title: Novel lysophospholipid acyltransferase PLAT1 of Aurantiochytrium limacinum F26-b responsible for generation of palmitate-docosahexaenoate-phosphatidylcholine and phosphatidylethanolamine.
abstract: N-3 polyunsaturated fatty acids (PUFA), such as docosahexaenoic acid (DHA, 22:6n-3), have been reported to play roles in preventing cardiovascular diseases. The major source of DHA is fish oils but a recent increase in the global demand of DHA and decrease in fish stocks require a substitute. Thraustochytrids, unicellular marine protists belonging to the Chromista kingdom, can synthesize large amounts of DHA, and, thus, are expected to be an alternative to fish oils. DHA is found in the acyl chain(s) of phospholipids as well as triacylglycerols in thraustochytrids; however, how thraustochytrids incorporate DHA into phospholipids remains unknown. We report here a novel lysophospholipid acyltransferase (PLAT1), which is responsible for the generation of DHA-containing phosphatidylcholine and phosphatidylethanolamine in thraustochytrids. The PLAT1 gene, which was isolated from the genomic DNA of Aurantiochytrium limacinum F26-b, was expressed in Saccharomyces cerevisiae, and the FLAG-tagged recombinant enzyme was characterized after purification with anti-FLAG affinity gel. PLAT1 shows wide specificity for donor substrates as well as acceptor substrates in vitro, i.e, the enzyme can adopt lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine and lysophosphatidylinositol as acceptor substrates, and 15:0/16:0-CoA and DHA-CoA as donor substrates. In contrast to the in vitro experiment, only lysophosphatidylcholine acyltransferase and lysophosphatidylethanolamine acyltransferase activities were decreased in plat1-knockout mutants, resulting in a decrease of 16:0-DHA-phosphatidylcholine (PC) [PC(38:6)] and 16:0-DHA-phosphatidylethanolamine (PE) [PE(38:6)], which are two major DHA-containing phospholipids in A. limacinum F26-b. However, the amounts of other phospholipid species including DHA-DHA-PC [PC(44:12)] and DHA-DHA-PE [PE(44:12)] were almost the same in plat-knockout mutants and the wild-type. These results indicate that PLAT1 is the enzyme responsible for the generation of 16:0-DHA-PC and 16:0-DHA-PE in the thraustochytrid.
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Abe
authors.affiliation: Institute for Advanced Biosciences, Keio University, Kakuganji, Tsuruoka, Yamagata, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Ikeda
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Nutahara
authors.affiliation: Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hayashi
authors.affiliation: Faculty of Pharma-Sciences, Teikyo University, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamashita
authors.affiliation: Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai-shi, Aichi, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Taguchi
authors.affiliation: Graduate School of Natural Science, Konan University, Higashinada-ku, Kobe, Hyogo, Japan; Institute for Integrative Neurobiology, Konan University, Higashinada-ku, Kobe, Hyogo, Japan.
authors.forename: Kosaku
authors.initials: K
authors.lastname: Doi
authors.affiliation: Institute for Integrative Neurobiology, Konan University, Higashinada-ku, Kobe, Hyogo, Japan; Faculty of Science and Engineering, Konan University, Higashinada-ku, Kobe, Hyogo, Japan.
authors.forename: Daiske
authors.initials: D
authors.lastname: Honda
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Okino
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan; Bio-Archtechture Center, Kyushu University, Fukuoka, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ito
mesh_terms: D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000737:chemistry / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D042541:Intracellular Space / Q000201:enzymology; D008246:Lysophospholipids / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019308:Palmitic Acid / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D058009:Stramenopiles / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D008246:Lysophospholipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D012337:RNA, Ribosomal, 18S; D004281:Docosahexaenoic Acids; D019308:Palmitic Acid; C483858:phosphatidylethanolamine; D008243:1-Acylglycerophosphocholine O-Acyltransferase
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