PDBsum entry 5ekf

Protein binding

PDB id: 5ekf

Contents

Protein chain

425 a.a.

Ligands

SER-LEU-LYS-ARG-LYS-ARG

SER-SER-SER-LEU-LYS-ARG-LYS-ARG-LEU-SER

Waters ×189

PDB id:

5ekf

Name:

Protein binding

Title:

Crystallization and x-ray diffraction data collection of importin- alpha from mus musculus complexed with a xpg nls peptide, fragment 1

Structure:

DNA repair protein complementing xp-g cells. Chain: b, c. Fragment: unp residues 1054-1077. Synonym: DNA excision repair protein ercc-5,xeroderma pigmentosum group g-complementing protein. Engineered: yes. Importin subunit alpha-1. Chain: a. Fragment: unp residues 70-529.

Source:

Synthetic: yes. Homo sapiens. Human. Organism_taxid: 9606. Mus musculus. Mouse. Organism_taxid: 10090. Gene: kpna2, rch1. Expressed in: escherichia coli.

Resolution:

2.00Å R-factor: 0.172 R-free: 0.192

Authors:

A.C.Barros,A.A.S.Takeda,M.R.M.Fontes

Key ref:

A.C.Barros et al. (2016). Structural and Calorimetric Studies Demonstrate that Xeroderma Pigmentosum Type G (XPG) Can Be Imported to the Nucleus by a Classical Nuclear Import Pathway via a Monopartite NLS Sequence. J Mol Biol, 428, 2120-2131. PubMed id: 26812207 DOI: 10.1016/j.jmb.2016.01.019

Date:

03-Nov-15 Release date: 10-Feb-16

Protein chain

P52293  (IMA1_MOUSE) -  Importin subunit alpha-1 from Mus musculus

Seq: 529 a.a.

Struc: 425 a.a.

DOI no: 10.1016/j.jmb.2016.01.019

J Mol Biol 428:2120-2131 (2016)

PubMed id: 26812207

Structural and Calorimetric Studies Demonstrate that Xeroderma Pigmentosum Type G (XPG) Can Be Imported to the Nucleus by a Classical Nuclear Import Pathway via a Monopartite NLS Sequence.

A.C.Barros, A.A.Takeda, T.R.Dreyer, A.Velazquez-Campoy, B.Kobe, M.R.Fontes.

ABSTRACT

Xeroderma pigmentosum type G (XPG) proteins are involved in DNA lesion recognition and promotion of nucleotide excision repair. Specific mutations in these proteins may lead to Cockayne syndrome, in which the patients may display severe developmental retardation and neurological abnormalities. No structural information is available for their spacer region or the C-terminal domain, which are important, respectively, for specific nucleotide excision repair activity and substrate specificity, as well as nuclear translocation. Immunofluorescence studies suggested two specific regions of the XPG C-terminus as potential bipartite nuclear localization sequences, which would be responsible for its translocation to the nucleus by the classical nuclear import pathway mediated by the importin-α (Impα). Thus, in order to test these hypotheses and gain insight into the structural basis for the nuclear import process for the XPG protein, we solved the crystal structures of complexes formed by the Impα and peptides corresponding to both putative nuclear localization signal (NLS) sequences (XPG1 and XPG2) and performed isothermal titration calorimetry assays to determine their binding affinities. Structural experiments confirm the binding of both NLS peptides to Impα but, unexpectedly, they bind to the receptor as monopartite NLSs. The isothermal titration calorimetry assays demonstrated that XPG1 and XPG2 peptides bind to two separate binding sites, but with high affinity to the major NLS-binding site of the Impα, resembling classical monopartite SV40 TAg NLS. The results lead to insights about what distinguishes monopartite and bipartite NLSs, as well as the differential roles of XPG1 and XPG2 NLSs in the nuclear localization of XPG.