When Bacillus subtilis bacteria face a critical choice—burn energy quickly or build new cells slowly—they rely on a molecular traffic controller discovered by researchers at the University of Greifswald. That controller is acetyl coenzyme A, a central metabolic molecule that acts like a hub connecting nutrient breakdown with the synthesis of proteins, carbohydrates, and lipids. Until recently, scientists didn't understand exactly how bacteria coordinate the production and decomposition of this crucial molecule. Now, a team led by Prof. Dr. Michael Lammers has uncovered the mechanism, and the findings, published in Nature Communications, rewrite what we know about bacterial metabolism.
The story begins with a choice every cell faces when nutrients are plentiful: gain energy or create building blocks for growth. Acetyl-CoA sits at the heart of that decision. It's produced inside bacterial cells from three ingredients: acetic acid (the universal cellular energy source), ATP, and coenzyme A, all brought together by an enzyme called AcsA. But AcsA doesn't work all the time—it can be switched on or off like a light switch through a small biochemical modification called lysine acetylation. When that modification is present, the enzyme sleeps; when it's absent, the enzyme springs to life and starts making acetyl-CoA.
The real breakthrough, however, lies in understanding what controls that switch. The Greifswald team, including doctoral candidate and first author Markus Janetzky, identified a protein sensor called AcuB that monitors the cell's energy state. AcuB binds directly to another enzyme, AcuC, which is a deacetylase—essentially a eraser that removes the modification from AcsA and activates it. Here's where cellular intelligence comes in: AcuB only inhibits AcuC when the cell's energy is running low, which it detects by binding to adenosine monophosphate (AMP). Unlike ATP, which signals abundant energy, AMP is the red light warning of energy depletion.
This creates an elegant safeguard. The cell only produces acetyl-CoA—an energy-expensive process—when it has enough power reserves to actually carry out vital functions like growth or repair. "By binding different adenine nucleotides, AcuB acts like a sensor of cellular energy status," Lammers explained. "It indirectly adapts the activity of the enzyme used to produce acetyl coenzyme A to the metabolic state of the cell."
The discovery emerged from collaborative work across the University of Greifswald's Faculty of Mathematics and Natural Sciences. Molecular dynamics simulations by Norman Geist from Prof. Dr. Mihaela Delcea's research group proved essential to mapping how proteins change shape and function during this process. Lammers emphasized that understanding these dynamic shifts in protein structure is crucial: "Our results show how important the dynamics of changes in protein shape are for their function."
The implications extend far beyond bacterial curiosity. Bacillus subtilis has been a research focus at Greifswald for decades, and this new mechanism opens pathways to understanding metabolic coordination across microbial life. It's a reminder that inside every cell, even the smallest bacterium, elegant solutions to metabolic problems have evolved—solutions that took humanity decades of careful science to finally see.