title: Systematic phenotypic screen of Arabidopsis peroxisomal mutants identifies proteins involved in β-oxidation.
abstract: Peroxisomes are highly dynamic and multifunctional organelles essential to development. Plant peroxisomes accommodate a multitude of metabolic reactions, many of which are related to the β-oxidation of fatty acids or fatty acid-related metabolites. Recently, several dozens of novel peroxisomal proteins have been identified from Arabidopsis (Arabidopsis thaliana) through in silico and experimental proteomic analyses followed by in vivo protein targeting validations. To determine the functions of these proteins, we interrogated their transfer DNA insertion mutants with a series of physiological, cytological, and biochemical assays to reveal peroxisomal deficiencies. Sugar dependence and 2,4-dichlorophenoxybutyric acid and 12-oxo-phytodienoic acid response assays uncovered statistically significant phenotypes in β-oxidation-related processes in mutants for 20 of 27 genes tested. Additional investigations uncovered a subset of these mutants with abnormal seed germination, accumulation of oil bodies, and delayed degradation of long-chain fatty acids during early seedling development. Mutants for seven genes exhibited deficiencies in multiple assays, strongly suggesting the involvement of their gene products in peroxisomal β-oxidation and initial seedling growth. Proteins identified included isoforms of enzymes related to β-oxidation, such as acyl-CoA thioesterase2, acyl-activating enzyme isoform1, and acyl-activating enzyme isoform5, and proteins with functions previously unknown to be associated with β-oxidation, such as Indigoidine synthase A, Senescence-associated protein/B12D-related protein1, Betaine aldehyde dehydrogenase, and Unknown protein5. This multipronged phenotypic screen allowed us to reveal β-oxidation proteins that have not been discovered by single assay-based mutant screens and enabled the functional dissection of different isoforms of multigene families involved in β-oxidation.
authors.affiliation: Michigan State University-Department of Energy Plant Research Laboratory (G.C.-R., J.H.) andPlant Biology Department (J.H.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Cassin-Ross
authors.affiliation: Michigan State University-Department of Energy Plant Research Laboratory (G.C.-R., J.H.) andPlant Biology Department (J.H.), Michigan State University, East Lansing, Michigan 48824 huji@msu.edu.
authors.forename: Jianping
authors.initials: J
authors.lastname: Hu
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D007521:Isocitrate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D020675:Peroxisomes / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008565:Membrane Proteins; C499192:PEX14 protein, Arabidopsis; D012097:Repressor Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; C025999:12-oxophytodienoic acid; D007521:Isocitrate Dehydrogenase; C588248:ICDH protein, Arabidopsis; C004764:4-(2,4-dichlorophenoxy)butyric acid