PDBsum entry 3pc6

DNA binding protein

PDB id: 3pc6

Contents

Protein chains

99 a.a.

Waters ×183

PDB id:

3pc6

Name:

DNA binding protein

Title:

X-ray crystal structure of the second xrcc1 brct domain.

Structure:

DNA repair protein xrcc1. Chain: a, b. Fragment: xrcc1 second brct domain (unp residues 534-630). Synonym: x-ray repair cross-complementing protein 1. Engineered: yes

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Gene: xrcc-1, xrcc1. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.182 R-free: 0.227

Authors:

M.J.Cuneo,J.M.Krahn,R.E.London

Key ref:

M.J.Cuneo et al. (2011). The structural basis for partitioning of the XRCC1/DNA ligase III-α BRCT-mediated dimer complexes. Nucleic Acids Res, 39, 7816-7827. PubMed id: 21652643

Date:

21-Oct-10 Release date: 15-Jun-11

Protein chains

Q60596  (XRCC1_MOUSE) -  DNA repair protein XRCC1 from Mus musculus

Seq: 631 a.a.

Struc: 99 a.a.

Nucleic Acids Res 39:7816-7827 (2011)

PubMed id: 21652643

The structural basis for partitioning of the XRCC1/DNA ligase III-α BRCT-mediated dimer complexes.

M.J.Cuneo, S.A.Gabel, J.M.Krahn, M.A.Ricker, R.E.London.

ABSTRACT

The ultimate step common to almost all DNA repair pathways is the ligation of the nicked intermediate to form contiguous double-stranded DNA. In the mammalian nucleotide and base excision repair pathways, the ligation step is carried out by ligase III-α. For efficient ligation, ligase III-α is constitutively bound to the scaffolding protein XRCC1 through interactions between the C-terminal BRCT domains of each protein. Although structural data for the individual domains has been available, no structure of the complex has been determined and several alternative proposals for this interaction have been advanced. Interpretation of the models is complicated by the formation of homodimers that, depending on the model, may either contribute to, or compete with heterodimer formation. We report here the structures of both homodimer complexes as well as the heterodimer complex. Structural characterization of the heterodimer formed from a longer XRCC1 BRCT domain construct, including residues comprising the interdomain linker region, revealed an expanded heterodimer interface with the ligase III-α BRCT domain. This enhanced linker-mediated binding interface plays a significant role in the determination of heterodimer/homodimer selectivity. These data provide fundamental insights into the structural basis of BRCT-mediated dimerization, and resolve questions related to the organization of this important repair complex.