title: Identification of a triacylglycerol lipase in the diatom Phaeodactylum tricornutum.
abstract: Diatoms accumulate triacylglycerols (TAGs) as storage lipids, but the knowledge about the molecular mechanisms of lipid metabolism is still sparse. Starting from a partial sequence for a putative TAG-lipase of the diatom Phaeodactylum tricornutum retrieved from the data bases, we have identified the full length coding sequence, tgl1. The gene encodes an 813 amino acid sequence that shows distinct motifs for so called "true" TAG-lipases [EC 3.1.1.3] that have been functionally characterized in model organisms like Arabidopsis thaliana and Saccharomyces cerevisiae. These lipases mediate the first initial step of TAG breakdown from storage lipids. To test whether Tgl1 can act as a TAG-lipase, a His-tagged version was overexpressed in Escherichia coli and the protein indeed showed esterase activity. To identify the TAG degrading function of Tgl1 in P. tricornutum, knock-down mutant strains were created using an antisense RNA approach. In the mutant cell lines the relative tgl1-mRNA-level was reduced up to 20% of that of the wild type, accompanied by a strong increase of TAG in the lipid extracts. In spite of the TAG accumulation, the polar lipid species pattern appeared to be unchanged, confirming the TAG-lipase function of Tgl1.
authors.affiliation: Plant Cell Physiology, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Barka
authors.affiliation: Plant Cell Physiology, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Angstenberger
authors.affiliation: Merck Stiftungsprofessur für Molekulare Biotechnologie, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany.
authors.forename: Tilman
authors.initials: T
authors.lastname: Ahrendt
authors.affiliation: Merck Stiftungsprofessur für Molekulare Biotechnologie, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Lorenzen
authors.affiliation: Merck Stiftungsprofessur für Molekulare Biotechnologie, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany; Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Max-von-Laue-Straße 15, 60438 Frankfurt am Main, Germany.
authors.forename: Helge B
authors.initials: HB
authors.lastname: Bode
authors.affiliation: Plant Cell Physiology, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Biozentrum, 60438 Frankfurt am Main, Germany. Electronic address: c.buechel@bio.uni-frankfurt.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Büchel
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017377:Diatoms / Q000201:enzymology* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D055785:Gene Knockdown Techniques; D005838:Genotype; D006868:Hydrolysis; D007700:Kinetics; D008049:Lipase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D016372:RNA, Antisense; D011994:Recombinant Proteins; D014280:Triglycerides; D008049:Lipase
keywords: Antisense; Lipase; Lipids; Polyunsaturated fatty acids