Structural basis for the catalytic mechanism of phosphothreonine lyase.

Salmonella SpvC belongs to a new enzyme family designated phosphothreonine lyases that irreversibly inactivate mitogen-activated protein kinases. The crystal structure of SpvC reported here reveals that the two phosphorylated residues in the substrate peptide predominantly mediate its recognition by SpvC. Substrate-induced conformational changes in SpvC sequester the phosphothreonine in a completely solvent-free environment, preventing the hydrolysis of the phosphate group and facilitating the elimination reaction.