Structural and functional characterization of dihydrodiol dehydrogenase PahB recognizing high-molecular-weight PAH substrates.
Han Q, Tian L-L, Guo L, Cui R, Liu Z-S
Phytoremediation
Contaminated soil in vacant lots, brownfields, and roadside verges near your garden holds these same chemicals, and understanding how soil bacteria naturally destroy them is the first step toward engineering faster, living cleanups that don't require excavation.
Some bacteria living in dirty, polluted soil have evolved special proteins that can break down toxic chemicals left over from burning fuel, coal tar, and industrial processes. Researchers figured out the exact shape of one of these proteins and how it grips the toxic molecule to snap it apart. This knowledge could help scientists breed or engineer better bacteria to clean up contaminated ground more quickly and thoroughly.
Key Findings
The enzyme PahB can process dihydrodiol intermediates from four- and five-ring polycyclic aromatic hydrocarbons, including the carcinogen benzo[a]pyrene, making it unusually versatile compared to previously studied dehydrogenases.
Crystal structure analysis revealed a hydrophobic, methionine-rich binding pocket that accommodates bulky pollutant molecules, with a single methionine residue (M219) providing the conformational flexibility needed to handle oversized substrates.
This is the first structural characterization of a dehydrogenase capable of processing high-molecular-weight PAH intermediates, filling a major gap in understanding how microbes complete the full degradation pathway of carcinogenic soil pollutants.
chevron_right Technical Summary
Scientists discovered how a soil bacterium breaks down some of the most toxic environmental pollutants — the tar-like chemicals found in contaminated soils near roads, factories, and old industrial sites. By mapping the 3D structure of a key enzyme, they identified exactly how it grabs and dismantles these large, cancer-causing molecules.
Abstract Preview
Polycyclic aromatic hydrocarbons (PAHs), especially high-molecular-weight PAHs (HMW-PAHs), are persistent environmental pollutants that are difficult to remove and challenge environmental managemen...
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