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5x8n

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Crystal structure of mouse importin-alpha1 bound to the nuclear localization signal of Epstein-Barr virus EBNA-LP protein

Structural highlights

5x8n is a 2 chain structure with sequence from Human herpesvirus 4 strain B95-8 and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.15Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IMA1_MOUSE Functions in nuclear protein import as an adapter protein for nuclear receptor KPNB1. Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Docking of the importin/substrate complex to the nuclear pore complex (NPC) is mediated by KPNB1 through binding to nucleoporin FxFG repeats and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to importin-beta and the three components separate and importin-alpha and -beta are re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran from importin. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus.

Publication Abstract from PubMed

Epstein-Barr virus EBNA-LP protein is a transcriptional coactivator of EBNA2. Efficient nuclear localization of EBNA-LP is essential for cooperation with EBNA2. Here, we report the crystal structure of the nuclear import adaptor importin-alpha1 bound to the nuclear localization signal (NLS) of EBNA-LP that shows EBNA-LP residues 44-RRVRRR-49 binding to the major NLS-binding site at the P0-P5 positions. In contrast to previously characterized classical NLSs that invariably have a basic residue [either lysine (in the vast majority of cases) or arginine] at the P2 position, the EBNA-LP NLS is unique in that it has valine at the P2 position. The loss of the critical P2 lysine (or arginine) is compensated by arginine at the P0 position in the EBNA-LP NLS.

Crystal structure of importin-alpha bound to the nuclear localization signal of Epstein-Barr virus EBNA-LP protein.,Nakada R, Matsuura Y Protein Sci. 2017 Apr 6. doi: 10.1002/pro.3173. PMID:28383161^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Nakada R, Matsuura Y. Crystal structure of importin-alpha bound to the nuclear localization signal of Epstein-Barr virus EBNA-LP protein. Protein Sci. 2017 Apr 6. doi: 10.1002/pro.3173. PMID:28383161 doi:http://dx.doi.org/10.1002/pro.3173