Plasticity of the mitoproteome to nitrogen sources (nitrate and ammonium) in Chlamydomonas reinhardtii: the logic of Aox1 gene localization.
Nitrate and ammonium constitute primary inorganic nitrogen sources that can be incorporated into carbon skeletons in photosynthetic eukaryotes. In Chlamydomonas, previous studies and the present one showed that the mitochondrial AOX is up-regulated in nitrate-grown cells in comparison with ammonium-grown cells. In this work, we have performed a comparative proteomic analysis of the soluble mitochondrial proteome of Chlamydomonas cells growth either on nitrate or ammonium. Our results highlight important proteomics modifications mostly related to primary metabolism in cells grown on nitrate. We could note an up-regulation of some TCA cycle enzymes and a down-regulation of cytochrome c1 together with an up-regulation of l-arginine and purine catabolism enzymes and of ROS scavenging systems. Hence, in nitrate-grown cells, AOX may play a dual role: (1) lowering the ubiquinone pool reduction level and (2) permitting the export of mitochondrial reducing power under the form of malate for nitrate and nitrite reduction. This role of AOX in the mitochondrial plasticity makes logical the localization of Aox1 in a nitrate assimilation gene cluster.
Gérin
Stéphanie
S
Laboratory of bioenergetics and cellular physiology, B6, Allée de la Chimie 3, 4000 Liège, Belgium.
Mathy
Grégory
G
Blomme
Arnaud
A
Franck
Fabrice
F
Sluse
Francis E
FE
D000596:Amino Acids / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism*; D002952:Citric Acid Cycle; D004579:Electron Transport; D016166:Free Radical Scavengers / Q000378:metabolism; D017343:Genes, Plant; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D008954:Models, Biological; D005810:Multigene Family; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000096:biosynthesis; D020543:Proteome / Q000378:metabolism; D011685:Purine Nucleotides / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D000099188:Alternative Oxidase
D000596:Amino Acids; D016166:Free Radical Scavengers; D024101:Mitochondrial Proteins; D009566:Nitrates; D009573:Nitrites; D009584:Nitrogen; D010088:Oxidoreductases; D010940:Plant Proteins; D020543:Proteome; D011685:Purine Nucleotides; D000644:Quaternary Ammonium Compounds; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D000099188:Alternative Oxidase