PDBsum entry: 1wa5

Nuclear transport

PDB id: 1wa5

Contents

Protein chains

170 a.a. *

464 a.a. *

938 a.a. *

Ligands

GTP

Metals

_MG

Waters ×472

* Residue conservation analysis

PDB id:

1wa5

Name:

Nuclear transport

Title:

Crystal structure of the exportin cse1p complexed with its cargo (kap60p) and rangtp

Structure:

Gtp-binding nuclear protein ran. Chain: a. Fragment: residues 1-176. Synonym: gtpase ran, ras-like protein tc4. Engineered: yes. Importin alpha re-exporter. Chain: c. Synonym: chromosome segregation protein cse1, cse1p. Engineered: yes.

Source:

Canis familiaris. Dog. Organism_taxid: 9615. Expressed in: escherichia coli. Expression_system_taxid: 469008. Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932.

Biol. unit:

Trimer (from PDB file)

Resolution:

2.00Å R-factor: 0.234 R-free: 0.267

Authors:

Y.Matsuura,M.Stewart

Key ref:

Y.Matsuura and M.Stewart (2004). Structural basis for the assembly of a nuclear export complex. Nature, 432, 872-877. PubMed id: 15602554 DOI: 10.1038/nature03144

Date:

23-Oct-04 Release date: 13-Dec-04

Protein chain

P62825  (RAN_CANFA) -  GTP-binding nuclear protein Ran

Seq: 216 a.a.

Struc: 170 a.a.

Protein chain

Q02821  (IMA1_YEAST) -  Importin subunit alpha

Seq: 542 a.a.

Struc: 464 a.a.

Protein chain

P33307  (CSE1_YEAST) -  Importin alpha re-exporter

Seq: 960 a.a.

Struc: 938 a.a.

 Gene Ontology (GO) functional annotation 

• Cellular component: cytoplasm (5 terms)
• Biological process: cell cycle (13 terms)
• Biochemical function: binding (6 terms)

DOI no: 10.1038/nature03144

Nature 432:872-877 (2004)

PubMed id: 15602554

Structural basis for the assembly of a nuclear export complex.

Y.Matsuura, M.Stewart.

ABSTRACT

The nuclear import and export of macromolecular cargoes through nuclear pore complexes is mediated primarily by carriers such as importin-beta. Importins carry cargoes into the nucleus, whereas exportins carry cargoes to the cytoplasm. Transport is orchestrated by nuclear RanGTP, which dissociates cargoes from importins, but conversely is required for cargo binding to exportins. Here we present the 2.0 A crystal structure of the nuclear export complex formed by exportin Cse1p complexed with its cargo (Kap60p) and RanGTP, thereby providing a structural framework for understanding nuclear protein export and the different functions of RanGTP in export and import. In the complex, Cse1p coils around both RanGTP and Kap60p, stabilizing the RanGTP-state and clamping the Kap60p importin-beta-binding domain, ensuring that only cargo-free Kap60p is exported. Mutagenesis indicated that conformational changes in exportins couple cargo binding to high affinity for RanGTP, generating a spring-loaded molecule to facilitate disassembly of the export complex following GTP hydrolysis in the cytoplasm.

Selected figure(s)

Figure 1.
Figure 1: Two orthogonal views, showing an overview of the structure of the Cse1p:Kap60p:RanGTP complex. The figure illustrates how Cse1p (yellow) envelopes RanGTP (blue), and the C-terminal region of Kap60p (green) and its IBB domain (magenta). The Cse1p -helices are represented by cylinders, whereas the HEAT8 insert and HEAT19 loop are highlighted in pink and orange, respectively. The ARM repeats of Kap60p and HEAT repeats of Cse1p are labelled A1 -A10 and H1 -H20, respectively. GTP is shown as spacefilling spheres. Key residues mentioned in the text are shown in ball-and-stick representation.

Figure 3.
Figure 3: Role of Ran in the export complex. a, Interfaces between Cse1p (yellow) and Ran (switch I, magenta; switch II, orange). Ran Arg 76 and Asp 77 in the switch II loop are key components of the Cse1p N-interface, whereas Lys 37 (switch I loop) and Lys 152 bind the C-interface. An omit-annealed F[o] -F[c] map around GTP at 3.5 is superimposed, confirming the nucleotide state. b, Ran Arg 95, Lys 99, Lys 130 and Lys 134 are key components of the interface between RanGTP (blue) and Kap60p (green). c, Docking RanBD1 onto the Cse1p:Kap60p:RanGTP complex shows a steric clash between Cse1p and the RanGTP C terminus. The coordinates of Ran bound to RanBD1 (red) were superimposed with Ran (residues 1 -176) in the Cse1p:Kap60p:RanGTP complex. C-terminal residues of Ran (176 -210) in the Ran-RanBD1 complex, dark blue; other colour coding as Fig. 1. d, Model for Cse1p:Kap60p:RanGTP complex assembly. Dotted lines represent interactions. In the absence of Kap60p, Cse1p has a lower-energy conformation that binds Ran at only one site. When Kap60p binds, Cse1p is distorted into a higher-energy state that allows Ran to bind to the second site, generating a spring-loaded complex that would disassemble spontaneously on RanGTP hydrolysis. The representation of Cse1p here is highly schematic, and is intended only to imply a conformational change and not the precise structure of either state.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2004, 432, 872-877) copyright 2004.

Figures were selected by the author.