title: Bile Acid Sodium Symporter BASS6 Can Transport Glycolate and Is Involved in Photorespiratory Metabolism inArabidopsis thaliana.
abstract: Photorespiration is an energy-intensive process that recycles 2-phosphoglycolate, a toxic product of the Rubisco oxygenation reaction. The photorespiratory pathway is highly compartmentalized, involving the chloroplast, peroxisome, cytosol, and mitochondria. Though the soluble enzymes involved in photorespiration are well characterized, very few membrane transporters involved in photorespiration have been identified to date. In this work,Arabidopsis thalianaplants containing a T-DNA disruption of the bile acid sodium symporter BASS6 show decreased photosynthesis and slower growth under ambient, but not elevated CO2Exogenous expression of BASS6 complemented this photorespiration mutant phenotype. In addition, metabolite analysis and genetic complementation of glycolate transport in yeast showed that BASS6 was capable of glycolate transport. This is consistent with its involvement in the photorespiratory export of glycolate from Arabidopsis chloroplasts. An Arabidopsis double knockout line of both BASS6 and the glycolate/glycerate transporter PLGG1 (bass6, plgg1) showed an additive growth defect, an increase in glycolate accumulation, and reductions in photosynthetic rates compared with either single mutant. Our data indicate that BASS6 and PLGG1 partner in glycolate export from the chloroplast, whereas PLGG1 alone accounts for the import of glycerate. BASS6 and PLGG1 therefore balance the export of two glycolate molecules with the import of one glycerate molecule during photorespiration.
authors.affiliation: Global Change and Photosynthesis Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Urbana, Illinois 61801.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Paul F
authors.identifier: http://orcid.org/0000-0001-7885-7096
authors.initials: PF
authors.lastname: South
authors.affiliation: Global Change and Photosynthesis Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Urbana, Illinois 61801.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Berkley J
authors.identifier: http://orcid.org/0000-0001-5932-6468
authors.initials: BJ
authors.lastname: Walker
authors.affiliation: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Amanda P
authors.identifier: http://orcid.org/0000-0001-5918-8093
authors.initials: AP
authors.lastname: Cavanagh
authors.affiliation: Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra ACT 0200, Australia.
authors.forename: Vivien
authors.identifier: http://orcid.org/0000-0002-9232-1287
authors.initials: V
authors.lastname: Rolland
authors.affiliation: Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra ACT 0200, Australia.
authors.forename: Murray
authors.initials: M
authors.lastname: Badger
authors.affiliation: Global Change and Photosynthesis Research Unit, U.S. Department of Agriculture/Agricultural Research Service, Urbana, Illinois 61801 d-ort@illinois.edu.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801.|Department of Plant Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Donald R
authors.identifier: http://orcid.org/0000-0002-5435-4387
authors.initials: DR
authors.lastname: Ort
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D006016:Glycolates / Q000378:metabolism*; D009154:Mutation; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D006016:Glycolates; D002245:Carbon Dioxide