Two Glu/Asp residues cooperatively mediate an early step of ATP hydrolysis in GHKL ATPases MutL and GyrB.

Cooperative action of two conserved Glu/Asp residues is essential for early ATP hydrolysis in GHKL ATPases, with mutations impairing activity in human disease variants.

• Why it matters: Understanding the precise catalytic mechanism of GHKL ATPases is crucial because these enzymes regulate vital biological processes and are linked to human disease through variants of uncertain significance.
• What they did: The study used mutagenesis, ATPase and ATP-binding assays, and X-ray crystallography on Aquifex aeolicus MutL and GyrB to investigate the roles of two conserved acidic residues in ATP hydrolysis, revealing their cooperative function.
• The result: Findings show that the two residues work together to activate nucleophilic water, refining the catalytic model and enabling better interpretation of disease-associated variants, with evolutionary insights suggesting remodeling in some lineages.