Structural and mutational analysis reveals that CTNNBL1 binds NLSs in a manner distinct from that of its closest armadillo-relative, karyopherin α

FEBS Lett. 2014 Jan 3;588(1):21-7. doi: 10.1016/j.febslet.2013.11.013. Epub 2013 Nov 20.

Abstract

CTNNBL1 is a spliceosome-associated protein that binds nuclear localization signals (NLSs) in splice factors CDC5L and Prp31 as well as the antibody diversifying enzyme AID. Here, crystal structures of human CTNNBL1 reveal a distinct structure from its closest homologue karyopherin-α. CTNNBL1 comprises a HEAT-like domain (including a nuclear export signal), a central armadillo domain, and a coiled-coil C-terminal domain. Structure-guided mutations of the region homologous to the karyopherin-α NLS-binding site fail to disrupt CTNNBL1-NLS interactions. Our results identify CTNNBL1 as a unique selective NLS-binding protein with striking differences from karyopherin-αs.

Keywords: Armadillo domain; Nuclear import; Splicing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Apoptosis Regulatory Proteins / chemistry*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Armadillo Domain Proteins / chemistry
  • Armadillo Domain Proteins / genetics
  • Armadillo Domain Proteins / metabolism
  • Binding Sites / genetics
  • Crystallography, X-Ray
  • DNA Mutational Analysis
  • Electrophoresis, Polyacrylamide Gel
  • HEK293 Cells
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Nuclear Localization Signals / chemistry*
  • Nuclear Localization Signals / metabolism
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid
  • alpha Karyopherins / chemistry*
  • alpha Karyopherins / genetics
  • alpha Karyopherins / metabolism

Substances

  • Apoptosis Regulatory Proteins
  • Armadillo Domain Proteins
  • CTNNBL1 protein, human
  • Nuclear Localization Signals
  • Nuclear Proteins
  • alpha Karyopherins