N-terminal EF-hand-like domain is required for phosphoinositide-specific phospholipase C activity in Arabidopsis thaliana

Phosphoinositide-specific phospholipase C's (PI-PLCs) are ubiquitous in euk aryotes, from plants to animals, and catalyze the hydrolysis of phosphatidy linositol 4,5-bisphosphate into the two second messengers inositol 1,4,5-tr isphosphate and diacylglycerol. in animals, four distinct subfamilies of PI -PLCs have been identified, and the three-dimensional structure of one rat isozyme, PLC-delta1, determined. Plants appear to contain only one gene fam ily encoding PI-PLCs, The catalytic properties of plant PI-PLCs are very si milar to those of animal enzymes, However, very little is known about the r egulation of plant PI-PLCs. All plant PI-PLCs comprise three domains, X, Y and C2, which are also conserved in isoforms from animals and yeast, We her e show that one PI-PLC isozyme from Arabidopsis thaliana, AtPLC2, is predom inantly localized in the plasma membrane, and that the conserved N-terminal domain may represent an EF-hand domain that is required for catalytic acti vity but not for lipid binding. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.