title: Characterization of a cDNA encoding Arabidopsis secretory phospholipase A2-alpha, an enzyme that generates bioactive lysophospholipids and free fatty acids.
abstract: Phospholipase A2s (PLA2s) are enzymes that liberate lysophospholipids and free fatty acids (FFAs) from membrane phospholipids in response to hormones and other external stimuli. This report describes the cloning and functional characterization of a PLA2 cDNA from Arabidopsis thaliana, AtsPLA2-alpha, which represents one of four secretory PLA2 (sPLA2) genes in Arabidopsis. The encoded protein is 148-amino acid polypeptide and is predicted to contain a 20-amino acid signal peptide at its amino terminus. The predicted mature form (Mr=14,169) of AtsPLA2-alpha exhibited approximately 5 times the specific activity of its pre-processed form. Different from animal sPLA2s, AtsPLA2-alpha showed a significant preference for the acyl group linoleic acid over palmitic acid in phospholipid hydrolysis. Like some animal sPLA2s, however, it has a slight preference for phosphatidylethanolamine over phosphatidylcholine as the substrate. The specific activity of AtsPLA2-alpha continuously increased as the Ca2+ concentration was increased to 10 mM, and the optimal pH range was very broad and biphasic between 6 and 11. AtsPLA2-alpha transcript was detected at low levels in roots, stems, leaves, and flowers but not in siliques.
authors.affiliation: Department of Horticulture, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706, USA.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Ryu
authors.forename: Hyoung Yool
authors.initials: HY
authors.lastname: Lee
authors.forename: Jed H
authors.initials: JH
authors.lastname: Doelling
authors.forename: Jiwan P
authors.initials: JP
authors.lastname: Palta
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary; D054513:Group IV Phospholipases A2; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D054467:Phospholipases A2; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D020033:Protein Isoforms; D011994:Recombinant Proteins; D010741:Phospholipases A; D054513:Group IV Phospholipases A2; D054467:Phospholipases A2