Plant low-molecular-weight phospholipase A2s (PLA2s) are structurally related to the animal secretory PLA2s and are present as a family of isoforms in rice (Oryza sativa) |
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Authors: | Ståhl Ulf Lee Michael Sjödahl Staffan Archer David Cellini Francesco Ek Bo Iannacone Rina MacKenzie Donald Semeraro Lucia Tramontano Eleonora Stymme Sten |
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Affiliation: | (1) Department of Plant Biology, Swedish University of Agricultural Sciences, P.O. Box 7080, 750 07 Uppsala, Sweden;(2) Department of Plant Breeding Research, Swedish University of Agricultural Sciences, Herman von Ehles v. 4-6, 268 31 Svalöv, Sweden;(3) Institute of Food Research, Norwich Research Park, Colney, Norwich, UK;(4) Metapontum Agrobios Srl, S.S. Ionica 106 Km. 448,2, 75010 Metaponto Mt, Italy |
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Abstract: | Recently, we purified to homogeneity and characterized a low-molecular-weight calcium-dependent phospholipase A2 (PLA2) from developing elm seed endosperm. This represented the first purified and characterized PLA2 from a plant tissue. The full sequences of two distinct but homologous rice (Oryza sativa) cDNAs are given here. These encode mature proteins of 119 amino acids (PLA2-I, preceded by a 19 amino acid signal peptide) and 128 amino acids (PLA2-II, preceded by a 25 amino acid signal peptide), and were derived from four expressed sequence tag (EST) clones. Both proteins were homologous to the N-terminal amino acid sequence of the elm PLA2. They contained twelve conserved cysteine residues and sequences that are likely to represent the Ca2+-binding loop and active-site motif, which are characteristic of animal secretory PLA2s. A soluble PLA2 activity was purified 145 000-fold from green rice shoots. This had the same biochemical characteristics as the elm and animal secretory PLA2s. The purified rice PLA2 consisted of two proteins, with a molecular weight of 12 440 and 12 920, that had identical N-terminal amino acid sequences. This sequence was different from but homologous to the PLA2-I and PLA2-II sequences. Taken together, the results suggest that at least three different low-molecular-weight PLA2s are expressed in green rice shoots. Southern blot analysis suggested that multiple copies of such genes are likely to occur in the rice and in other plant genomes. |
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Keywords: | calcium-dependent lipid metabolism Oryza sativa phospholipase A2 PLA2 |
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