Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei
Abstract
Tryparedoxin (TryX) is a member of the thioredoxin (TrX) fold family involved in the regulation of oxidative stress in parasitic trypanosomatids. Like TrX, TryX carries a characteristic Trp-Cys-Xaa-Xaa-Cys motif, which positions a redox-active disulfide underneath a tryptophan lid. We report the structure of a Crithidia fasciculata tryparedoxin isoform (CfTryX2) in two crystal forms and compare them with structures determined previously. Efforts to chemically generate crystals of reduced TryX1 were unsuccessful, and we carried out a novel experiment to break the redox-active disulfide, formed between Cys-40 and Cys-43, utilizing the intense x-radiation from a third generation synchrotron undulator beamline. A time course study of the S-S bond cleavage is reported with the structure of a TryX1 C43A mutant as the control. When freed from the constraints of a disulfide link to Cys-43, Cys-40 pivots to become slightly more solvent-accessible. In addition, we have determined the structure of Trypanosoma brucei TryX, which, influenced by the molecular packing in the crystal lattice, displays a significantly different orientation of the active site tryptophan lid. This structural change may be of functional significance when TryX interacts with tryparedoxin peroxidase, the final protein in the trypanothione-dependent peroxidase pathway. Comparisons with chloroplast TrX and its substrate fructose 1,6-bisphosphate phosphatase suggest that this movement may represent a general feature of redox regulation in the trypanothione and thioredoxin peroxidase pathways.
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BibTeX
@article{alphey2026tryparedoxins,
title = {{Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei}},
author = {Magnus Alphey and Mads Gabrielsen and Elena Micossi and Gordon Leonard and Sean Mcsweeney and Raimond B.G. Ravelli and Emmanuel Tetaud and Alan Fairlamb and Charles Bond and William Hunter},
journal = {Journal of Biological Chemistry},
year = {2026},
month = sep,
doi = {10.1074/jbc.m301526200},
url = {https://hal.science/hal-05753745v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei
AU - Magnus Alphey
AU - Mads Gabrielsen
AU - Elena Micossi
AU - Gordon Leonard
AU - Sean Mcsweeney
AU - Raimond B.G. Ravelli
AU - Emmanuel Tetaud
AU - Alan Fairlamb
AU - Charles Bond
AU - William Hunter
PY - 2026
DA - 2026/09/17
JO - Journal of Biological Chemistry
DO - 10.1074/jbc.m301526200
UR - https://hal.science/hal-05753745v1
AB - Tryparedoxin (TryX) is a member of the thioredoxin (TrX) fold family involved in the regulation of oxidative stress in parasitic trypanosomatids. Like TrX, TryX carries a characteristic Trp-Cys-Xaa-Xaa-Cys motif, which positions a redox-active disulfide underneath a tryptophan lid. We report the structure of a Crithidia fasciculata tryparedoxin isoform (CfTryX2) in two crystal forms and compare them with structures determined previously. Efforts to chemically generate crystals of reduced TryX1 were unsuccessful, and we carried out a novel experiment to break the redox-active disulfide, formed between Cys-40 and Cys-43, utilizing the intense x-radiation from a third generation synchrotron undulator beamline. A time course study of the S-S bond cleavage is reported with the structure of a TryX1 C43A mutant as the control. When freed from the constraints of a disulfide link to Cys-43, Cys-40 pivots to become slightly more solvent-accessible. In addition, we have determined the structure of Trypanosoma brucei TryX, which, influenced by the molecular packing in the crystal lattice, displays a significantly different orientation of the active site tryptophan lid. This structural change may be of functional significance when TryX interacts with tryparedoxin peroxidase, the final protein in the trypanothione-dependent peroxidase pathway. Comparisons with chloroplast TrX and its substrate fructose 1,6-bisphosphate phosphatase suggest that this movement may represent a general feature of redox regulation in the trypanothione and thioredoxin peroxidase pathways.
SN - 0021-9258
SN - 1083-351X
ER -