4BSM : Crystal structure of the Nuclear Export Receptor CRM1 (exportin-1) lacking the C-terminal helical extension at 4.5A

Experimental Technique/Method:X-RAY DIFFRACTION Resolution:4.5 Classification:PROTEIN TRANSPORT Release Date:2013-07-31 Deposition Date:2013-06-10 Revision Date:2013-08-28 Molecular Weight:118863.17 Macromolecule Type:Protein Residue Count:1032 Atom Site Count:6854 DOI:10.2210/pdb4bsm/pdb Abstract: Chromosome region maintenance 1/exportin1/Xpo1 (CRM1) associates with the GTPase Ran to mediate the nuclear export of proteins bearing a leucine-rich nuclear export signal (NES). CRM1 consists of helical hairpin HEAT repeats and a C-terminal helical extension (C-extension) that inhibits the binding of NES-bearing cargos. We report the crystal structure and small-angle X-ray scattering analysis of a human CRM1 mutant with enhanced NES-binding activity due to deletion of the C-extension. We show that loss of the C-extension leads to a repositioning of CRM1's C-terminal repeats and to a more extended overall conformation. Normal mode analysis predicts reduced rigidity for the deletion mutant, consistent with an observed decrease in thermal stability. Point mutations that destabilize the C-extension shift CRM1 to the more extended conformation, reduce thermal stability, and enhance NES-binding activity. These findings suggest that an important mechanism by which the C-extension regulates CRM1's cargo-binding affinity is by modulating the conformation and flexibility of its HEAT repeats

4BSN : Crystal structure of the Nuclear Export Receptor CRM1 (exportin-1) lacking the C-terminal helical extension at 4.1A

Experimental Technique/Method:X-RAY DIFFRACTION Resolution:4.1 Classification:PROTEIN TRANSPORT Release Date:2013-07-31 Deposition Date:2013-06-11 Revision Date:2013-08-28 Molecular Weight:118863.17 Macromolecule Type:Protein Residue Count:1032 Atom Site Count:5481 DOI:10.2210/pdb4bsn/pdb Abstract: Chromosome region maintenance 1/exportin1/Xpo1 (CRM1) associates with the GTPase Ran to mediate the nuclear export of proteins bearing a leucine-rich nuclear export signal (NES). CRM1 consists of helical hairpin HEAT repeats and a C-terminal helical extension (C-extension) that inhibits the binding of NES-bearing cargos. We report the crystal structure and small-angle X-ray scattering analysis of a human CRM1 mutant with enhanced NES-binding activity due to deletion of the C-extension. We show that loss of the C-extension leads to a repositioning of CRM1's C-terminal repeats and to a more extended overall conformation. Normal mode analysis predicts reduced rigidity for the deletion mutant, consistent with an observed decrease in thermal stability. Point mutations that destabilize the C-extension shift CRM1 to the more extended conformation, reduce thermal stability, and enhance NES-binding activity. These findings suggest that an important mechanism by which the C-extension regulates CRM1's cargo-binding affinity is by modulating the conformation and flexibility of its HEAT repeats