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.

Septum formation in Aspergillus nidulans

1995 ◽  
Vol 73 (S1) ◽  
pp. 396-399 ◽  
Author(s):  
Michelle Momany ◽  
Jennifer L. Morrell ◽  
Steven D. Harris ◽  
John E. Hamer
Keyword(s):  
Aspergillus Nidulans ◽  
Antibody Production ◽  
Nuclear Division ◽  
Temperature Sensitive ◽  
Cellular Processes ◽  
The Third ◽  
Septum Formation ◽  
Chromosome Transmission ◽  
Insight Into

We are investigating septation in Aspergillus nidulans. We have shown that septum formation is dependent on the third nuclear division and actin is involved in this process. We have also characterized nine temperature-sensitive septation (sep) mutants. On the basis of our analysis we have divided these mutants into three phenotypic classes. We are uncovering the order of events in the septation pathway by analysis of double mutants constructed with different pairs of sep mutants. The sepB gene has been cloned and sequenced. Homology with the Saccharomyces cerevisiae CTF4 gene and the phenotype of the sepB mutant support a role in monitoring the fidelity of chromosome transmission. We are also investigating the role of the asp genes (Aspergillus septins). Three asp genes were identified by homology with the S. cerevisiae septins. aspB has been cloned, sequenced, and fused to a biotinylated tag for antibody production. Antibody production and localization studies are now underway. Because septation requires the integration of several cellular processes, our studies should give insight into the cell cycle, cell wall biosnythesis and development of A. nidulans. Key words: septation, cytokinesis, 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.

scholarly journals Pseudoreversion analysis indicates a direct role of cell division genes in polar morphogenesis and differentiation in Caulobacter crescentus.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 623-630 ◽  
Author(s):  
J M Sommer ◽  
A Newton
Keyword(s):  
Cell Division ◽  
Caulobacter Crescentus ◽  
Temperature Sensitive ◽  
Sensitive Cell ◽  
Direct Role ◽  
Pleiotropic Gene ◽  
Cold Sensitive ◽  
Extragenic Suppressors ◽  
Pleiotropic Mutation

Abstract A pseudoreversion analysis was used to examine the role of cell division genes in polar morphogenesis in Caulobacter crescentus. Extragenic suppressors of temperature sensitive mutations in pleC, a pleiotropic gene required for cell motility, formation of polar phi CbK bacteriophage receptors, and stalk formation, were isolated. These suppressors, which restored motility at 37 degrees C, simultaneously conferred a cold sensitive cell division phenotype and they were mapped to the three new cell division genes divJ, divL and divK. The cold-sensitive mutations in divL, and to a lesser extent divJ, exhibited a relatively narrow range of suppression. The cold-sensitive cell division mutation in divK, by contrast, suppressed all pleC mutations examined and behaved as a classical bypass suppressor. The direct role of this cell division gene in the regulation of motility is suggested by the observation that divK341 mapped to the same locus as pleD301, a pleiotropic mutation that prevents loss of motility and stalk formation. These results provide strong evidence that the cell division and developmental pathways are interconnected and they support our earlier conclusion that cell division is required for the regulation of polar morphogenesis and differentiation in C. crescentus.

scholarly journals Evidence for an Essential Catalytic Role of the F10 Protein Kinase in Vaccinia Virus Morphogenesis

2004 ◽  
Vol 78 (1) ◽  
pp. 257-265 ◽  
Author(s):  
Patricia Szajner ◽  
Andrea S. Weisberg ◽  
Bernard Moss
Keyword(s):  
Protein Kinase ◽  
Vaccinia Virus ◽  
Early Stage ◽  
Single Amino Acid ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Membrane Formation ◽  
Virus Morphogenesis ◽  
Catalytic Role

ABSTRACT Temperature-sensitive mutants of vaccinia virus, with genetic changes that map to the open reading frame encoding the F10 protein kinase, exhibit a defect at an early stage of viral morphogenesis. To further study the role of the enzyme, we constructed recombinant vaccinia virus vF10V5i, which expresses inducible V5 epitope-tagged F10 and is dependent on a chemical inducer for plaque formation and replication. In the absence of inducer, viral membrane formation was delayed and crescents and occasional immature forms were detected only late in infection. When the temperature was raised from 37 to 39°C, the block in membrane formation persisted throughout the infection. The increased stringency may be explained by a mild temperature sensitivity of the wild-type F10 kinase, which reduced the activity of the very small amount expressed in the absence of inducer, or by the thermolability of an unphosphorylated kinase substrate or uncomplexed F10-interacting protein. Further analyses demonstrated that tyrosine and threonine phosphorylation of the A17 membrane component was inhibited in the absence of inducer. The phosphorylation defect could be overcome by transfection of plasmids that express wild-type F10, but not by plasmids that express F10 with single amino acid substitutions that abolished catalytic activity. Although the mutated forms of F10 were stable and concentrated in viral factories, only the wild-type protein complemented the assembly and replication defects of vF10V5i in the absence of inducer. These studies provide evidence for an essential catalytic role of the F10 kinase in vaccinia virus morphogenesis.

scholarly journals Second-site suppressors of a cold-sensitive prohead accessory protein of bacteriophage phi X174.

Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 663-671 ◽  
Author(s):  
B A Fane ◽  
M Hayashi
Keyword(s):  
Liquid Culture ◽  
Acid Sites ◽  
Accessory Protein ◽  
Temperature Sensitive ◽  
Accessory Proteins ◽  
Wild Type ◽  
Major Coat Protein ◽  
Suppressor Mutations ◽  
Resistant Phenotype ◽  
Cold Sensitive

Abstract This study describes the isolation of second-site suppressors which correct for the defects associated with cold-sensitive (cs) prohead accessory proteins of bacteriophage phi X174. Five phenotypically different suppressors were isolated. Three of these suppressors confer novel temperature-sensitive (ts) phenotypes. They were unable to complement a ts mutation in gene F which encodes the major coat protein of the phage. All five suppressor mutations confer nucleotide changes in the gene F DNA sequence. These changes define four amino acid sites in the gene F protein. Three suppressor mutations placed into an otherwise wild-type background display a cold resistant phenotype in liquid culture infections when compared to a wild-type phi X174 control.

scholarly journals Cell division in Aspergillus

1992 ◽  
Vol 103 (3) ◽  
pp. 599-611 ◽  
Author(s):  
J.H. Doonan
Keyword(s):  
Cell Division ◽  
Aspergillus Nidulans ◽  
Molecular Analysis ◽  
Filamentous Fungus ◽  
Nuclear Division ◽  
Mutational Analysis ◽  
Cytoskeletal Proteins ◽  
Nuclear Movement ◽  
Cellular Analysis

Amenable to sophisticated genetic and molecular analysis, the simple filamentous fungus Aspergillus nidulans has provided some novel insights into the mechanisms and regulation of cell division. Mutational analysis has identified over fifty genes necessary for nuclear division, nuclear movement and cytokinesis. Molecular and cellular analysis of these mutants has led to the discovery of novel components of the cytoskeleton as well as to clarifying the role of established cytoskeletal proteins. Mutations leading to defects in the kinases (i.e. p34cdc2) and phosphatases (i.e. cdc25 and PP1), which are known to regulate mitosis in other eukaryotes, have been identified in Aspergillus. Additional, as yet novel, mitotic regulatory molecules, encoded by the nimA and bimE genes, have also been discovered in Aspergillus.

MDS1, a dosage suppressor of an mck1 mutant, encodes a putative yeast homolog of glycogen synthase kinase 3

1994 ◽  
Vol 14 (1) ◽  
pp. 831-839
Author(s):  
J W Puziss ◽  
T A Hardy ◽  
R B Johnson ◽  
P J Roach ◽  
P Hieter
Keyword(s):  
Protein Kinase ◽  
Copy Number ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
High Copy Number ◽  
Glycogen Synthase Kinase 3 ◽  
Temperature Sensitive ◽  
Protein Kinase Activity ◽  
Nucleotide Sequence Data ◽  
Cold Sensitive

The yeast gene MCK1 encodes a serine/threonine protein kinase that is thought to function in regulating kinetochore activity and entry into meiosis. Disruption of MCK1 confers a cold-sensitive phenotype, a temperature-sensitive phenotype, and sensitivity to the microtubule-destabilizing drug benomyl and leads to loss of chromosomes during growth on benomyl. A dosage suppression selection was used to identify genes that, when present at high copy number, could suppress the cold-sensitive phenotype of mck1::HIS3 mutant cells. Several unique classes of clones were identified, and one of these, designated MDS1, has been characterized in some detail. Nucleotide sequence data reveal that MDS1 encodes a serine/threonine protein kinase that is highly homologous to the shaggy/zw3 kinase in Drosophila melanogaster and its functional homolog, glycogen synthase kinase 3, in rats. The presence of MDS1 in high copy number rescues both the cold-sensitive and the temperature-sensitive phenotypes, but not the benomyl-sensitive phenotype, associated with the disruption of MCK1. Analysis of strains harboring an mds1 null mutation demonstrates that MDS1 is not essential during normal vegetative growth but appears to be required for meiosis. Finally, in vitro experiments indicate that the proteins encoded by both MCK1 and MDS1 possess protein kinase activity with substrate specificity similar to that of mammalian glycogen synthase kinase 3.

scholarly journals Efficient Chromosome Biorientation and the Tension Checkpoint in Saccharomyces cerevisiae both Require Bir1

2009 ◽  
Vol 29 (16) ◽  
pp. 4552-4562 ◽  
Author(s):  
Vasso Makrantoni ◽  
Michael J. R. Stark
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Chromosome Segregation ◽  
Temperature Sensitive ◽  
Protein Kinase Activity ◽  
Restrictive Temperature ◽  
Microtubule Depolymerization ◽  
Spindle Poles ◽  
Sister Kinetochore

ABSTRACT Accurate chromosome segregation requires the capture of sister kinetochores by microtubules from opposite spindle poles prior to the initiation of anaphase, a state termed chromosome biorientation. In the budding yeast Saccharomyces cerevisiae, the conserved protein kinase Ipl1 (Aurora B in metazoans) is critical for ensuring correct chromosomal alignment. Ipl1 associates with its activators Sli15 (INCENP), Nbl1 (Borealin), and Bir1 (Survivin), but while Sli15 clearly functions with Ipl1 to promote chromosome biorientation, the role of Bir1 has been uncertain. Using a temperature-sensitive bir1 mutant (bir1-17), we show that Bir1 is needed to permit efficient chromosome biorientation. However, once established, chromosome biorientation is maintained in bir1-17 cells at the restrictive temperature. Ipl1 is partially delocalized in bir1-17 cells, and its protein kinase activity is markedly reduced under nonpermissive conditions. bir1-17 cells arrest normally in response to microtubule depolymerization but fail to delay anaphase when sister kinetochore tension is reduced. Thus, Bir1 is required for the tension checkpoint. Despite their robust mitotic arrest in response to nocodazole, bir1-17 cells are hypersensitive to microtubule-depolymerizing drugs and show a more severe biorientation defect on recovery from nocodazole treatment. The role of Bir1 therefore may become more critical when spindle formation is delayed.

scholarly journals MDS1, a dosage suppressor of an mck1 mutant, encodes a putative yeast homolog of glycogen synthase kinase 3.

1994 ◽  
Vol 14 (1) ◽  
pp. 831-839 ◽  
Author(s):  
J W Puziss ◽  
T A Hardy ◽  
R B Johnson ◽  
P J Roach ◽  
P Hieter
Keyword(s):  
Protein Kinase ◽  
Copy Number ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
High Copy Number ◽  
Glycogen Synthase Kinase 3 ◽  
Temperature Sensitive ◽  
Protein Kinase Activity ◽  
Nucleotide Sequence Data ◽  
Cold Sensitive

The yeast gene MCK1 encodes a serine/threonine protein kinase that is thought to function in regulating kinetochore activity and entry into meiosis. Disruption of MCK1 confers a cold-sensitive phenotype, a temperature-sensitive phenotype, and sensitivity to the microtubule-destabilizing drug benomyl and leads to loss of chromosomes during growth on benomyl. A dosage suppression selection was used to identify genes that, when present at high copy number, could suppress the cold-sensitive phenotype of mck1::HIS3 mutant cells. Several unique classes of clones were identified, and one of these, designated MDS1, has been characterized in some detail. Nucleotide sequence data reveal that MDS1 encodes a serine/threonine protein kinase that is highly homologous to the shaggy/zw3 kinase in Drosophila melanogaster and its functional homolog, glycogen synthase kinase 3, in rats. The presence of MDS1 in high copy number rescues both the cold-sensitive and the temperature-sensitive phenotypes, but not the benomyl-sensitive phenotype, associated with the disruption of MCK1. Analysis of strains harboring an mds1 null mutation demonstrates that MDS1 is not essential during normal vegetative growth but appears to be required for meiosis. Finally, in vitro experiments indicate that the proteins encoded by both MCK1 and MDS1 possess protein kinase activity with substrate specificity similar to that of mammalian glycogen synthase kinase 3.

Sign in / Sign up

Export Citation Format

Share Document