Ca2+‐induced folding of a family I.3 lipase with repetitive Ca2+ binding motifs at the C‐terminus

Abstract
In order to understand a role of the Ca2+ ion on the structure and function of a Ca2+‐dependent family I.3 lipase from Pseudomonas sp. MIS38, apo‐PML, holo‐PML, holo‐PML*, and the N‐terminal domain alone (N‐fragment) were prepared and biochemically characterized. Apo‐PML and holo‐PML represent refolded proteins in the absence and presence of the Ca2+ ion, respectively. Holo‐PML* represents a holo‐PML dialyzed against 20 mM Tris–HCl (pH 7.5). The results suggest that the C‐terminal domain of PML is almost fully unfolded in the apo‐form and its folding is induced by Ca2+ binding. The folding of this C‐terminal domain may be required to make a conformation of the N‐terminal catalytic domain functional.