The High Resolution Crystal Structure of Recombinant Crithidia fasciculata Tryparedoxin-I
Abstract
Tryparedoxin-I is a recently discovered thiol-disulfide oxidoreductase involved in the regulation of oxidative stress in parasitic trypanosomatids. The crystal structure of recombinant Crithidia fasciculata tryparedoxin-I in the oxidized state has been determined using multi-wavelength anomalous dispersion methods applied to a selenomethionyl derivative. The model comprises residues 3 to 145 with 236 water molecules and has been refined using all data between a 19- and 1.4-A resolution to an R-factor and R-free of 19.1 and 22.3%, respectively. Despite sharing only about 20% sequence identity, tryparedoxin-I presents a five-stranded twisted beta-sheet and two elements of helical structure in the same type of fold as displayed by thioredoxin, the archetypal thiol-disulfide oxidoreductase. However, the relationship of secondary structure with the linear amino acid sequences is different for each protein, producing a distinctive topology. The beta-sheet core is extended in the trypanosomatid protein with an N-terminal beta-hairpin. There are also differences in the content and orientation of helical elements of secondary structure positioned at the surface of the proteins, which leads to different shapes and charge distributions between human thioredoxin and tryparedoxin-I. A right-handed redox-active disulfide is formed between Cys-40 and Cys-43 at the N-terminal region of a distorted alpha-helix (alpha1). Cys-40 is solvent-accessible, and Cys-43 is positioned in a hydrophilic cavity. Three C-H...O hydrogen bonds donated from two proline residues serve to stabilize the disulfide-carrying helix and support the correct alignment of active site residues. The accurate model for tryparedoxin-I allows for comparisons with the family of thiol-disulfide oxidoreductases and provides a template for the discovery or design of selective inhibitors of hydroperoxide metabolism in trypanosomes. Such inhibitors are sought as potential therapies against a range of human pathogens.
Related
- Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei
- RNA engineering approaches to aid high-resolution structure determination of medium- to large-sized RNAs
- Deep Learning for Protein Secondary-Structure Segmentation in Intermediate-Resolution Cryo-EM Maps: A Resolution-Stratified Benchmark Dataset and Controlled Evaluation
- CryoFAST: A Fab-Aided Cryo-EM Workflow for High-Resolution Structure Determination of Sub-50-kDa Protein Targets
- Understanding the strengths and limitations of recombinant protein studies
BibTeX
@article{alphey2026high,
title = {{The High Resolution Crystal Structure of Recombinant Crithidia fasciculata Tryparedoxin-I}},
author = {Magnus Alphey and Gordon Leonard and David Gourley and Emmanuel Tetaud and Alan Fairlamb and William Hunter},
journal = {Journal of Biological Chemistry},
year = {2026},
month = sep,
doi = {10.1074/jbc.274.36.25613},
url = {https://hal.science/hal-05753762v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - The High Resolution Crystal Structure of Recombinant Crithidia fasciculata Tryparedoxin-I
AU - Magnus Alphey
AU - Gordon Leonard
AU - David Gourley
AU - Emmanuel Tetaud
AU - Alan Fairlamb
AU - William Hunter
PY - 2026
DA - 2026/09/17
JO - Journal of Biological Chemistry
DO - 10.1074/jbc.274.36.25613
UR - https://hal.science/hal-05753762v1
AB - Tryparedoxin-I is a recently discovered thiol-disulfide oxidoreductase involved in the regulation of oxidative stress in parasitic trypanosomatids. The crystal structure of recombinant Crithidia fasciculata tryparedoxin-I in the oxidized state has been determined using multi-wavelength anomalous dispersion methods applied to a selenomethionyl derivative. The model comprises residues 3 to 145 with 236 water molecules and has been refined using all data between a 19- and 1.4-A resolution to an R-factor and R-free of 19.1 and 22.3%, respectively. Despite sharing only about 20% sequence identity, tryparedoxin-I presents a five-stranded twisted beta-sheet and two elements of helical structure in the same type of fold as displayed by thioredoxin, the archetypal thiol-disulfide oxidoreductase. However, the relationship of secondary structure with the linear amino acid sequences is different for each protein, producing a distinctive topology. The beta-sheet core is extended in the trypanosomatid protein with an N-terminal beta-hairpin. There are also differences in the content and orientation of helical elements of secondary structure positioned at the surface of the proteins, which leads to different shapes and charge distributions between human thioredoxin and tryparedoxin-I. A right-handed redox-active disulfide is formed between Cys-40 and Cys-43 at the N-terminal region of a distorted alpha-helix (alpha1). Cys-40 is solvent-accessible, and Cys-43 is positioned in a hydrophilic cavity. Three C-H...O hydrogen bonds donated from two proline residues serve to stabilize the disulfide-carrying helix and support the correct alignment of active site residues. The accurate model for tryparedoxin-I allows for comparisons with the family of thiol-disulfide oxidoreductases and provides a template for the discovery or design of selective inhibitors of hydroperoxide metabolism in trypanosomes. Such inhibitors are sought as potential therapies against a range of human pathogens.
SN - 0021-9258
SN - 1083-351X
ER -