Dealing with the sulfur part of cysteine: four enzymatic steps degrade l-cysteine to pyruvate and thiosulfate in Arabidopsis mitochondria.
Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from Arabidopsis thaliana T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Saskia
S
Höfler
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Christin
C
Lorenz
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Tjorven
T
Busch
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Mascha
M
Brinkkötter
Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
Takayuki
T
Tohge
Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
Alisdair R
AR
Fernie
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Hans-Peter
HP
Braun
Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
Tatjana M
TM
Hildebrandt
D000596:Amino Acids / Q000378:metabolism; D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D004734:Energy Metabolism; D005978:Glutathione / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D008928:Mitochondria / Q000378:metabolism; D016254:Mutagenesis, Insertional; D019289:Pyruvic Acid / Q000378:metabolism; D012639:Seeds / Q000196:embryology / Q000201:enzymology / Q000235:genetics; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism; D013466:Sulfurtransferases / Q000235:genetics / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism
D000596:Amino Acids; D029681:Arabidopsis Proteins; D013438:Sulfhydryl Compounds; D013885:Thiosulfates; C008366:3-mercaptopyruvic acid; D013455:Sulfur; D019289:Pyruvic Acid; D049308:Dioxygenases; C000593849:ETHE1 protein, Arabidopsis; D013466:Sulfurtransferases; C557797:sulfurtransferase 1, Arabidopsis; D005978:Glutathione; D003545:Cysteine