scholarly journals An Extragenic Suppressor of the Mitosis-Defective bimD6 Mutation of Aspergillus nidulans Codes for a Chromosome Scaffold Protein

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 777-787 ◽  
Author(s):  
Cydne L Holt ◽  
Gregory S May
Keyword(s):  
Aspergillus Nidulans ◽  
Chromosome Segregation ◽  
Chromosome Structure ◽  
Heat Sensitivity ◽  
Restrictive Temperature ◽  
Mitotic Spindles ◽  
Normal Number ◽  
Cold Sensitive ◽  
Extragenic Suppressors ◽  
Chromosome Scaffold

Abstract We previously identified a gene, bimD, that functions in chromosome segregation and contains sequences suggesting that it may be a DNA-binding protein. Two conditionally lethal mutations in bimD arrest with aberrant mitotic spindles at restrictive temperature. These spindles have one-third the normal number of microtubules, and the chromosomes never attach to the remaining microtubules. For this reason, we hypothesized that BIMD functioned in chromosome segregation, possibly as a component of the kinetochore. To identify other components that function with bimD, we conducted a screen for extragenic suppressors of the bimD5 and bimD6 mutations. We have isolated seven cold-sensitive extragenic suppressors of bimD6 heat sensitivity that represent three or possibly four separate sud genes. We have cloned one of the suppressor genes by complementation of the cold-sensitive phenotype of the sudA3 mutation. SUDA belongs to the DA-box protein family. DA-box proteins have been shown to function in chromosome structure and segregation. Thus bimD and the sud genes cooperatively function in chromosome segregation in Aspergillus nidulans.

scholarly journals The SONBNUP98 Nucleoporin Interacts With the NIMA Kinase in Aspergillus nidulans

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1071-1081
Author(s):  
Colin P C De Souza ◽  
Kevin P Horn ◽  
Kathryn Masker ◽  
Stephen A Osmani
Keyword(s):  
Aspergillus Nidulans ◽  
Nuclear Accumulation ◽  
Cold Sensitivity ◽  
Nuclear Pore ◽  
Temperature Sensitive ◽  
Physical Interaction ◽  
Restrictive Temperature ◽  
Histone H2a ◽  
Cold Sensitive ◽  
Extragenic Suppressors

Abstract The Aspergillus nidulans NIMA kinase is essential for mitotic entry. At restrictive temperature, temperature-sensitive nimA alleles arrest in G2, before accumulation of NIMA in the nucleus. We performed a screen for extragenic suppressors of the nimA1 allele and isolated two cold-sensitive son (suppressor of nimA1) mutants. The sonA1 mutant encoded a nucleoporin that is a homolog of yeast Gle2/Rae1. We have now cloned SONB, a second nucleoporin genetically interacting with NIMA. sonB is essential and encodes a homolog of the human NUP98/NUP96 precursor. Similar to NUP98/NUP96, SONBNUP98/NUP96 is autoproteolytically cleaved to generate SONBNUP98 and SONBNUP96. SONBNUP98 localizes to the nuclear pore complex and contains a GLEBS domain (Gle2 binding sequence) that binds SONAGLE2. A point mutation within the GLEBS domain of SONB1NUP98 suppresses the temperature sensitivity of the nimA1 allele and compromises the physical interaction between SONAGLE2 and SONB1NUP98. The sonB1 mutation also causes sensitivity to hydroxyurea. We isolated the histone H2A-H2B gene pair as a copy-number suppressor of sonB1 cold sensitivity and hydroxyurea sensitivity. The data suggest that the nucleoporins SONAGLE2 and SONBNUP98 and the NIMA kinase interact and regulate nuclear accumulation of mitotic regulators to help promote mitosis.

CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae

1993 ◽  
Vol 13 (8) ◽  
pp. 4691-4702 ◽  
Author(s):  
Z Xiao ◽  
J T McGrew ◽  
A J Schroeder ◽  
M Fitzgerald-Hayes
Keyword(s):  
Chromosome Segregation ◽  
Leucine Zipper ◽  
Mitotic Chromosome ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
New Genes ◽  
Marked Chromosome ◽  
Cold Sensitive ◽  
Basic Region ◽  
Segregation Of Chromosomes

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.

scholarly journals Isolation of mip (microtubule-interacting protein) mutations of Aspergillus nidulans.

1986 ◽  
Vol 6 (8) ◽  
pp. 2963-2968 ◽  
Author(s):  
C F Weil ◽  
C E Oakley ◽  
B R Oakley
Keyword(s):  
Aspergillus Nidulans ◽  
Chromosomal Rearrangements ◽  
Cold Sensitivity ◽  
Heat Sensitivity ◽  
Wild Type ◽  
Beta Tubulin ◽  
Interacting Protein ◽  
Allele Specific ◽  
Extragenic Suppressors ◽  
Microtubule Function

We identified four mutations in two previously undescribed loci involved in microtubule function in Aspergillus nidulans as extragenic suppressors of benA33, a heat-sensitive beta-tubulin mutation. Three of the four mutations map to a locus closely linked to riboB on linkage group VIII; we designated this locus mipA (for microtubule-interacting protein). We were not able to map the remaining suppressor because of chromosomal rearrangements. However, since it recombines with riboB at a significantly higher frequency than the mipA alleles, it is unlikely to be in mipA; thus, we designated it mipB1. The mip mutations are not allelic to the previously identified loci that encode alpha- and beta-tubulin, and it is likely that mipA and mipB encode previously unidentified nontubulin proteins involved in microtubule function. Each of the mip mutations suppresses the heat sensitivity conferred by benA33 and suppresses the blockage of nuclear division and movement conferred by this mutation at high temperatures. Interactions between mipA and benA are allele specific. All of the mipA mutations are cryptic in a wild-type benA background but cause cold sensitivity in combination with benA33. These mutations also confer cold sensitivity in combination with benA31 and benA32 and reduce the resistance conferred by these mutations to the antimicrotubule agent benomyl but do not suppress the heat sensitivity conferred by these alleles. Finally, the mipA alleles suppress the heat sensitivity conferred by benA11, benA17, and benA21 but do not confer cold sensitivity in combination with these alleles.

scholarly journals CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae.

1993 ◽  
Vol 13 (8) ◽  
pp. 4691-4702 ◽  
Author(s):  
Z Xiao ◽  
J T McGrew ◽  
A J Schroeder ◽  
M Fitzgerald-Hayes
Keyword(s):  
Chromosome Segregation ◽  
Leucine Zipper ◽  
Mitotic Chromosome ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
New Genes ◽  
Marked Chromosome ◽  
Cold Sensitive ◽  
Basic Region ◽  
Segregation Of Chromosomes

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.

scholarly journals Isolation of mip (microtubule-interacting protein) mutations of Aspergillus nidulans

1986 ◽  
Vol 6 (8) ◽  
pp. 2963-2968
Author(s):  
C F Weil ◽  
C E Oakley ◽  
B R Oakley
Keyword(s):  
Aspergillus Nidulans ◽  
Chromosomal Rearrangements ◽  
Cold Sensitivity ◽  
Heat Sensitivity ◽  
Wild Type ◽  
Beta Tubulin ◽  
Interacting Protein ◽  
Allele Specific ◽  
Extragenic Suppressors ◽  
Microtubule Function

We identified four mutations in two previously undescribed loci involved in microtubule function in Aspergillus nidulans as extragenic suppressors of benA33, a heat-sensitive beta-tubulin mutation. Three of the four mutations map to a locus closely linked to riboB on linkage group VIII; we designated this locus mipA (for microtubule-interacting protein). We were not able to map the remaining suppressor because of chromosomal rearrangements. However, since it recombines with riboB at a significantly higher frequency than the mipA alleles, it is unlikely to be in mipA; thus, we designated it mipB1. The mip mutations are not allelic to the previously identified loci that encode alpha- and beta-tubulin, and it is likely that mipA and mipB encode previously unidentified nontubulin proteins involved in microtubule function. Each of the mip mutations suppresses the heat sensitivity conferred by benA33 and suppresses the blockage of nuclear division and movement conferred by this mutation at high temperatures. Interactions between mipA and benA are allele specific. All of the mipA mutations are cryptic in a wild-type benA background but cause cold sensitivity in combination with benA33. These mutations also confer cold sensitivity in combination with benA31 and benA32 and reduce the resistance conferred by these mutations to the antimicrotubule agent benomyl but do not suppress the heat sensitivity conferred by these alleles. Finally, the mipA alleles suppress the heat sensitivity conferred by benA11, benA17, and benA21 but do not confer cold sensitivity in combination with these alleles.

scholarly journals Extragenic suppressors of nudC3, a mutation that blocks nuclear migration in Aspergillus nidulans.

Genetics ◽  
1995 ◽  
Vol 141 (2) ◽  
pp. 453-464 ◽  
Author(s):  
Y H Chiu ◽  
N R Morris
Keyword(s):  
Aspergillus Nidulans ◽  
Normal Level ◽  
Growth And Development ◽  
Nuclear Migration ◽  
Cytoplasmic Dynein ◽  
Intracellular Concentration ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Extra Copy ◽  
Extragenic Suppressors

Abstract Nuclear migration plays an important role in the growth and development of many organisms including the filamentous fungus Aspergillus nidulans. We have cloned three genes from A. nidulans, nudA, nudC, and nudF, in which mutations affect nuclear migration. The nudA gene encodes the heavy chain of cytoplasmic dynein. The nudC gene encodes a 22-kD protein. The nudF gene was identified as an extra copy suppressor of the temperature sensitive (ts-) nudC3 mutation. The nudC3 mutation substantially decreases the intracellular concentration of the nudF protein at restrictive temperature. This is restored toward the normal level by an extra copy of nudF. To identify other genes whose products interact directly or indirectly with the NUDC protein, we have isolated a set of extragenic suppressors showed them to represent nine different genes, designated sncA-sncI (for suppressor of nudC). sncA-sncH were either dominant or semidominant in diploids homozygous for nudC3 and heterozygous for the snc mutations. All of the suppressors reversed the ts- phenotype of nudC3 by restoring the intracellular concentration of the NUDF protein.

Extragenic Suppressors of thenimX2cdc2Mutation ofAspergillus nidulansAffect Nuclear Division, Septation and Conidiation

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 1573-1584
Author(s):  
Sarah Lea McGuire ◽  
Dana L Roe ◽  
Brett W Carter ◽  
Robert L Carter ◽  
Sean P Grace ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Aspergillus Nidulans ◽  
Biochemical Analysis ◽  
Nuclear Division ◽  
Temperature Sensitive ◽  
Suppressor Genes ◽  
Suppressor Mutations ◽  
Cold Sensitive ◽  
Extragenic Suppressors

AbstractThe Aspergillus nidulans NIMXCDC2 protein kinase has been shown to be required for both the G2/M and G1/S transitions, and recent evidence has implicated a role for NIMXCDC2 in septation and conidiation. While much is understood of its G2/M function, little is known about the functions of NIMXCDC2 during G1/S, septation, and conidiophore development. In an attempt to better understand how NIMXCDC2 is involved in these processes, we have isolated four extragenic suppressors of the A. nidulans nimX2cdc2 temperature-sensitive mutation. Mutation of these suppressor genes, designated snxA-snxD for suppressor of nimX, affects nuclear division, septation, and conidiation. The cold-sensitive snxA1 mutation leads to arrest of nuclear division during G1 or early S. snxB1 causes hyperseptation in the hyphae and sensitivity to hydroxyurea, while snxC1 causes septation in the conidiophore stalk and aberrant conidiophore structure. snxD1 leads to slight septation defects and hydroxyurea sensitivity. The additional phenotypes that result from the suppressor mutations provide genetic evidence that NIMXCDC2 affects septation and conidiation in addition to nuclear division, and cloning and biochemical analysis of these will allow a better understanding of the role of NIMXCDC2 in these processes.

DBF8, an essential gene required for efficient chromosome segregation in Saccharomyces cerevisiae

1994 ◽  
Vol 14 (9) ◽  
pp. 6350-6360
Author(s):  
F Houman ◽  
C Holm
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Essential Gene ◽  
Chromosome Loss ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Nonsense Mutations ◽  
Carboxy Terminal

To investigate chromosome segregation in Saccharomyces cerevisiae, we examined a collection of temperature-sensitive mutants that arrest as large-budded cells at restrictive temperatures (L. H. Johnston and A. P. Thomas, Mol. Gen. Genet. 186:439-444, 1982). We characterized dbf8, a mutation that causes cells to arrest with a 2c DNA content and a short spindle. DBF8 maps to chromosome IX near the centromere, and it encodes a 36-kDa protein that is essential for viability at all temperatures. Mutational analysis reveals that three dbf8 alleles are nonsense mutations affecting the carboxy-terminal third of the encoded protein. Since all of these mutations confer temperature sensitivity, it appears that the carboxyl-terminal third of the protein is essential only at a restrictive temperature. In support of this conclusion, an insertion of URA3 at the same position also confers a temperature-sensitive phenotype. Although they show no evidence of DNA damage, dbf8 mutants exhibit increased rates of chromosome loss and nondisjunction even at a permissive temperature. Taken together, our data suggest that Dbf8p plays an essential role in chromosome segregation.

CDC55, a Saccharomyces cerevisiae gene involved in cellular morphogenesis: identification, characterization, and homology to the B subunit of mammalian type 2A protein phosphatase

1991 ◽  
Vol 11 (11) ◽  
pp. 5767-5780
Author(s):  
A M Healy ◽  
S Zolnierowicz ◽  
A E Stapleton ◽  
M Goebl ◽  
A A DePaoli-Roach ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Phosphatase ◽  
Protein A ◽  
Cdna Clones ◽  
Restrictive Temperature ◽  
B Subunit ◽  
Bud Emergence ◽  
New Gene ◽  
Cold Sensitive ◽  
Polymerase Chain

Microscopic screening of a collection of cold-sensitive mutants of Saccharomyces cerevisiae led to the identification of a new gene, CDC55, which appears to be involved in the morphogenetic events of the cell cycle. CDC55 maps between CDC43 and CHC1 on the left arm of chromosome VII. At restrictive temperature, the original cdc55 mutant produces abnormally elongated buds and displays a delay or partial block of septation and/or cell separation. A cdc55 deletion mutant displays a cold-sensitive phenotype like that of the original isolate. Sequencing of CDC55 revealed that it encodes a protein of about 60 kDa, as confirmed by Western immunoblots using Cdc55p-specific antibodies. This protein has greater than 50% sequence identity to the B subunits of rabbit skeletal muscle type 2A protein phosphatase; the latter sequences were obtained by analysis of peptides derived from the purified protein, a polymerase chain reaction product, and cDNA clones. An extragenic suppressor of the cdc55 mutation lies in BEM2, a gene previously identified on the basis of an apparent role in bud emergence.

bimA encodes a member of the tetratricopeptide repeat family of proteins and is required for the completion of mitosis in Aspergillus nidulans

1991 ◽  
Vol 99 (4) ◽  
pp. 711-719
Author(s):  
K.L. O'Donnell ◽  
A.H. Osmani ◽  
S.A. Osmani ◽  
N.R. Morris
Keyword(s):  
Amino Acid ◽  
Aspergillus Nidulans ◽  
Essential Gene ◽  
Tetratricopeptide Repeat ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Reading Frame ◽  
Integrative Transformation

The recessive, temperature-sensitive bimA1 mutation of Aspergillus nidulans blocks nuclei in metaphase at restrictive temperature. To determine whether the bimA product is essential, integrative transformation was used to create a mutation in the bimA gene. The mutation was maintained in a heterokaryon and the phenotype of spores produced by the heterokaryon was analyzed. Molecular disruption of the wild-type bimA gene is recessive in the heterokaryon and causes a metaphase block, demonstrating that bimA is an essential gene for mitosis. bimA was cloned by DNA-mediated complementation of its mutant phenotype at restrictive temperature, and the nucleotide sequence of a full-length cDNA was determined. A single large open reading frame was identified in the cDNA sequence, which predicts a protein containing 806 amino acid residues that is related (30.4% identity) to the Schizosaccharomyces pombe nuc2+ gene product, which also is required for completion of mitosis. The sequence of the bimA gene indicates that it is a member of a family of mostly nuclear proteins that contain a degenerate 34 amino acid repeat, the TPR (tetratricopeptide repeat) gene family.

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