Characterization of an Arabidopsis thaliana mutant lacking a cytosolic non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase.
Non-phosphorylating glyceraldehyde- 3-phosphate dehydrogenase (NP-GAPDH) is a conserved cytosolic protein found in higher plants. In photosynthetic cells, the enzyme is involved in a shuttle transfer mechanism to export NADPH from the chloroplast to the cytosol. To investigate the role of this enzyme in plant tissues, we characterized a mutant from Arabidopsis thaliana having an insertion at the NP-GAPDH gene locus. The homozygous mutant was determined to be null respect to NP-GAPDH, as it exhibited undetectable levels of both transcription of NP-GAPDH mRNA, protein expression and enzyme activity. Transcriptome analysis demonstrated that the insertion mutant plant shows altered expression of several enzymes involved in carbohydrate metabolism. Significantly, cytosolic phosphorylating (NAD-dependent) glyceraldehyde-3-phosphate dehydrogenase mRNA levels are induced in the mutant, which correlates with an increase in enzyme activity. mRNA levels and enzymatic activity of glucose-6-phosphate dehydrogenase were also elevated, correlating with an increase in NADPH concentration. Moreover, increased ROS levels were measured in the mutant plants. Down-regulation of several glycolytic and photosynthetic genes suggests that NP-GAPDH is important for the efficiency of both metabolic processes. The results presented demonstrate that NP-GAPDH has a relevant role in plant growth and development.
Rius
Sebastián P
SP
IIB-INTECH, UNSAM-CONICET, CC 164 (7130), Chascomús, Argentina.
Casati
Paula
P
Iglesias
Alberto A
AA
Gomez-Casati
Diego F
DF
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000235:genetics* / Q000378:metabolism; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000235:genetics / Q000378:metabolism; D006019:Glycolysis / Q000235:genetics; D008856:Microscopy, Fluorescence; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics*; D009249:NADP / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013481:Superoxides; D002734:Chlorophyll; D002245:Carbon Dioxide; D009249:NADP; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)