Structural, dynamic, and evolutionary determinants of substrate binding in the tetrameric 6-phosphogluconate dehydrogenase from Gluconobacter oxydans.
Maturana P, Villalobos P, Roversi P, Cabrera R
Carbon Metabolism
Every fruit, vegetable, and grain on your plate relies on the same sugar-processing chemistry studied here, and cracking how these enzymes lock onto their targets in bacteria is a stepping stone to engineering crops that handle drought or disease stress more efficiently.
Plants, animals, and bacteria all use a set of reactions to break down sugar and generate the cellular energy they need to grow and defend themselves. Scientists studying a bacterium found that one crucial enzyme in this process uses a pair of molecular 'clasps' — like a latch and a lock — to grab its sugar target and carry out its job. Understanding this mechanism at atomic detail helps scientists figure out how to tweak similar enzymes in crop plants to improve yield or resilience.
Key Findings
A high-resolution (2.0 Å) crystal structure revealed the enzyme uses a novel 'latch and lock' mechanism involving two C-terminal protein elements to grip its substrate, rather than the domain-folding motion seen in related enzymes.
A single amino acid, His328, was identified as the linchpin: removing it through mutagenesis sharply reduced the enzyme's catalytic efficiency, confirming its central role.
Thermodynamic measurements showed substrate binding is strongly enthalpy-driven, meaning the reaction releases heat as it forms a tight, ordered network of chemical bonds — a hallmark of a highly specific, evolved binding pocket.
chevron_right Technical Summary
Scientists solved the precise 3D shape of a bacterial enzyme that processes sugar in a pathway shared by all living things — including plants — revealing a unique molecular locking mechanism that controls the enzyme's activity.
Abstract Preview
6-Phosphogluconate dehydrogenases (6PGDHs) catalyze a key oxidative step in the oxidative pentose phosphate pathway (oxPPP), a route essential for NAD(P)H generation and carbon metabolism in bacter...
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