Modulation of plant nuclear matrix nucleolytic activity and specificity may result from interaction of nuclease-protein 14-3-3 complex with inner nuclear membrane lipids

Plant cell nuclear matrix depleted in lipids exhibited approximately 50% lower endonucleolytic activity attributed to 32 kDa nuclease. Supplementation of delipidated matrix with phospholipids, sterols and glycolipids resulted in the recovery of nuclease activity. The extent of recovery is dependent upon the type of lipid used for reconstitution. The most effective (over 97%) in recovery of the nucleolytic activity were PC, PE, DGDG and stigmasterol. Some recovery is also observed when other natural amphiphilic molecules are studied (resorcinolic lipids). Recombinant plant protein 14-3-3 showed ability for direct interaction with lipid monolayers. The interaction was confirmed by analysis of the monolayer collected from the subphase after incubation with protein 14-3-3. Deletion of the 12 kDa N-terminal fragment of the protein 14-3-3 abolished its ability for binding to lipid monolayer. The results suggest that in vivo direct interaction of protein 14-3-3 with nuclear envelope lipids may participate in modulation of the nuclease 32 kDa activity. A postulated model of the interactions is discussed.