8f19

Cryo-EM structure of Kap114 bound to Gsp1 (RanGTP)

spinqualitylabelsall models 8f19, resolution 3.49Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8f19 is a 2 chain structure with sequence from Saccharomyces cerevisiae S288C. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.49Å Ligands: GTP, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function IMB5_YEAST Required for nuclear protein import and mediates docking of import substrate to distinct nucleoporins. Serves a receptor for nuclear localization signals. Mediates the nuclear import of TATA-binding protein (TBP) and of histones H2A and H2B. Publication Abstract from PubMed Previously, we showed that the nuclear import receptor Importin-9 wraps around the H2A-H2B core to chaperone and transport it from the cytoplasm to the nucleus. However, unlike most nuclear import systems where RanGTP dissociates cargoes from their importins, RanGTP binds stably to the Importin-9*H2A-H2B complex, and formation of the ternary RanGTP*Importin-9*H2A-H2B complex facilitates H2A-H2B release to the assembling nucleosome. It was unclear how RanGTP and the cargo H2A-H2B can bind simultaneously to an importin, and how interactions of the three components position H2A-H2B for release. Here, we show cryo-EM structures of Importin-9*RanGTP and of its yeast homolog Kap114, including Kap114*RanGTP, Kap114*H2A-H2B, and RanGTP*Kap114*H2A-H2B, to explain how the conserved Kap114 binds H2A-H2B and RanGTP simultaneously and how the GTPase primes histone transfer to the nucleosome. In the ternary complex, RanGTP binds to the N-terminal repeats of Kap114 in the same manner as in the Kap114/Importin-9*RanGTP complex, and H2A-H2B binds via its acidic patch to the Kap114 C-terminal repeats much like in the Kap114/Importin-9*H2A-H2B complex. Ran binds to a different conformation of Kap114 in the ternary RanGTP*Kap114*H2A-H2B complex. Here, Kap114 no longer contacts the H2A-H2B surface proximal to the H2A docking domain that drives nucleosome assembly, positioning it for transfer to the assembling nucleosome or to dedicated H2A-H2B chaperones in the nucleus. Mechanism of RanGTP priming H2A-H2B release from Kap114 in an atypical RanGTP*Kap114*H2A-H2B complex.,Jiou J, Shaffer JM, Bernades NE, Fung HYJ, Kikumoto Dias J, D'Arcy S, Chook YM Proc Natl Acad Sci U S A. 2023 Jul 18;120(29):e2301199120. doi: , 10.1073/pnas.2301199120. Epub 2023 Jul 14. PMID:37450495 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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