Glutathionylation of cytosolic glyceraldehyde-3-phosphate dehydrogenase from the model plant Arabidopsis thaliana is reversed by both glutaredoxins and thioredoxins in vitro.

Biochem J 2012 Aug;445(3):337-47

Laboratory of Molecular Plant Physiology, Department of Experimental Evolutionary Biology, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy.

Plants contain both cytosolic and chloroplastic GAPDHs (glyceraldehyde-3-phosphate dehydrogenases). In Arabidopsis thaliana, cytosolic GAPDH is involved in the glycolytic pathway and is represented by two differentially expressed isoforms (GapC1 and GapC2) that are 98% identical in amino acid sequence. In the present study we show that GapC1 is a phosphorylating NAD-specific GAPDH with enzymatic activity strictly dependent on Cys(149). Catalytic Cys(149) is the only solvent-exposed cysteine of the protein and its thiol is relatively acidic (pK(a)=5.7). This property makes GapC1 sensitive to oxidation by H(2)O(2), which appears to inhibit enzyme activity by converting the thiolate of Cys(149) (-S-) into irreversible oxidized forms (-SO(2)(-) and -SO(3)(-)) via a labile sulfenate intermediate (-SO(-)). GSH (reduced glutathione) prevents this irreversible process by reacting with Cys(149) sulfenates to give rise to a mixed disulfide (Cys(149)-SSG), as demonstrated by both MS and biotinylated GSH. Glutathionylated GapC1 can be fully reactivated either by cytosolic glutaredoxin, via a GSH-dependent monothiol mechanism, or, less efficiently, by cytosolic thioredoxins physiologically reduced by NADPH:thioredoxin reductase. The potential relevance of these findings is discussed in the light of the multiple functions of GAPDH in eukaryotic cells (e.g. glycolysis, control of gene expression and apoptosis) that appear to be influenced by the redox state of the catalytic Cys(149).

Download full-text PDF

Source
http://dx.doi.org/10.1042/BJ20120505DOI Listing
August 2012
44 Reads

Publication Analysis

Top Keywords

catalytic cys149
8
arabidopsis thaliana
8
cys149
5
findings discussed
4
solvent-exposed cysteine
4
cys149 solvent-exposed
4
reduced glutathione
4
cys149 catalytic
4
study gapc1
4
glutaredoxin gsh-dependent
4
cysteine protein
4
potential relevance
4
acidic pka=57
4
thiol acidic
4
gsh reduced
4
relevance findings
4
protein thiol
4
glutathione prevents
4
dependent cys149
4
gapdh enzymatic
4

References

(Supplied by CrossRef)

Gao X et al.
Mol. Plant 2009

Similar Publications