PDBsum entry 2oa8

Hydrolase/DNA

PDB id: 2oa8

Contents

Protein chains

220 a.a. *

DNA/RNA

Metals

_CA ×4

Waters ×288

* Residue conservation analysis

PDB id:

2oa8

Name:

Hydrolase/DNA

Title:

Crystal structure of mtrex1 with ssdna

Structure:

5'-d( Gp Ap Cp G)-3'. Chain: c, d. Engineered: yes. Three prime repair exonuclease 1. Chain: a, b. Fragment: n-terminal fragment, residues 5-234. Synonym: 3'-5' exonuclease trex1. Engineered: yes

Source:

Synthetic: yes. Mus musculus. House mouse. Organism_taxid: 10090. Gene: trex1. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Resolution:

2.10Å R-factor: 0.195 R-free: 0.259

Authors:

U.De Silva,T.Hollis

Key ref:

U.de Silva et al. (2007). The crystal structure of TREX1 explains the 3' nucleotide specificity and reveals a polyproline II helix for protein partnering. J Biol Chem, 282, 10537-10543. PubMed id: 17293595 DOI: 10.1074/jbc.M700039200

Date:

15-Dec-06 Release date: 20-Feb-07

Protein chains

Q91XB0  (TREX1_MOUSE) -  Three-prime repair exonuclease 1 from Mus musculus

Seq: 314 a.a.

Struc: 220 a.a.

DNA/RNA chains

G-A-C-G 4 bases

G-A-C-G 4 bases

Enzyme reactions

• Enzyme class: 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.

DOI no: 10.1074/jbc.M700039200

J Biol Chem 282:10537-10543 (2007)

PubMed id: 17293595

The crystal structure of TREX1 explains the 3' nucleotide specificity and reveals a polyproline II helix for protein partnering.

U.de Silva, S.Choudhury, S.L.Bailey, S.Harvey, F.W.Perrino, T.Hollis.

ABSTRACT

The TREX1 enzyme processes DNA ends as the major 3' --> 5' exonuclease activity in human cells. Mutations in the TREX1 gene are an underlying cause of the neurological brain disease Aicardi-Goutières syndrome implicating TREX1 dysfunction in an aberrant immune response. TREX1 action during apoptosis likely prevents autoimmune reaction to DNA that would otherwise persist. To understand the impact of TREX1 mutations identified in patients with Aicardi-Goutières syndrome on structure and activity we determined the x-ray crystal structure of the dimeric mouse TREX1 protein in substrate and product complexes containing single-stranded DNA and deoxyadenosine monophosphate, respectively. The structures show the specific interactions between the bound nucleotides and the residues lining the binding pocket of the 3' terminal nucleotide within the enzyme active site that account for specificity, and provide the molecular basis for understanding mutations that lead to disease. Three mutant forms of TREX1 protein identified in patients with Aicardi-Goutières syndrome were prepared and the measured activities show that these specific mutations reduce enzyme activity by 4-35,000-fold. The structure also reveals an 8-amino acid polyproline II helix within the TREX1 enzyme that suggests a mechanism for interactions of this exonuclease with other protein complexes.

Selected figure(s)

Figure 1.
FIGURE 1. The TREX1 dimer in complex with ssDNA. The TREX1 exonuclease dimerizes about a 2-fold axis perpendicular to the -strands (monomers shown in blue and green). This interaction creates an extended anti-parallel -sheet through the core of the dimer and places the two active sites on opposite outer edges. The complex contains ssDNA (shown as sticks) and Ca^2+ (shown as red spheres) bound in both of the active sites.

Figure 4.
FIGURE 4. TREX1 structure reveals PPII helix. a, the non-repetitive proline-rich region within TREX1 forms a PPII. The PPII helix, made up of residues 54–62, has a tight, 3-sided, left-handed secondary structure. PPII helices often function as interaction motifs with other proteins containing SH3, WW, or EVH1 domains. b, location of PPII helices (shown in red) within the TREX1 dimer. The positioning on opposite outer edges of the same face of the dimer might play a key role in TREX1 protein interactions by allowing for simultaneous binding of multiple interaction domains to the dimer.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 10537-10543) copyright 2007.

Figures were selected by an automated process.