3D21

Crystal structure of a poplar wild-type thioredoxin h, PtTrxh4

Summary for 3D21

• Entry DOI: 10.2210/pdb3d21/pdb
• Related: 3D22
• Descriptor: Thioredoxin H-type (2 entities in total)
• Functional Keywords: thioredoxin h, electron transport, transport, cytoplasm, redox-active center, oxidoreductase
• Biological source: Populus trichocarpa x Populus deltoides (Balm of Gilead)
• Cellular location: Cytoplasm : P85801
• Total number of polymer chains: 2
• Total formula weight: 31333.54

Authors

Koh, C.S.,Didierjean, C.,Corbier, C.,Rouhier, N.,Jacquot, J.P.,Gelhaye, E. (deposition date: 2008-05-07, release date: 2008-07-01, Last modification date: 2024-11-06)

Primary citation

Koh, C.S.,Navrot, N.,Didierjean, C.,Rouhier, N.,Hirasawa, M.,Knaff, D.B.,Wingsle, G.,Samian, R.,Jacquot, J.P.,Corbier, C.,Gelhaye, E.
An Atypical Catalytic Mechanism Involving Three Cysteines of Thioredoxin.
J.Biol.Chem., 283:23062-23072, 2008

PubMed Abstract: 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.

PubMed: 18552403
DOI: 10.1074/jbc.M802093200

Experimental method

X-RAY DIFFRACTION (2.15 Å)