Structures of Importins and Exportins

Baumhardt, J.M.; Chook, Yuh Min

doi:10.1007/978-3-319-77309-4_6

Cited by 4 publications

(2 citation statements)

References 168 publications

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“…Unlike other import cargos that are easily dissociated from their importins by RanGTP, the GTPase cannot release H2A-H2B from Kap114 or Imp9 (Mosammaparast, del Rosario, and Pemberton 2005; J. Baumhardt and Chook 2018; Padavannil et al 2019). Instead, RanGTP binds to form a stable RanGTP•Kap114/Imp9•H2A-H2B complex.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of RanGTP priming H2A-H2B release from Kap114 in an atypical RanGTP•Kap114•H2A-H2B complex

Jiou

Shaffer²,

Bernardes

et al. 2022

Preprint

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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 (Padavannil et al. 2019). 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 RanGTP•Importin-9•H2A-H2B facilitates H2A-H2B release to the assembling nucleosome (Padavannil et al. 2019). 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. In combination with hydrogen-deuterium exchange analysis of Importin-9 complexes and nucleosome assembly assays, we explain how the conserved Kap114/Importin-9 importins bind H2A-H2B and RanGTP simultaneously and how the GTPase primes histone transfer to the nucleosome. We show that RanGTP binds to the N-terminal repeats of Kap114/Importin-9 as in Kap114/Importin-9•RanGTP, and H2A-H2B binds via its acidic patch to the Kap114/Importin-9 C-terminal repeats as in Kap114/Importin-9•H2A-H2B. RanGTP-binding in RanGTP•Kap114•H2A-H2B changes Kap114/Importin-9 conformation such that it no longer contacts the surface of H2A-H2B proximal to the H2A docking domain that drives nucleosome assembly, positioning it for transfer to the assembling nucleosome. The reduced affinity of RanGTP for Kap114/Importin-9 when H2A-H2B is bound may ensure release of H2A-H2B only at chromatin.

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Section: Discussionmentioning

confidence: 99%

Mechanism of RanGTP priming H2A-H2B release from Kap114 in an atypical RanGTP•Kap114•H2A-H2B complex

Jiou

Shaffer²,

Bernardes

et al. 2022

Preprint

Self Cite

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“…They translocate in a facilitated manner through the barrier, draw energy from the RanGTPase system, and pump cargoes through NPCs. According to the direction of cargo transport, NTRs can be grouped into importins and exportins (reviewed by Güttler and Görlich, 2011; Christie et al, 2016; Baumhardt and Chook, 2018).…”

Section: Introductionmentioning

confidence: 99%

Engineered SUMO/protease system identifies Pdr6 as a bidirectional nuclear transport receptor

Rodriguez

Frey

Görlich

2019

Journal of Cell Biology

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Cleavage of affinity tags by specific proteases can be exploited for highly selective affinity chromatography. The SUMO/SENP1 system is the most efficient for such application but fails in eukaryotic expression because it cross-reacts with endogenous proteases. Using a novel selection system, we have evolved the SUMOEu/SENP1Eu pair to orthogonality with the yeast and animal enzymes. SUMOEu fusions therefore remain stable in eukaryotic cells. Likewise, overexpressing a SENP1Eu protease is nontoxic in yeast. We have used the SUMOEu system in an affinity-capture-proteolytic-release approach to identify interactors of the yeast importin Pdr6/Kap122. This revealed not only further nuclear import substrates such as Ubc9, but also Pil1, Lsp1, eIF5A, and eEF2 as RanGTP-dependent binders and thus as export cargoes. We confirmed that Pdr6 functions as an exportin in vivo and depletes eIF5A and eEF2 from cell nuclei. Thus, Pdr6 is a bidirectional nuclear transport receptor (i.e., a biportin) that shuttles distinct sets of cargoes in opposite directions.

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Structure-based in-silico identification of natural compounds as potential inhibitors of ran GTPase for breast cancer treatment

Nagar,

Prajapati,

Priya

et al. 2024

Biocatalysis and Agricultural Biotechnology

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Structures of Importins and Exportins

Cited by 4 publications

References 168 publications

Mechanism of RanGTP priming H2A-H2B release from Kap114 in an atypical RanGTP•Kap114•H2A-H2B complex

Mechanism of RanGTP priming H2A-H2B release from Kap114 in an atypical RanGTP•Kap114•H2A-H2B complex

Engineered SUMO/protease system identifies Pdr6 as a bidirectional nuclear transport receptor

Structure-based in-silico identification of natural compounds as potential inhibitors of ran GTPase for breast cancer treatment

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