title: The α/β hydrolase CGI-58 and peroxisomal transport protein PXA1 coregulate lipid homeostasis and signaling in Arabidopsis.
abstract: COMPARATIVE GENE IDENTIFICATION-58 (CGI-58) is a key regulator of lipid metabolism and signaling in mammals, but its underlying mechanisms are unclear. Disruption of CGI-58 in either mammals or plants results in a significant increase in triacylglycerol (TAG), suggesting that CGI-58 activity is evolutionarily conserved. However, plants lack proteins that are important for CGI-58 activity in mammals. Here, we demonstrate that CGI-58 functions by interacting with the PEROXISOMAL ABC-TRANSPORTER1 (PXA1), a protein that transports a variety of substrates into peroxisomes for their subsequent metabolism by β-oxidation, including fatty acids and lipophilic hormone precursors of the jasmonate and auxin biosynthetic pathways. We also show that mutant cgi-58 plants display changes in jasmonate biosynthesis, auxin signaling, and lipid metabolism consistent with reduced PXA1 activity in planta and that, based on the double mutant cgi-58 pxa1, PXA1 is epistatic to CGI-58 in all of these processes. However, CGI-58 was not required for the PXA1-dependent breakdown of TAG in germinated seeds. Collectively, the results reveal that CGI-58 positively regulates many aspects of PXA1 activity in plants and that these two proteins function to coregulate lipid metabolism and signaling, particularly in nonseed vegetative tissues. Similarities and differences of CGI-58 activity in plants versus animals are discussed.
authors.affiliation: U.S. Department of Agriculture-Agricultural Research Service, U.S. Arid-Land Agricultural Research Center, Maricopa, Arizona 85138, USA.
authors.forename: Sunjung
authors.initials: S
authors.lastname: Park
authors.forename: Satinder K
authors.initials: SK
authors.lastname: Gidda
authors.forename: Christopher N
authors.initials: CN
authors.lastname: James
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Horn
authors.forename: Nicholas
authors.initials: N
authors.lastname: Khuu
authors.forename: Damien C
authors.initials: DC
authors.lastname: Seay
authors.forename: Jantana
authors.initials: J
authors.lastname: Keereetaweep
authors.forename: Kent D
authors.initials: KD
authors.lastname: Chapman
authors.forename: Robert T
authors.initials: RT
authors.lastname: Mullen
authors.forename: John M
authors.initials: JM
authors.lastname: Dyer
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism; D050612:Fatty Acid Transport Proteins / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D006706:Homeostasis; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D050356:Lipid Metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D011485:Protein Binding; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014280:Triglycerides / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D007210:Indoleacetic Acids; D008164:Luminescent Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D014280:Triglycerides; C011006:jasmonic acid; D000217:Acyltransferases; C018764:2-acylglycerophosphate acyltransferase; D006867:Hydrolases; D000251:Adenosine Triphosphatases; C456843:At4g39850 protein, Arabidopsis