Intersubunit Coupling Enables Fast CO-Fixation by Reductive Carboxylases.

Enoyl-CoA carboxylases/reductases (ECRs) are some of the most efficient CO-fixing enzymes described to date. However, the molecular mechanisms underlying the extraordinary catalytic activity of ECRs on the level of the protein assembly remain elusive. Here we used a combination of ambient-temperature X-ray free electron laser (XFEL) and cryogenic synchrotron experiments to study the structural organization of the ECR from .

Awakening the Sleeping Carboxylase Function of Enzymes: Engineering the Natural CO-Binding Potential of Reductases.

Developing new carbon dioxide (CO) fixing enzymes is a prerequisite to create new biocatalysts for diverse applications in chemistry, biotechnology and synthetic biology. Here we used bioinformatics to identify a "sleeping carboxylase function" in the superfamily of medium-chain dehydrogenases/reductases (MDR), i.e.

The marine bacterium Phaeobacter inhibens secures external ammonium by rapid buildup of intracellular nitrogen stocks.

Reduced nitrogen species are key nutrients for biological productivity in the oceans. Ammonium is often present in low and growth-limiting concentrations, albeit peaks occur during collapse of algal blooms or via input from deep sea upwelling and riverine inflow. Autotrophic phytoplankton exploit ammonium peaks by storing nitrogen intracellularly.