Sammanfattning

Unlike other thioredoxins h characterized so far, a poplar thioredoxin of the h type, PtTrxh4, is reduced by glutathione and glutaredoxin (Grx) but not NADPH: thioredoxin reductase (NTR). PtTrxh4 contains three cysteines: one localized in an N-terminal extension (Cys(4)) and two (Cys(58) and Cys(61)) in the classical thioredoxin active site ( (57)WCGPC(61)). The property of a mutant in which Cys(58) was replaced by serine demonstrates that it is responsible for the initial nucleophilic attack during the catalytic cycle. The observation that the C4S mutant is inactive in the presence of Grx but fully active when dithiothreitol is used as a reductant indicates that Cys(4) is required for the regeneration of PtTrxh4 by Grx. Biochemical and x-ray crystallographic studies indicate that two intramolecular disulfide bonds involving Cys(58) can be formed, linking it to either Cys(61) or Cys(4). We propose thus a four-step disulfide cascade mechanism involving the transient glutathionylation of Cys(4) to convert this atypical thioredoxin h back to its active reduced form.

Publicerad i

Journal of Biological Chemistry
2008, Volym: 283, nummer: 34, sidor: 23062-23072
Utgivare: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

SLU författare

• Wingsle, Gunnar

  • Institutionen för skoglig genetik och växtfysiologi, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Biokemi och molekylärbiologi


Publikationens identifierare

DOI: https://doi.org/10.1074/jbc.M802093200

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/78183