THE BUDDING YEAST SPINDLE POLE BODY: Structure, Duplication, and Function

Jaspersen, Sue L.; Winey, Mark

doi:10.1146/annurev.cellbio.20.022003.114106

Cited by 260 publications

(325 citation statements)

References 129 publications

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“…The spindle pole body (SPB) 1 is the microtubule organizing center of Saccharomyces cereVisiae (1,2). This large multiprotein complex functions to coordinate and nucleate both nuclear and cytoplasmic microtubules and is necessary for chromosome segregation, nuclear positioning, and karyogamy.…”

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confidence: 99%

Analysis of Coiled-Coil Interactions between Core Proteins of the Spindle Pole Body

et al. 2008

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The spindle pole body (SPB) is a multiprotein complex that organizes microtubules in yeast. Due to its large size and association with the nuclear membrane, little is known about its detailed structure. In particular, although many SPB components and some of the interactions between them have been identified, the molecular details of how most of these interactions occur are not known. The prevalence of predicted coiled-coil regions in SPB proteins suggests that some interactions may occur via coiled coils. Here this hypothesis is supported by biochemical characterization of isolated coiled-coil peptides derived from SPB proteins. Formation of four strongly self-associating coiled-coil complexes from Spc29, Spc42, and Spc72 was demonstrated by circular dichroism (CD) spectroscopy and a fluorescence resonance energy transfer (FRET) assay. Many weaker self-and heteroassociations were also detected by CD, FRET, and/or cross-linking. The thermal stabilities of nine candidate homooligomers were assessed; six unfolded cooperatively with melting temperatures ranging from <11 to >50 °C. Solution studies established that coiled-coil peptides derived from Spc42 and Spc72 form parallel dimers, and this was confirmed for Spc42 by a high-resolution crystal structure. These data contribute to a growing body of knowledge that will ultimately provide a detailed model of the SPB structure.

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confidence: 99%

Analysis of Coiled-Coil Interactions between Core Proteins of the Spindle Pole Body

et al. 2008

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“…Sgm1, Sla2, Spc72, Ltv1, and Hpa3 represent novel interaction partners for Xpo1. These proteins are involved in a variety of cellular pro- cesses such as membrane cytoskeleton assembly (Sla2 [32]), mitotic spindle assembly (Spc72 [35]), and chromatin modification (Hpa3 [77]). For Ltv1, a role in the Xpo1-mediated export of small ribosomal subunits has recently been shown (59).…”

Section: Resultsmentioning

confidence: 99%

“…Spc72 was particularly interesting since it is a cytoplasmic protein that functions as a structural component of the yeast SPB. This supramolecular protein complex is embedded in the nuclear membrane and is required to nucleate cytoplasmic and nuclear MTs for mitotic spindle assembly (35). During cytoplasmic MT nucleation, Spc72 interacts with the ␥-tubulin complex consisting of Spc97, Spc98, and Tub4 (39).…”

Section: Resultsmentioning

confidence: 99%

“…Under the electron microscope, it is a multilayered high-molecular-weight structure embedded in the nuclear envelope (9). Cytoplasmic and nuclear surfaces of the SPB are known as outer and inner plaques and anchor both cytoplasmic and nuclear spindle fibers, which are spatially and functionally distinct (35). Nucleation of MTs at the SPB is mediated by the ␥-tubulin (Tub4) complex that binds to the inner and outer plaques of the SPB via two specific Tub4 complex receptors, Spc110 and Spc72, respectively (56).…”

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confidence: 99%

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Nuclear Export Receptor Xpo1/Crm1 Is Physically and Functionally Linked to the Spindle Pole Body in Budding Yeast

Neuber

Franke

Wittstruck

et al. 2008

Molecular and Cellular Biology

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The spindle pole body (SPB) represents the microtubule organizing center in the budding yeast Saccharomyces cerevisiae. It is a highly structured organelle embedded in the nuclear membrane, which is required to anchor microtubules on both sides of the nuclear envelope. The protein Spc72, a component of the SPB, is located at the cytoplasmic face of this organelle and serves as a receptor for the ␥-tubulin complex. In this paper we show that it is also a binding partner of the nuclear export receptor Xpo1/Crm1. Xpo1 binds its cargoes in a Ran-dependent fashion via a short leucine-rich nuclear export signal (NES). We show that binding of Spc72 to Xpo1 depends on Ran-GTP and a functional NES in Spc72. Mutations in this NES have severe consequences for mitotic spindle morphology in vivo. This is also the case for xpo1 mutants, which show a reduction in cytoplasmic microtubules. In addition, we find a subpopulation of Xpo1 localized at the SPB. Based on these data, we propose a functional link between Xpo1 and the SPB and discuss a role for this exportin in spindle biogenesis in budding yeast.In eukaryotes, the movement of proteins and RNAs between the nucleus and the cytoplasm is an essential cellular process that is mediated by soluble transport receptors (26,52). In addition, the small GTPase Ran (Gsp1 in yeast) and its cytoplasmic and nuclear effectors are needed (12). Transport receptors involved in nuclear import reactions are usually termed importins, and they recognize their cargoes via a specific amino acid motif, the nuclear localization sequence, or NLS. By analogy, nuclear export reactions are mediated by so-called exportins. Xpo1 (also known as Crm1) was one of the first nuclear export receptors to be identified (23,27,50,64) and recognizes a short leucine-rich amino acid sequence on its cargo, called a nuclear export signal, or NES. Numerous export cargoes have now been identified for the mammalian Crm1 protein, including protein kinase A inhibitor PKI, p53, and the human immunodeficiency virus protein Rev (20,25,66). In addition, Crm1 is involved in the nuclear export of several classes of RNAs such as viral pre-mRNAs, ribosomal RNAs, and snRNAs (54). In contrast, few NES-containing proteins have been identified in Saccharomyces cerevisiae. Although the budding yeast Crm1 orthologue Xpo1 is involved in nuclear export of Hog1 (19), Yap1 (76), Ssb1 (62), Ace2 (36), and Prp40 (46), few of the NESs involved have been characterized at a molecular level.Recently, alongside its well-established role in nuclear export, mammalian Crm1 was shown to be involved in the control of centrosome duplication (71). Centrosomes function as microtubule (MT) organizing centers in mammalian somatic cells and direct the formation of a bipolar spindle during mitosis (reviewed in reference 6). In another study, Crm1 was found to bind to kinetochores, complex protein assemblies that are needed to establish the attachment of MTs to chromatin (4). These studies point to an unanticipated role of the exportin Crm1 in control of spin...

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“…In contrast, in many lower eukaryotes, such as the fission yeast Schizosaccharomyces pombe, the NE remains intact during mitosis despite undergoing remarkable morphological transformations, usually from a sphere to a spherical cylinder, and then to a dumbbell before eventually separating into two identical daughter nuclei (a process often referred to as ''closed mitosis'') (3,4). It is widely known that such shape evolution is driven by the poleward force generated by kinesins along with other microtubule-associated proteins that reside at the overlapping region of antiparallel spindle microtubules (MTs) nucleated from the two spindle pole bodies (SPBs) at both ends of a dividing nucleus (5)(6)(7)(8). Throughout interphase, there is only one SPB in the cytoplasm that starts to duplicate in G1/S phase, resulting in two SPBs embedded in the NE during mitosis (9).…”

Section: Introductionmentioning

confidence: 99%

Shape Transformation of the Nuclear Envelope during Closed Mitosis

Zhu

Zheng

Liu

et al. 2016

Biophysical Journal

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The nuclear envelope (NE) in lower eukaryotes such as Schizosaccharomyces pombe undergoes large morphology changes during closed mitosis. However, which physical parameters are important in governing the shape evolution of the NE, and how defects in the dividing chromosomes/microtubules are reflected in those parameters, are fundamental questions that remain unresolved. In this study, we show that improper separation of chromosomes in genetically deficient cells leads to membrane tethering or asymmetric division in contrast to the formation of two equal-sized daughter nuclei in wild-type cells. We hypothesize that the poleward force is transmitted to the nuclear membrane through its physical contact with the separated sister chromatids at the two spindle poles. A theoretical model is developed to predict the morphology evolution of the NE where key factors such as the work done by the poleward force and bending and surface energies stored in the membrane have been taken into account. Interestingly, the predicted phase diagram, summarizing the dependence of nuclear shape on the size of the load transmission regions, and the pole-to-pole distance versus surface area relationship all quantitatively agree well with our experimental observations, suggesting that this model captures the essential physics involved in closed mitosis.

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THE BUDDING YEAST SPINDLE POLE BODY: Structure, Duplication, and Function

Cited by 260 publications

References 129 publications

Analysis of Coiled-Coil Interactions between Core Proteins of the Spindle Pole Body

Analysis of Coiled-Coil Interactions between Core Proteins of the Spindle Pole Body

Nuclear Export Receptor Xpo1/Crm1 Is Physically and Functionally Linked to the Spindle Pole Body in Budding Yeast

Shape Transformation of the Nuclear Envelope during Closed Mitosis

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