PDBsum entry 1cqh

Complex (electron transport/peptide)

PDB id: 1cqh

Contents

Protein chains

105 a.a. *

13 a.a. *

* Residue conservation analysis

PDB id:

1cqh

Name:

Complex (electron transport/peptide)

Title:

High resolution solution nmr structure of mixed disulfide intermediate between human thioredoxin (c35a, c62a, c69a, c73a) mutant and a 13 residue peptide comprising its target site in human ref-1 (residues 59-71 of the p50 subunit of nfkb), nmr, minimized average structure

Structure:

Thioredoxin. Chain: a. Engineered: yes. Mutation: yes. Ref-1 peptide. Chain: b. Fragment: residues 59 - 71 of the p50 subunit of nfkb. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: potential.

NMR struc:

1 models

Authors:

G.M.Clore,J.Qin,A.M.Gronenborn

Key ref:

J.Qin et al. (1996). The solution structure of human thioredoxin complexed with its target from Ref-1 reveals peptide chain reversal. Structure, 4, 613-620. PubMed id: 8736558 DOI: 10.1016/S0969-2126(96)00065-2

Date:

02-Apr-96 Release date: 01-Aug-96

Protein chain

P10599  (THIO_HUMAN) -  Thioredoxin from Homo sapiens

Seq: 105 a.a.

Struc: 105 a.a.*

Protein chain

P27695  (APEX1_HUMAN) -  DNA repair nuclease/redox regulator APEX1 from Homo sapiens

Seq: 318 a.a.

Struc: 13 a.a.

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class 1: Chain B: E.C.3.1.11.2 - exodeoxyribonuclease Iii.
• Reaction: Degradation of double-stranded DNA. It acts progressively in a 3'- to 5'-direction, releasing nucleoside 5'-phosphates.
• Enzyme class 2: Chain B: E.C.3.1.21.- - ?????

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

DOI no: 10.1016/S0969-2126(96)00065-2

Structure 4:613-620 (1996)

PubMed id: 8736558

The solution structure of human thioredoxin complexed with its target from Ref-1 reveals peptide chain reversal.

J.Qin, G.M.Clore, W.P.Kennedy, J.Kuszewski, A.M.Gronenborn.

ABSTRACT

BACKGROUND: Human thioredoxin (hTRX) is a 12 kDa cellular redox protein that has been shown to play an important role in the activation of a number of transcriptional and translational regulators via a thiol-redox mechanism. This activity may be direct or indirect via another redox protein known as Ref-1. The structure of a complex of hTRX with a peptide comprising its target from the transcription factor NF kappa B has previously been solved. To further extend our knowledge of the recognition by and interaction of hTRX with its various targets, we have studied a complex between hTRX and a Ref-1 peptide. This complex represents a kinetically stable mixed disulfide intermediate along the reaction pathway. RESULTS: Using multidimensional heteronuclear edited and filtered NMR spectroscopy, we have solved the solution structure of a complex between hTRX and a 13-residue peptide comprising residues 59-71 of Ref-1. The Ref-1 peptide is located in a crescent-shaped groove on the surface of hTRX, the groove being formed by residues in the active-site loop (residues 32-36), helix 3, beta strands 3 and 5, and the loop between beta strands 3 and 4. The complex is stabilized by numerous hydrogen-bonding and hydrophobic interactions that involve residues 61-69 of the peptide and confer substrate specificity. CONCLUSIONS: The orientation of the Ref-1 peptide in the hTRX-Ref-1 complex is opposite to that found in the previously solved complex of hTRX with the target peptide from the transcription factor NF kappa B. Orientation is determined by three discriminating interactions involving the nature of the residues at the P-2' P-4 and P-5 binding positions. (P0 defines the active cysteine of the peptide, Cys65 for Ref-1 and Cys62 for NF kappa B. Positive and negative numbers indicate residues N-terminal and C-terminal to this residue, respectively, and vice versa for NF kappa B as it binds in the opposite orientation.) The environment surrounding the reactive Cys32 of hTRX, as well as the packing of the P+3 to P-4 residues are essentially the same in the two complexes, despite the opposing orientation of the peptide chains. This versatility in substrate recognition permits hTRX to act as a wide-ranging redox regulator for the cell.

Selected figure(s)

Figure 3.
Figure 3. Stereoview showing the interactions between the Ref-1 peptide and hTRX. The backbones (N, Cα, C) of hTRX and the Ref-1 peptide are shown in blue and red, respectively; the side chains of hTRX and the Ref-1 peptide at the interface of the complex are shown in magenta and green, respectively; and the disulfide bond between Cys32 of hTRX and cys62 of the Ref-1 peptide is shown in yellow. Figure 3. Stereoview showing the interactions between the Ref-1 peptide and hTRX. The backbones (N, Cα, C) of hTRX and the Ref-1 peptide are shown in blue and red, respectively; the side chains of hTRX and the Ref-1 peptide at the interface of the complex are shown in magenta and green, respectively; and the disulfide bond between Cys32 of hTRX and cys62 of the Ref-1 peptide is shown in yellow. (The figure was generated with the program VISP [3][44].)

Figure 5.
Figure 5. Schematic summary of the interactions observed in the hTRX–Ref-1 and hTRX–NFκB complexes. (a) All interactions with the exception of those involving backbone–backbone hydrogen bonds: hydrophobic, hydrogen-bonding and salt bridge interactions are represented by continuous (—), long dashed (– – –) and short dashed (- - -) lines, respectively. (b) Backbone–backbone hydrogen bonds. Figure 5. Schematic summary of the interactions observed in the hTRX–Ref-1 and hTRX–NFκB complexes. (a) All interactions with the exception of those involving backbone–backbone hydrogen bonds: hydrophobic, hydrogen-bonding and salt bridge interactions are represented by continuous (—), long dashed (– – –) and short dashed (- - -) lines, respectively. (b) Backbone–backbone hydrogen bonds.

The above figures are reprinted by permission from Cell Press: Structure (1996, 4, 613-620) copyright 1996.

Figures were selected by an automated process.