The Roles of β-Oxidation and Cofactor Homeostasis in Peroxisome Distribution and Function in Arabidopsis thaliana.
Key steps of essential metabolic pathways are housed in plant peroxisomes. We conducted a microscopy-based screen for anomalous distribution of peroxisomally targeted fluorescence in Arabidopsis thaliana This screen uncovered 34 novel alleles in 15 genes affecting oil body mobilization, fatty acid β-oxidation, the glyoxylate cycle, peroxisome fission, and pexophagy. Partial loss-of-function of lipid-mobilization enzymes conferred peroxisomes clustered around retained oil bodies without other notable defects, suggesting that this microscopy-based approach was sensitive to minor perturbations, and that fatty acid β-oxidation rates in wild type are higher than required for normal growth. We recovered three mutants defective in PECTIN METHYLESTERASE31, revealing an unanticipated role in lipid mobilization for this cytosolic enzyme. Whereas mutations reducing fatty acid import had peroxisomes of wild-type size, mutations impairing fatty acid β-oxidation displayed enlarged peroxisomes, possibly caused by excess fatty acid β-oxidation intermediates in the peroxisome. Several fatty acid β-oxidation mutants also displayed defects in peroxisomal matrix protein import. Impairing fatty acid import reduced the large size of peroxisomes in a mutant defective in the PEROXISOMAL NAD+TRANSPORTER (PXN), supporting the hypothesis that fatty acid accumulation causes pxn peroxisome enlargement. The diverse mutants isolated in this screen will aid future investigations of the roles of β-oxidation and peroxisomal cofactor homeostasis in plant development.
Department of Biosciences, Rice University, Houston, Texas 77005.
Mauro A
0000-0001-7087-1184
MA
Rinaldi
Department of Biosciences, Rice University, Houston, Texas 77005.
Ashish B
AB
Patel
Department of Biosciences, Rice University, Houston, Texas 77005.
Jaeseok
J
Park
Department of Biosciences, Rice University, Houston, Texas 77005.
Koeun
K
Lee
Department of Biology, Washington University in St. Louis, Missouri 63130.
Lucia C
0000-0002-7600-7204
LC
Strader
Department of Biosciences, Rice University, Houston, Texas 77005 bartel@rice.edu.
Bonnie
0000-0002-6367-346X
B
Bartel
D000483:Alleles; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003067:Coenzymes / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D006706:Homeostasis; D009154:Mutation; D010084:Oxidation-Reduction; D020675:Peroxisomes / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; D003067:Coenzymes; D005227:Fatty Acids
PME31; PXN; fatty acid β-oxidation; lipid mobilization; peroxisome