title: Characterization of an ultraviolet B-induced lipase in Arabidopsis.
abstract: An Arabidopsis expressed sequence tag clone, 221D24, encoding a lipase has been characterized using an antisense approach. The lipase gene is expressed during normal growth and development of Arabidopsis rosette leaves but is down-regulated as the leaves senesce. When plants are exposed to sublethal levels of UV-B radiation, expression of the lipase is strongly up-regulated. The lipase protein is localized in the cell cytosol and is present in all organs of Arabidopsis plants. Recombinant lipase protein produced in Escherichia coli preferentially hydrolyzed phospholipids, indicating that the gene encodes a phospholipase. Transgenic plants in which lipase expression is suppressed showed enhanced tolerance to UV-B stress but not osmotic stress and were unable to up-regulate PR-1 expression when irradiated with UV-B. The observations collectively indicate that the lipase is capable of deesterifying membrane phospholipids and is up-regulated in response to UV-B irradiation.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Maisie
authors.initials: M
authors.lastname: Lo
authors.forename: Catherine
authors.initials: C
authors.lastname: Taylor
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Linda
authors.initials: L
authors.lastname: Nowack
authors.forename: Tzann-Wei
authors.initials: TW
authors.lastname: Wang
authors.forename: John
authors.initials: J
authors.lastname: Thompson
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008969:Molecular Sequence Data; D010740:Phospholipases / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D010740:Phospholipases