D, Schmeing TM. A cryptic third active site in cyanophycin synthetase creates primers for polymerization. Nature Communications 2022 Jul 7; 13:3923. |
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