Ca2+-induced folding of a family 1.3 lipase with repetitive Ca2+ binding motifs at the C-terminus

In order to understand a role of the Ca2+ ion on the structure and function of a Ca2+-dependent family 1.3 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. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.