scholarly journals Deletion of nudC, a nuclear migration gene of Aspergillus nidulans, causes morphological and cell wall abnormalities and is lethal.

1997 ◽  
Vol 8 (9) ◽  
pp. 1735-1749 ◽  
Author(s):  
Y H Chiu ◽  
X Xiang ◽  
A L Dawe ◽  
N R Morris
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Protein Function ◽  
Spindle Pole Body ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein ◽  
Spindle Pole ◽  
Polymer Composition ◽  
Gene Products ◽  
Fungal Cell

Nuclear migration is required for normal development in both higher and lower eukaryotes. In fungi this process is mediated by cytoplasmic dynein. It is believed that this motor protein is anchored to the cell membrane and moves nuclei by capturing and pulling on spindle pole body microtubules. To date, four genes have been identified and shown to be required for this process in Aspergillus nidulans. The nudA and nudG genes, respectively, encode the heavy and light chains of cytoplasmic dynein, and the nudF and nudC gene products encode proteins of 49 and 22 kDa. The precise biochemical functions of the nudF and nudC genes have not yet been identified. In this report we further investigate NUDC protein function by deleting the nudC gene. Surprisingly, although deletion of nudA and nudF affect nuclear migration, deletion of nudC profoundly affected the morphology and composition of the cell wall. Spores of the strain deleted for nudC grew spherically and lysed. The thickness of the cell wall was increased in the deletion mutant and wall polymer composition was abnormal. This phenotype could be repressed by growth on osmotically buffered medium at low temperature. Similar, but less severe, effects were also noted in a strain depleted for NUDC by down-regulation. These results suggest a possible relationship between fungal cell wall biosynthesis and nuclear migration.

scholarly journals The spindle pole-body localization of activated cytoplasmic dynein is cell cycle-dependent in Aspergillus nidulans

2021 ◽  
Vol 148 ◽  
pp. 103519
Author(s):  
Baronger Dowell Bieger ◽  
Aysha H. Osmani ◽  
Xin Xiang ◽  
Martin J. Egan
Keyword(s):  
Cell Cycle ◽  
Aspergillus Nidulans ◽  
Spindle Pole Body ◽  
Cytoplasmic Dynein ◽  
Spindle Pole ◽  
Pole Body ◽  
Cycle Dependent

scholarly journals Role of fungal dynein in hyphal growth, microtubule organization, spindle pole body motility and nuclear migration

1998 ◽  
Vol 111 (11) ◽  
pp. 1555-1566 ◽  
Author(s):  
S. Inoue ◽  
B.G. Turgeon ◽  
O.C. Yoder ◽  
J.R. Aist
Keyword(s):  
Spindle Pole Body ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein ◽  
Spindle Pole ◽  
Wild Type ◽  
Interphase Nuclei ◽  
Spindle Pole Bodies ◽  
Body Motility ◽  
Tip Cells ◽  
Hyphal Tip

Cytoplasmic dynein is a microtubule-associated motor protein with several putative subcellular functions. Sequencing of the gene (DHC1) for cytoplasmic dynein heavy chain of the filamentous ascomycete, Nectria haematococca, revealed a 4,349-codon open reading frame (interrupted by two introns) with four highly conserved P-loop motifs, typical of cytoplasmic dynein heavy chains. The predicted amino acid sequence is 78.0% identical to the cytoplasmic dynein heavy chain of Neurospora crassa, 70.2% identical to that of Aspergillus nidulans and 24.8% identical to that of Saccharomyces cerevisiae. The genomic copy of DHC1 in N. haematococca wild-type strain T213 was disrupted by inserting a selectable marker into the central motor domain. Mutants grew at 33% of the wild-type rate, forming dense compact colonies composed of spiral and highly branched hyphae. Major cytological phenotypes included (1) absence of aster-like arrays of cytoplasmic microtubules focused at the spindle pole bodies of post-mitotic and interphase nuclei, (2) limited post-mitotic nuclear migration, (3) lack of spindle pole body motility at interphase, (4) failure of spindle pole bodies to anchor interphase nuclei, (5) nonuniform distribution of interphase nuclei and (6) small or ephemeral Spitzenkorper at the apices of hyphal tip cells. Microtubule distribution in the apical region of tip cells of the mutant was essentially normal. The nonuniform distribution of nuclei in hyphae resulted primarily from a lack of both post-mitotic nuclear migration and anchoring of interphase nuclei by the spindle pole bodies. The results support the hypothesis that DHC1 is required for the motility and functions of spindle pole bodies, normal secretory vesicle transport to the hyphal apex and normal hyphal tip cell morphogenesis.

scholarly journals Cytoplasmic dynein is involved in nuclear migration in Aspergillus nidulans.

1994 ◽  
Vol 91 (6) ◽  
pp. 2100-2104 ◽  
Author(s):  
X. Xiang ◽  
S. M. Beckwith ◽  
N. R. Morris
Keyword(s):  
Aspergillus Nidulans ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein

A Screen for Dynein Synthetic Lethals in Aspergillus nidulans Identifies Spindle Assembly Checkpoint Genes and Other Genes Involved in Mitosis

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 101-116
Author(s):  
Vladimir P Efimov ◽  
N Ronald Morris
Keyword(s):  
Aspergillus Nidulans ◽  
Spindle Assembly Checkpoint ◽  
Genetic Interaction ◽  
Synthetic Lethality ◽  
Spindle Assembly ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein ◽  
Vesicle Transport ◽  
Synthetic Lethal ◽  
Checkpoint Genes

Abstract Cytoplasmic dynein is a ubiquitously expressed microtubule motor involved in vesicle transport, mitosis, nuclear migration, and spindle orientation. In the filamentous fungus Aspergillus nidulans, inactivation of cytoplasmic dynein, although not lethal, severely impairs nuclear migration. The role of dynein in mitosis and vesicle transport in this organism is unclear. To investigate the complete range of dynein function in A. nidulans, we searched for synthetic lethal mutations that significantly reduced growth in the absence of dynein but had little effect on their own. We isolated 19 sld (synthetic lethality without dynein) mutations in nine different genes. Mutations in two genes exacerbate the nuclear migration defect seen in the absence of dynein. Mutations in six other genes, including sldA and sldB, show a strong synthetic lethal interaction with a mutation in the mitotic kinesin bimC and, thus, are likely to play a role in mitosis. Mutations in sldA and sldB also confer hypersensitivity to the microtubule-destabilizing drug benomyl. sldA and sldB were cloned by complementation of their mutant phenotypes using an A. nidulans autonomously replicating vector. Sequencing revealed homology to the spindle assembly checkpoint genes BUB1 and BUB3 from Saccharomyces cerevisiae. Genetic interaction between dynein and spindle assembly checkpoint genes, as well as other mitotic genes, indicates that A. nidulans dynein plays a role in mitosis. We suggest a model for dynein motor action in A. nidulans that can explain dynein involvement in both mitosis and nuclear distribution.

scholarly journals Conserved Processes and Lineage-Specific Proteins in Fungal Cell Wall Evolution

2007 ◽  
Vol 6 (12) ◽  
pp. 2269-2277 ◽  
Author(s):  
Juan E. Coronado ◽  
Saad Mneimneh ◽  
Susan L. Epstein ◽  
Wei-Gang Qiu ◽  
Peter N. Lipke
Keyword(s):  
Cell Wall ◽  
Protein Function ◽  
Phosphatidyl Inositol ◽  
Low Complexity ◽  
Open Reading Frames ◽  
Specific Cell ◽  
Glycosyl Hydrolases ◽  
Fungal Cell ◽  
Structural Wall ◽  
Lineage Specificity

ABSTRACT The cell wall is a defining organelle that differentiates fungi from its sister clades in the opisthokont superkingdom. With a sensitive technique to align low-complexity protein sequences, we have identified 187 cell wall-related proteins in Saccharomyces cerevisiae and determined the presence or absence of homologs in 17 other fungal genomes. There were both conserved and lineage-specific cell wall proteins, and the degree of conservation was strongly correlated with protein function. Some functional classes were poorly conserved and lineage specific: adhesins, structural wall glycoprotein components, and unannotated open reading frames. These proteins are primarily those that are constituents of the walls themselves. On the other hand, glycosyl hydrolases and transferases, proteases, lipases, proteins in the glycosyl phosphatidyl-inositol-protein synthesis pathway, and chaperones were strongly conserved. Many of these proteins are also conserved in other eukaryotes and are associated with wall synthesis in plants. This gene conservation, along with known similarities in wall architecture, implies that the basic architecture of fungal walls is ancestral to the divergence of the ascomycetes and basidiomycetes. The contrasting lineage specificity of wall resident proteins implies diversification. Therefore, fungal cell walls consist of rapidly diversifying proteins that are assembled by the products of an ancestral and conserved set of genes.

scholarly journals Reorientation of Mispositioned Spindles in Short Astral Microtubule Mutantspc72Δ Is Dependent on Spindle Pole Body Outer Plaque and Kar3 Motor Protein

2002 ◽  
Vol 13 (4) ◽  
pp. 1366-1380 ◽  
Author(s):  
Dominic Hoepfner ◽  
Florian Schaerer ◽  
Arndt Brachat ◽  
Achim Wach ◽  
Peter Philippsen
Keyword(s):  
Spindle Pole Body ◽  
Time Lapse ◽  
Nuclear Migration ◽  
Spindle Pole ◽  
Astral Microtubule ◽  
Spindle Pole Bodies ◽  
Microtubule Motor ◽  
Microtubule Formation ◽  
Mother Cells

Nuclear migration and positioning in Saccharomyces cerevisiae depend on long astral microtubules emanating from the spindle pole bodies (SPBs). Herein, we show by in vivo fluorescence microscopy that cells lacking Spc72, the SPB receptor of the cytoplasmic γ-tubulin complex, can only generate very short (<1 μm) and unstable astral microtubules. Consequently, nuclear migration to the bud neck and orientation of the anaphase spindle along the mother-bud axis are absent in these cells. However,SPC72 deletion is not lethal because elongated but misaligned spindles can frequently reorient in mother cells, permitting delayed but otherwise correct nuclear segregation. High-resolution time-lapse sequences revealed that this spindle reorientation was most likely accomplished by cortex interactions of the very short astral microtubules. In addition, a set of double mutants suggested that reorientation was dependent on the SPB outer plaque and the astral microtubule motor function of Kar3 but not Kip2/Kip3/Dhc1, or the cortex components Kar9/Num1. Our observations suggest that Spc72 is required for astral microtubule formation at the SPB half-bridge and for stabilization of astral microtubules at the SPB outer plaque. In addition, our data exclude involvement of Spc72 in spindle formation and elongation functions.

scholarly journals Cytoplasmic Dynein's Mitotic Spindle Pole Localization Requires a Functional Anaphase-promoting Complex, γ-Tubulin, and NUDF/LIS1 in Aspergillus nidulans

2005 ◽  
Vol 16 (8) ◽  
pp. 3591-3605 ◽  
Author(s):  
Shihe Li ◽  
C. Elizabeth Oakley ◽  
Guifang Chen ◽  
Xiaoyan Han ◽  
Berl R. Oakley ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Cytoplasmic Dynein ◽  
Spindle Pole ◽  
Chromosome Loss ◽  
Anaphase Promoting Complex ◽  
Mitotic Progression ◽  
Spindle Poles ◽  
Dynein Motor ◽  
Chromosome Separation ◽  
Spindle Elongation

In Aspergillus nidulans, cytoplasmic dynein and NUDF/LIS1 are found at the spindle poles during mitosis, but they seem to be targeted to this location via different mechanisms. The spindle pole localization of cytoplasmic dynein requires the function of the anaphase-promoting complex (APC), whereas that of NUDF does not. Moreover, although NUDF's localization to the spindle poles does not require a fully functional dynein motor, the function of NUDF is important for cytoplasmic dynein's targeting to the spindle poles. Interestingly, a γ-tubulin mutation, mipAR63, nearly eliminates the localization of cytoplasmic dynein to the spindle poles, but it has no apparent effect on NUDF's spindle pole localization. Live cell analysis of the mipAR63 mutant revealed a defect in chromosome separation accompanied by unscheduled spindle elongation before the completion of anaphase A, suggesting that γ-tubulin may recruit regulatory proteins to the spindle poles for mitotic progression. In A. nidulans, dynein is not apparently required for mitotic progression. In the presence of a low amount of benomyl, a microtubule-depolymerizing agent, however, a dynein mutant diploid strain exhibits a more pronounced chromosome loss phenotype than the control, indicating that cytoplasmic dynein plays a role in chromosome segregation.

scholarly journals Extragenic suppressors of a dynein mutation that blocks nuclear migration in Aspergillus nidulans.

Genetics ◽  
1995 ◽  
Vol 139 (3) ◽  
pp. 1223-1232 ◽  
Author(s):  
G H Goldman ◽  
N R Morris
Keyword(s):  
Aspergillus Nidulans ◽  
Heavy Chain ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein ◽  
Complementation Group ◽  
Large Molecular Weight ◽  
Weight Protein ◽  
Partial Suppression ◽  
Extragenic Suppressors

Abstract Cytoplasmic dynein is a large molecular weight protein complex that functions as a microtubule-dependent, negative, end-directed "motor." Mutations in nudA, which encodes the heavy chain of cytoplasmic dynein, inhibit nuclear migration in Aspergillus nidulans. This paper describes the selection and characterization of extragenic suppressors of the nudA1 mutation preparatory to the identification of other proteins that interact directly or indirectly with the cytoplasmic dynein heavy chain. To facilitate future cloning of the suppressor genes, we have searched particularly for extragenic suppressor mutations that also convey a selectable phenotype, such as cold or dimethyl sulfoxide sensitivity. Genetic analysis of 16 revertants has defined at least five extragenic suppressors of nudA1 (snaA-E). All the sna mutations except one were recessive in diploids homozygous for nudA1 and heterozygous for sna mutations. To characterize the nuclear migration phenotype in the sna mutants, conidia of one representative of each complementation group were germinated, fixed and nuclei stained. The sna mutants display partial suppression of the nudA1 nuclear migration defect. Although conidiophores were produced in the sna mutants, they failed to develop normally and to produce spores. Examination of the nudA1,sna conidiophores under the microscope showed that nuclear migration into the metulae and phialides was defective.

scholarly journals The spindle pole body of Aspergillus nidulans is asymmetrical and contains changing numbers of γ-tubulin complexes

2019 ◽  
Vol 132 (24) ◽  
pp. jcs234799 ◽  
Author(s):  
Xiaolei Gao ◽  
Marjorie Schmid ◽  
Ying Zhang ◽  
Sayumi Fukuda ◽  
Norio Takeshita ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Pole Body
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