German researchers discover complex enzymatic processes with cryo-electron microscopy

In Germany, high-resolution cryo-electron microscopy makes it possible to study complex enzymatic processes in detail. With this method, a research team of the University of Potsdam and Humboldt-Universität Berlin succeeded in characterizing the CODH/ACS enzyme complex in detail. They discovered that the complex moves in the course of chemical reactions and thus determines the reaction sequence. Their results have been published in the journal Nature Catalysis.

Before the start of photosynthesis in Earth’s history and the accumulation of oxygen in the atmosphere, anaerobic microorganisms lived here, which do not need oxygen for their metabolism. Anaerobic carbon fixation is considered one of the oldest and most efficient processes of its species and also plays a central role in modern ecosystems—for example in volcanic swamps or in the animal digestive tract. The enzyme complex CO-dehydrogenase-acetyl-CoA-synthase (CODH/ACS) essential for this has been preserved in microorganisms for over 3.5 billion years.

Catalysis, i.e. the acceleration of chemical processes in CODH/ACS, is based on various nickel-iron metal clusters that convert carbon dioxide into the important biomolecule acetyl-CoA in several reaction steps. The efficiency of this reaction makes CODH/ACS a promising enzyme candidate for biofuel production from carbon dioxide.

Researchers from the University of Potsdam and Humboldt-Universität Berlin have now used high-resolution cryo-electron microscopy (cryo-EM) for the first time to elucidate the catalytic cycle of CODH/ACS. Cryo-EM has a wide range of applications and can be used for the structural analysis of various enzymes and biopolymers.