PDBsum entry 1oc9

Electron transport

PDB id: 1oc9

Contents

Protein chains

151 a.a. *

Waters ×133

* Residue conservation analysis

PDB id:

1oc9

Name:

Electron transport

Title:

Tryparedoxin ii from c.Fasciculata solved by mr

Structure:

Tryparedoxin ii. Chain: a. Fragment: residues 16-165. Engineered: yes. Tryparedoxin ii. Chain: b. Fragment: residues 16-165. Engineered: yes

Source:

Crithidia fasciculata. Organism_taxid: 5656. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.35Å R-factor: 0.197 R-free: 0.213

Authors:

G.A.Leonard,E.Micossi,W.N.Hunter

Key ref:

M.S.Alphey et al. (2003). Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei: photoreduction of the redox disulfide using synchrotron radiation and evidence for a conformational switch implicated in function. J Biol Chem, 278, 25919-25925. PubMed id: 12707277 DOI: 10.1074/jbc.M301526200

Date:

07-Feb-03 Release date: 20-Mar-03

Protein chains

O77093  (O77093_CRIFA) -  Tryparedoxin II from Crithidia fasciculata

Seq: 165 a.a.

Struc: 151 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1074/jbc.M301526200

J Biol Chem 278:25919-25925 (2003)

PubMed id: 12707277

Tryparedoxins from Crithidia fasciculata and Trypanosoma brucei: photoreduction of the redox disulfide using synchrotron radiation and evidence for a conformational switch implicated in function.

M.S.Alphey, M.Gabrielsen, E.Micossi, G.A.Leonard, S.M.McSweeney, R.B.Ravelli, E.Tetaud, A.H.Fairlamb, C.S.Bond, W.N.Hunter.

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.

Selected figure(s)

Figure 2.
FIG. 2. The structure of tryparedoxin. a, a ribbon diagram depicting the TryX fold, secondary structure assignment, and location of the redox-active disulfide formed between Cys-40 and Cys-43 (yellow sticks). Figs. 2a and 3, 4,5 were prepared with MOLSCRIPT (39) and RASTER3D (40). In b, the amino acid sequence of residues colored red are strictly conserved, and those colored black are similar at scale 7 in the ALSCRIPT program (41). The active site motif WCPPCR is marked with o .

Figure 4.
FIG. 4. The CfTryX1 and CfTryXC43A structures. Stereoview overlay of the active sites of native CfTryX1 (carbon atoms colored green) and CfTryX1C43A (carbon atoms colored magenta), showing the adjustment in position of Ser-36 and Tyr-80 to compensate for the mutation of Cys-43. Dashed lines represent hydrogen bonding interactions.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 25919-25925) copyright 2003.

Figures were selected by the author.