A mutation in budding yeast BRR6 affecting nuclear envelope insertion of the spindle pole body

Gardner, Jennifer M.; O’Toole, Eileen; Jaspersen, Sue L.

doi:10.17912/micropub.biology.000463

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…Brr6 orthologues are expressed only in organisms undergoing a closed mitosis, such as fission yeast or budding yeast [47,48]. In both yeasts, Brr6 promotes spindle pole body insertion into the nuclear envelope [46,49]. The fact that the Dictyostelium genome contains a clear homologue of this protein family argues in favor of a conserved mechanism of centrosome insertion.…”

Section: Discussionmentioning

confidence: 99%

Temporal Changes in Nuclear Envelope Permeability during Semi-Closed Mitosis in Dictyostelium Amoebae

Mitic

Meyer

Gräf

et al. 2023

Cells

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The Amoebozoan Dictyostelium discoideum exhibits a semi-closed mitosis in which the nuclear membranes remain intact but become permeabilized to allow tubulin and spindle assembly factors to access the nuclear interior. Previous work indicated that this is accomplished at least by partial disassembly of nuclear pore complexes (NPCs). Further contributions by the insertion process of the duplicating, formerly cytosolic, centrosome into the nuclear envelope and nuclear envelope fenestrations forming around the central spindle during karyokinesis were discussed. We studied the behavior of several Dictyostelium nuclear envelope, centrosomal, and nuclear pore complex (NPC) components tagged with fluorescence markers together with a nuclear permeabilization marker (NLS-TdTomato) by live-cell imaging. We could show that permeabilization of the nuclear envelope during mitosis occurs in synchrony with centrosome insertion into the nuclear envelope and partial disassembly of nuclear pore complexes. Furthermore, centrosome duplication takes place after its insertion into the nuclear envelope and after initiation of permeabilization. Restoration of nuclear envelope integrity usually occurs long after re-assembly of NPCs and cytokinesis has taken place and is accompanied by a concentration of endosomal sorting complex required for transport (ESCRT) components at both sites of nuclear envelope fenestration (centrosome and central spindle).

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Section: Discussionmentioning

confidence: 99%

Temporal Changes in Nuclear Envelope Permeability during Semi-Closed Mitosis in Dictyostelium Amoebae

Mitic

Meyer

Gräf

et al. 2023

Cells

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A perinuclear α-helix with amphipathic features in Brl1 promotes NPC assembly

Vitale

Khan

Neuner

et al. 2022

MBoC

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How nuclear pore complexes (NPC) assemble in the intact nuclear envelope (NE) is only rudimentarily understood. Nucleoporins accumulate at the inner NE (INM), deform this membrane towards the outer nuclear membrane (ONM) and eventually INM and ONM fuse by an unclear mechanism. In budding yeast, the integral membrane protein Brl1 that transiently associates with NPC assembly intermediates is involved in INM/ONM fusion during NPC assembly but leaving the molecular mechanism open. AlphaFold predictions indicate that Brl1-like proteins carry as common motifs an α-helix with amphipathic features (AαH) and a disulfide-stabilized anti-parallel helix bundle (DAH) in the perinuclear space. Mutants with defective AαH ( brl1F391E, brl1F391P, brl1L402E) impair the essential function of BRL1. Overexpression of brl1F391E promotes formation of INM and ONM enclosed petal-like structures that carry nucleoporins at their base suggesting that they are derived from an NPC assembly attempt with failed INM/ONM fusion. Accordingly, brl1F391E expression triggers mis-localisation of Nup159 and Nup42 and to a lesser extent Nsp1 that localize on the cytoplasmic face of the NPC. The DAH also contributes to the function of Brl1 and AαH has functions independent of DAH. We propose that AαH and DAH in Brl1 promote INM/ONM fusion during NPC assembly.

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A mutation in budding yeast BRR6 affecting nuclear envelope insertion of the spindle pole body

Cited by 2 publications

References 22 publications

Temporal Changes in Nuclear Envelope Permeability during Semi-Closed Mitosis in Dictyostelium Amoebae

Temporal Changes in Nuclear Envelope Permeability during Semi-Closed Mitosis in Dictyostelium Amoebae

A perinuclear α-helix with amphipathic features in Brl1 promotes NPC assembly

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