title: The Impact of the Branched-Chain Ketoacid Dehydrogenase Complex on Amino Acid Homeostasis in Arabidopsis.
abstract: The branched-chain amino acids (BCAAs) Leu, Ile, and Val are among nine essential amino acids that must be obtained from the diet of humans and other animals, and can be nutritionally limiting in plant foods. Despite genetic evidence of its importance in regulating seed amino acid levels, the full BCAA catabolic network is not completely understood in plants, and limited information is available regarding its regulation. In this study, transcript coexpression analyses revealed positive correlations among BCAA catabolism genes in stress, development, diurnal/circadian, and light data sets. A core subset of BCAA catabolism genes, including those encoding putative branched-chain ketoacid dehydrogenase subunits, is highly expressed during the night in plants on a diel cycle and in prolonged darkness. Mutants defective in these subunits accumulate higher levels of BCAAs in mature seeds, providing genetic evidence for their function in BCAA catabolism. In addition, prolonged dark treatment caused the mutants to undergo senescence early and overaccumulate leaf BCAAs. These results extend the previous evidence that BCAAs can be catabolized and serve as respiratory substrates at multiple steps. Moreover, comparison of amino acid profiles between mature seeds and dark-treated leaves revealed differences in amino acid accumulation when BCAA catabolism is perturbed. Together, these results demonstrate the consequences of blocking BCAA catabolism during both normal growth conditions and under energy-limited conditions.
authors.affiliation: Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Cheng
authors.identifier: http://orcid.org/0000-0003-0863-0384
authors.initials: C
authors.lastname: Peng
authors.affiliation: Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Sahra
authors.identifier: http://orcid.org/0000-0001-6470-235X
authors.initials: S
authors.lastname: Uygun
authors.affiliation: Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Shin-Han
authors.identifier: http://orcid.org/0000-0001-6470-235X
authors.initials: SH
authors.lastname: Shiu
authors.affiliation: Department of Plant Biology (C.P., S.-H.S., R.L.L.), Department of Energy Plant Research Laboratory (C.P., S.U.), Genetics Program (S.U., S.-H.S.), and Department of Biochemistry and Molecular Biology (R.L.L.), Michigan State University, East Lansing, Michigan 48824 lastr@msu.edu.
authors.forename: Robert L
authors.identifier: http://orcid.org/0000-0001-6974-9587
authors.initials: RL
authors.lastname: Last
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) / Q000235:genetics / Q000378:metabolism*; D000597:Amino Acids, Branched-Chain / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003624:Darkness; D004734:Energy Metabolism; D006706:Homeostasis; D008027:Light; D053858:Metabolic Networks and Pathways; D009154:Mutation; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000502:physiology / Q000528:radiation effects
chemical_list: D000597:Amino Acids, Branched-Chain; D029681:Arabidopsis Proteins; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)