Induction of β‐methylcrotonyl‐coenzyme A carboxylase in higher plant cells during carbohydrate starvation: evidence for a role of MCCase in leucine catabolism

Aubert, S.; Alban, Claude; Bligny, Richard; Douce, Roland

doi:10.1016/0014-5793(96)00244-x

Cited by 42 publications

(42 citation statements)

References 34 publications

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“…These data expand previous studies in soybean and pea, which indicate that MCCase activity is higher in metabolically active organs (42) and increases in response to carbohydrate starvation (41). The data presented herein, in combination with these previous studies (41,42), indicate that changes in MCCase activity are at least partially attributable to changes in MCCase mRNA accumulation.…”

Section: -Methylcrotonyl-coa Carboxylasesupporting

confidence: 88%

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Molecular Characterization of the Non-biotin-containing Subunit of 3-Methylcrotonyl-CoA Carboxylase

McKean¹,

Ke²,

Song³

et al. 2000

Journal of Biological Chemistry

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Section: -Methylcrotonyl-coa Carboxylasesupporting

confidence: 88%

“…We interpret elevated MCCase mRNA levels to reflect higher rates of leucine (1,5,(41)(42)(43) and/or isoprenoid (2,42,44) catabolism. We hypothesize that such increased catabolism is needed to satiate demands for ATP generation, particularly in organs and tissues that are not net photosynthetic.…”

Section: -Methylcrotonyl-coa Carboxylasementioning

confidence: 95%

Molecular Characterization of the Non-biotin-containing Subunit of 3-Methylcrotonyl-CoA Carboxylase

McKean¹,

Ke²,

Song³

et al. 2000

Journal of Biological Chemistry

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“…Ten-gram samples of roots from 3-week-old plants grown in Pi-sufficient conditions (500 mM) were cut into 4-to 5-mm 2 pieces, vacuum-infiltrated in perfusion solution [5 mM glucose, 10 mM KNO 3 , 0.5 mM Ca(NO 3 ) 2 , 1 mM KCl, 0.5 mM MgSO 4 , and 50 mM KH 2 PO 4 at pH 6.0], and placed into a 25-mm glass tube under constant perfusion. In vivo 31 P-NMR spectra were recorded on a spectrometer (AMX 400; Bruker) as described previously (Aubert et al, 1996). ImageJ v1.37 software (http://rsb.info.nih.gov/ij) was used to analyze NMR peak areas.…”

Section: Nmr Analysesmentioning

confidence: 99%

ESCRT-III-Associated Protein ALIX Mediates High-Affinity Phosphate Transporter Trafficking to Maintain Phosphate Homeostasis in Arabidopsis

et al. 2015

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ORCID IDs: 0000-0003-2780-4888 (C.R.); 0000-0002-8800-2400 (V.R.)Prior to the release of their cargoes into the vacuolar lumen, sorting endosomes mature into multivesicular bodies (MVBs) through the action of ENDOSOMAL COMPLEX REQUIRED FOR TRANSPORT (ESCRT) protein complexes. MVB-mediated sorting of high-affinity phosphate transporters (PHT1) to the vacuole limits their plasma membrane levels under phosphatesufficient conditions, a process that allows plants to maintain phosphate homeostasis. Here, we describe ALIX, a cytosolic protein that associates with MVB by interacting with ESCRT-III subunit SNF7 and mediates PHT1;1 trafficking to the vacuole in Arabidopsis thaliana. We show that the partial loss-of-function mutant alix-1 displays reduced vacuolar degradation of PHT1;1. ALIX derivatives containing the alix-1 mutation showed reduced interaction with SNF7, providing a simple molecular explanation for impaired cargo trafficking in alix-1 mutants. In fact, the alix-1 mutation also hampered vacuolar sorting of the brassinosteroid receptor BRI1. We also show that alix-1 displays altered vacuole morphogenesis, implying a new role for ALIX proteins in vacuolar biogenesis, likely acting as part of ESCRT-III complexes. In line with a presumed broad target spectrum, the alix-1 mutation is pleiotropic, leading to reduced plant growth and late flowering, with stronger alix mutations being lethal, indicating that ALIX participates in diverse processes in plants essential for their life. INTRODUCTIONTrafficking of cargo proteins coming from the plasma membrane (PM) or the Golgi apparatus (GA) to the vacuole occurs through multivesicular bodies (MVBs) (Winter and Hauser, 2006). These organelles, also termed late endosomes or prevacuolar compartments (PVCs), contain internal vesicles that will be delivered, together with their cargoes, into the lumen of vacuoles/lysosomes upon MVB fusion with the tonoplast (Winter and Hauser, 2006). This process plays a central role in controlling the reutilization, storage, or degradation of membrane components and thus regulates fundamental biological processes including membrane turnover, defense against pathogens, development, hormone transport, nutrient uptake, and cell signaling. In the case of membrane-associated regulatory proteins, the MVB route allows modulation of their function by regulating their abundance at the PM and in other vesicular compartments (e.g., endosomes).The sorting of most integral membrane proteins into intraluminal vesicles (ILVs) is dependent on the attachment of ubiquitin to their cytosolic domains, although ubiquitin-independent sorting mechanisms also exist (McNatt et al., 2007). Selective packaging of protein cargoes into ILVs of MVB is mediated by ESCRT (ENDOSOMAL SORTING COMPLEXES REQUIRED FOR TRANSPORT) protein complexes (Conibear, 2002;Winter and Hauser, 2006;Nickerson et al., 2007;Henne et al., 2011). The latter consist of several cytosolic proteins of the VPS-E (class E Vacuolar Protein Sorting) class that are organized into five complexes: ESCRT-0...

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“…The catabolism of these amino acids generally involves compounds such as acetoacetate and succinyl-CoA, which enter the Krebs cycle (3). Aubert et al (13) found that leucine, after asparagine, was the second most abundant amino acid that transiently accumulated in sycamore (Acer pseudoplatanus L.) cultured cells during carbohydrate starvation. The end product derived from leucine was thought to be used in place of sugars to fuel respiration in the mitochondria (13).…”

Section: Discussionmentioning

confidence: 99%

“…Aubert et al (13) found that leucine, after asparagine, was the second most abundant amino acid that transiently accumulated in sycamore (Acer pseudoplatanus L.) cultured cells during carbohydrate starvation. The end product derived from leucine was thought to be used in place of sugars to fuel respiration in the mitochondria (13). Valine and isoleucine were also massively accumulated in sugar-starved sycamore cells (13).…”

Section: Discussionmentioning

confidence: 99%

Isolation and Characterization of cDNA Clones for the E1β and E2 Subunits of the Branched-chain α-Ketoacid Dehydrogenase Complex in Arabidopsis

Fujiki

Sato

Ito

et al. 2000

Journal of Biological Chemistry

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Branched-chain ␣-ketoacid dehydrogenase (BCKDH) has been known in mammals to be a key enzyme of the catabolic pathway of branched-chain amino acids. We have isolated two cDNA clones encoding the E1␤ and E2 subunits of BCKDH, respectively, from Arabidopsis thaliana. Proteins encoded in these cDNA sequences had putative mitochondrial targeting sequences and conserved domains reported for their mammalian counterparts. Northern blot and immunoblot analyses showed that transcripts from the respective genes and E2 protein markedly accumulated in leaves kept in the dark. We found that the activity of BCKDH in the leaf extracts also increased when plants were placed in the dark. Addition of sucrose to detached leaves inhibited the accumulation of transcripts, whereas application of a photosynthesis inhibitor strongly induced the expression of these genes even under light illumination. These observations indicate that the cellular sugar level is likely responsible for the dark-induced expression of these genes. The transcript levels of these genes were also high in senescing leaves, in which photosynthetic activity is low and free amino acids from degraded protein are likely to serve as an alternative energy source.The mammalian branched-chain ␣-ketoacid dehydrogenase (BCKDH) 1 is a mitochondrial multienzyme complex that is composed of three subunits carrying different enzymatic activities: branched-chain ␣-ketoacid decarboxylase (E1; EC 1.2.4.4), dihydrolipoyl transacylase (E2; no EC number), and dihydrolipoamide dehydrogenase (E3; EC 1.8.1.4). The E1 subunit is further composed of two E1␣ and two E1␤ subunits. This enzyme complex also contains two specific regulatory enzymes, a kinase and a phosphatase (1). E1 catalyzes the oxidative decarboxylation of branched-chain ␣-keto acids, which are derived from branched-chain amino acids by transamination. E2 catalyzes the transfer of the acyl group from the lipoyl moiety to coenzyme A. E3 is a flavoprotein and reoxidizes the reduced lipoyl sulfur residues of the E2 subunit (2).BCKDH in mammals is thought to be a key enzyme in the catabolism of the branched-chain amino acids, i.e. valine, leucine, and isoleucine. As end products, leucine is converted to acetyl-CoA and acetoacetate, valine to succinyl-CoA, and isoleucine to succinyl-CoA and acetyl-CoA (3). Through this pathway, these amino acids serve as substrates for energy production via acetoacetate and succinyl-CoA. It has been firmly established that nutritional conditions play an important role in modulating the activity of BCKDH through a phosphorylation-dephosphorylation mechanism (4). From this point of view, BCKDH is critically important in the pathway for energy utilization, rather than being merely a system for the catabolism of a small group of amino acids.BCKDH has been extensively studied in mammals because defects in the genes for this enzyme cause maple syrup urine disease, an inborn disorder of metabolism in humans (3). In the plant kingdom, however, we have come across only one case reporting the detection...

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Induction of β‐methylcrotonyl‐coenzyme A carboxylase in higher plant cells during carbohydrate starvation: evidence for a role of MCCase in leucine catabolism

Cited by 42 publications

References 34 publications

Molecular Characterization of the Non-biotin-containing Subunit of 3-Methylcrotonyl-CoA Carboxylase

Molecular Characterization of the Non-biotin-containing Subunit of 3-Methylcrotonyl-CoA Carboxylase

ESCRT-III-Associated Protein ALIX Mediates High-Affinity Phosphate Transporter Trafficking to Maintain Phosphate Homeostasis in Arabidopsis

Isolation and Characterization of cDNA Clones for the E1β and E2 Subunits of the Branched-chain α-Ketoacid Dehydrogenase Complex in Arabidopsis

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