Expression analysis and enzymatic characterization of phospholipase Cδ4 from olive flounder (Paralichthys olivaceus)

Phospholipase C delta 4 (PLC delta 4) plays a significant role in cell proliferation, tumorigenesis, and in an early stage of fertilization. Despite the characterization of the mammalian PLC delta 4, extensive study in aquatic organisms has not been carried out so far. Here, we performed the molecular and biochemical characterization of flat-fish Paralichthys olivaceus PLC delta 4 (PoPLC delta 4) to understand its enzymatic properties and physiological functions. The olive flounder PLC delta 4 cDNA has an open reading frame (ORF) of 2,268 bp, and encodes a 755 amino acid polypeptide with a predicted molecular weight of 86 kDa. All the characteristic domains found in mammalian PLC delta isoforms (PH domain, EF hands, an X-Y catalytic region, and a C2 domain) were found to be present in PoPLC delta 4. The mRNA expression analysis of PoPLC delta 4 showed that PoPLC delta 4 is predominantly expressed in the brain, eye and heart tissues. Like other mammalian PLC delta proteins, the enzyme activity of recombinant PoPLC delta 4 to phosphatidylinositol-4,5-bis-phosphate (PIP2) was noted to be concentration- and Ca2+-dependent. The structural features and biochemical characteristics of PoPLC delta 4 were found to be similar to those of mammalian PLC delta 4. This is the first demonstration of the expression analysis and enzymatic characterization of piscine PLC delta 4. (C) 2013 Elsevier Inc All rights reserved.