scholarly journals Identification of a Second Myosin-II in Schizosaccharomyces pombe:

1997 ◽  
Vol 8 (12) ◽  
pp. 2693-2705 ◽  
Author(s):  
Magdalena Bezanilla ◽  
Susan L. Forsburg ◽  
Thomas D. Pollard
Keyword(s):  
Catalytic Domain ◽  
Myosin Ii ◽  
Growth Conditions ◽  
Actin Binding ◽  
Temperature Sensitive ◽  
Binding Motifs ◽  
Synthetic Lethal ◽  
Synthetic Lethal Interactions ◽  
Morphological Defects ◽  
Cold Sensitive

As in many eukaryotic cells, fission yeast cytokinesis depends on the assembly of an actin ring. We clonedmyp2+ , a myosin-II inSchizosaccharomyces pombe, conditionally required for cytokinesis. myp2+ , the second myosin-II identified in S. pombe, does not completely overlap in function with myo2+ . The catalytic domain of Myp2p is highly homologous to known myosin-IIs, and phylogenetic analysis places Myp2p in the myosin-II family. The Myp2p sequence contains well-conserved ATP- and actin-binding motifs, as well as two IQ motifs. However, the tail sequence is unusual, since it is predicted to form two long coiled-coils separated by a stretch of sequence containing 19 prolines. Disruption of myp2+ is not lethal but under nutrient limiting conditions cells lackingmyp2+ function are multiseptated, elongated, and branched, indicative of a defect in cytokinesis. The presence of salt enhances these morphological defects. Additionally,Δmyp2 cells are cold sensitive in high salt, failing to form colonies at 17°C. Thus, myp2+ is required under conditions of stress, possibly linking extracellular growth conditions to efficient cytokinesis and cell growth. GFP-Myp2p localizes to a ring in the middle of late mitotic cells, consistent with a role in cytokinesis. Additionally, we constructed double mutants of Δmyp2 with temperature-sensitive mutant strains defective in cytokinesis. We observed synthetic lethal interactions between Δmyp2 and three alleles ofcdc11ts, as well as more modest synthetic interactions with cdc14ts and cdc16ts, implicatingmyp2+ function for efficient cytokinesis under normal conditions.

scholarly journals Synthetic-lethal interactions identify two novel genes, SLA1 and SLA2, that control membrane cytoskeleton assembly in Saccharomyces cerevisiae

1993 ◽  
Vol 122 (3) ◽  
pp. 635-644 ◽  
Author(s):  
DA Holtzman ◽  
S Yang ◽  
DG Drubin
Keyword(s):  
Focal Adhesions ◽  
Null Alleles ◽  
Actin Binding ◽  
Temperature Sensitive ◽  
Cortical Actin ◽  
Synthetic Lethal ◽  
Amino Acid Region ◽  
New Genes ◽  
Membrane Cytoskeleton ◽  
Synthetic Lethal Interactions

Abplp is a yeast cortical actin-binding protein that contains an SH3 domain similar to those found in signal transduction proteins that function at the membrane/cytoskeleton interface. Although no detectable phenotypes are associated with a disruption allele of ABP1, mutations that create a requirement for this protein have now been isolated in the previously identified gene SAC6 and in two new genes, SLA1 and SLA2. The SAC6 gene encodes yeast fimbrin, an actin filament-bundling protein. Null mutations in SLA1 and SLA2 cause temperature-sensitive growth defects. Sla1p contains three SH3 domains and is essential for the proper formation of the cortical actin cytoskeleton. The COOH terminus of Sla2p contains a 200 amino acid region with homology to the COOH terminus of talin, a membrane cytoskeletal protein which is a component of fibroblast focal adhesions. Sla2p is required for cellular morphogenesis and polarization of the cortical cytoskeleton. In addition, synthetic-lethal interactions were observed for double-mutants containing null alleles of SLA2 and SAC6. In total, the mutant phenotypes, sequences, and genetic interactions indicate that we have identified novel proteins that cooperate to control the dynamic cytoskeletal rearrangements that are required for the development of cell polarity in budding yeast.

scholarly journals Evidence that the MIF2 gene of Saccharomyces cerevisiae encodes a centromere protein with homology to the mammalian centromere protein CENP-C.

1995 ◽  
Vol 6 (7) ◽  
pp. 793-807 ◽  
Author(s):  
P B Meluh ◽  
D Koshland
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Temperature Sensitive ◽  
Synthetic Lethal ◽  
Cis Acting ◽  
Centromere Protein ◽  
Synthetic Lethal Interactions ◽  
Dna Complex ◽  
Two Temperature ◽  
High Instability ◽  
Temperature Sensitive Phenotype

The MIF2 gene of Saccharomyces cerevisiae has been implicated in mitosis. Here we provide genetic evidence that MIF2 encodes a centromere protein. Specifically, we found that mutations in MIF2 stabilize dicentric minichromosomes and confer high instability (i.e., a synthetic acentric phenotype) to chromosomes that bear a cis-acting mutation in element I of the yeast centromeric DNA (CDEI). Similarly, we observed synthetic phenotypes between mutations in MIF2 and trans-acting mutations in three known yeast centromere protein genes-CEP1/CBF1/CPF1, NDC10/CBF2, and CEP3/CBF3B. In addition, the mif2 temperature-sensitive phenotype can be partially rescued by increased dosage of CEP1. Synthetic lethal interactions between a cep1 null mutation and mutations in either NDC10 or CEP3 were also detected. Taken together, these data suggest that the Mif2 protein interacts with Cep1p at the centromere and that the yeast centromere indeed exists as a higher order protein-DNA complex. The Mif2 and Cep1 proteins contain motifs of known transcription factors, suggesting that assembly of the yeast centromere is analogous to that of eukaryotic enhancers and origins of replication. We also show that the predicted Mif2 protein shares two short regions of homology with the mammalian centromere Ag CENP-C and that two temperature-sensitive mutations in MIF2 lie within these regions. These results provide evidence for structural conservation between yeast and mammalian centromeres.

scholarly journals High-Copy Suppressor Analysis Reveals a Physical Interaction between Sec34p and Sec35p, a Protein Implicated in Vesicle Docking

1999 ◽  
Vol 10 (10) ◽  
pp. 3317-3329 ◽  
Author(s):  
Dong-Wook Kim ◽  
Michael Sacher ◽  
Al Scarpa ◽  
Anne Marie Quinn ◽  
Susan Ferro-Novick
Keyword(s):  
Temperature Sensitive ◽  
Physical Interaction ◽  
Synthetic Lethal ◽  
Vesicle Docking ◽  
Vesicular Traffic ◽  
Golgi Transport ◽  
Synthetic Lethal Interactions ◽  
Golgi Protein ◽  
Late Stages ◽  
Suppressor Analysis

A temperature-sensitive mutant, sec34-2, is defective in the late stages of endoplasmic reticulum (ER)-to-Golgi transport. A high-copy suppressor screen that uses thesec34-2 mutant has resulted in the identification of theSEC34 structural gene and a novel gene calledGRP1. GRP1 encodes a previously unidentified hydrophilic yeast protein related to the mammalian Golgi protein golgin-160. Although GRP1 is not essential for growth, the grp1Δ mutation displays synthetic lethal interactions with several mutations that result in ER accumulation and a block in the late stages of ER-to-Golgi transport, but not with those that block the budding of vesicles from the ER. Our findings suggest that Grp1p may facilitate membrane traffic indirectly, possibly by maintaining Golgi function. In an effort to identify genes whose products physically interact with Sec34p, we also tested the ability of overexpressed SEC34 to suppress known secretory mutations that block vesicular traffic between the ER and the Golgi. This screen revealed that SEC34 specifically suppressessec35-1. SEC34 encodes a hydrophilic protein of ∼100 kDa. Like Sec35p, which has been implicated in the tethering of ER-derived vesicles to the Golgi, Sec34p is predominantly soluble. Sec34p and Sec35p stably associate with each other to form a multiprotein complex of ∼480 kDa. These data indicate that Sec34p acts in conjunction with Sec35p to mediate a common step in vesicular traffic.

scholarly journals Interactions between Centromere Complexes in Saccharomyces cerevisiae

2003 ◽  
Vol 14 (12) ◽  
pp. 4931-4946 ◽  
Author(s):  
Vladimir S. Nekrasov ◽  
Melanie A. Smith ◽  
Sew Peak-Chew ◽  
John V. Kilmartin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromatin Immunoprecipitation ◽  
Complex Structure ◽  
Protein A ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
The Other ◽  
Temperature Sensitive ◽  
Synthetic Lethal ◽  
Synthetic Lethal Interactions

We have purified two new complexes from Saccharomyces cerevisiae, one containing the centromere component Mtw1p together with Nnf1p, Nsl1p, and Dsn1p, which we call the Mtw1p complex, and the other containing Spc105p and Ydr532p, which we call the Spc105p complex. Further purifications using Dsn1p tagged with protein A show, in addition to the other components of the Mtw1p complex, the two components of the Spc105p complex and the four components of the previously described Ndc80p complex, suggesting that all three complexes are closely associated. Fluorescence microscopy and immunoelectron microscopy show that Nnf1p, Nsl1p, Dsn1p, Spc105p, and Ydr532p all localize to the nuclear side of the spindle pole body and along short spindles. Chromatin immunoprecipitation assays show that all five proteins are associated with centromere DNA. Homologues of Nsl1p and Spc105p in Schizosaccharomyces pombe also localize to the centromere. Temperature-sensitive mutations of Nsl1p, Dsn1p, and Spc105p all cause defects in chromosome segregation. Synthetic-lethal interactions are found between temperature-sensitive mutations in proteins from all three complexes, in agreement with their close physical association. These results show an increasingly complex structure for the S. cerevisiae centromere and a probable conservation of structure between parts of the centromeres of S. cerevisiae and S. pombe.

scholarly journals C-terminal truncations of the yeast nucleoporin Nup145p produce a rapid temperature-conditional mRNA export defect and alterations to nuclear structure.

1997 ◽  
Vol 17 (2) ◽  
pp. 906-920 ◽  
Author(s):  
T C Dockendorff ◽  
C V Heath ◽  
A L Goldstein ◽  
C A Snay ◽  
C N Cole
Keyword(s):  
Amino Acids ◽  
Nuclear Structure ◽  
Growth Conditions ◽  
Nuclear Accumulation ◽  
Nuclear Pore ◽  
Temperature Sensitive ◽  
Nucleocytoplasmic Trafficking ◽  
Synthetic Lethal ◽  
Acid Protein ◽  
Rapid Temperature

A screen for temperature-sensitive mutants of Saccharomyces cerevisiae defective in nucleocytoplasmic trafficking of poly(A)+ RNA has identified an allele of the NUP145 gene, which encodes an essential nucleoporin. NUP145 was previously identified by using a genetic synthetic lethal screen (E. Fabre, W. C. Boelens, C. Wimmer, I. W. Mattaj, and E. C. Hurt, Cell 78:275-289, 1994) and by using a monoclonal antibody which recognizes the GLFG family of vertebrate and yeast nucleoporins (S. R. Wente and G. Blobel, J. Cell Biol. 125:955-969, 1994). Cells carrying the new allele, nup145-10, grew at 23 and 30 degrees C but were unable to grow at 37 degrees C. Many cells displayed a modest accumulation of poly(A)+ RNA under permissive growth conditions, and all cells showed dramatic and rapid nuclear accumulation of poly(A)+ RNA following a shift to 37 degrees C. The mutant allele contains a nonsense codon which truncates the 1,317-amino-acid protein to 698 amino acids. This prompted us to examine the role of the carboxyl half of Nup145p. Several additional alleles that encode C-terminally truncated proteins or proteins containing internal deletions of portions of the carboxyl half of Nup145p were constructed. Analysis of these mutants indicates that some sequences between amino acids 698 and 1095 are essential for RNA export and for growth at 37 degrees C. In these strains, nuclear accumulation of poly(A)+ RNA and fragmentation of the nucleolus occurred rapidly following a shift to 37 degrees C. Constitutive defects in nuclear pore complex distribution and nuclear structure were also seen in these strains. Although cells lacking Nup145p grew extremely slowly at 23 degrees C and did not grow at 30 degrees C, efficient growth at 23 or 30 degrees C occurred as long as cells produced either the amino 58% or the carboxyl 53% of Nup145p. Strains carrying alleles of NUP145 lacking up to 200 amino acids from the carboxy terminus were viable at 37 degrees C but displayed nucleolar fragmentation and some nuclear accumulation of poly(A)+ RNA following a shift to 37 degrees C. Surprisingly, these strains grew efficiently at 37 degrees C in spite of a reduction in the level of synthesis of rRNAs to approximately 25% of the wild-type level.

Synthetic Lethal Interactions in Cancer Therapy

2017 ◽  
Vol 17 (4) ◽  
pp. 304-310 ◽  
Author(s):  
Xinwei Geng ◽  
Xiaohui Wang ◽  
Dan Zhu ◽  
Songmin Ying
Keyword(s):  
Cancer Therapy ◽  
Synthetic Lethal ◽  
Synthetic Lethal Interactions

scholarly journals A Genetic Analysis of Interactions with Spc110p Reveals Distinct Functions of Spc97p and Spc98p, Components of the Yeast γ-Tubulin Complex

1998 ◽  
Vol 9 (8) ◽  
pp. 2201-2216 ◽  
Author(s):  
Thu Nguyen ◽  
Dani B.N. Vinh ◽  
Douglas K. Crawford ◽  
Trisha N. Davis
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Amino Terminus ◽  
Temperature Sensitive ◽  
Microtubule Organizing Center ◽  
Synthetic Lethal ◽  
Lethal Phenotype ◽  
Amino Terminal ◽  
N Terminus ◽  
Two Hybrid

The spindle pole body (SPB) in Saccharomyces cerevisiae functions as the microtubule-organizing center. Spc110p is an essential structural component of the SPB and spans between the central and inner plaques of this multilamellar organelle. The amino terminus of Spc110p faces the inner plaque, the substructure from which spindle microtubules radiate. We have undertaken a synthetic lethal screen to identify mutations that enhance the phenotype of the temperature-sensitive spc110–221 allele, which encodes mutations in the amino terminus. The screen identified mutations inSPC97 and SPC98, two genes encoding components of the Tub4p complex in yeast. The spc98–63allele is synthetic lethal only with spc110 alleles that encode mutations in the N terminus of Spc110p. In contrast, thespc97 alleles are synthetic lethal withspc110 alleles that encode mutations in either the N terminus or the C terminus. Using the two-hybrid assay, we show that the interactions of Spc110p with Spc97p and Spc98p are not equivalent. The N terminus of Spc110p displays a robust interaction with Spc98p in two different two-hybrid assays, while the interaction between Spc97p and Spc110p is not detectable in one strain and gives a weak signal in the other. Extra copies of SPC98 enhance the interaction between Spc97p and Spc110p, while extra copies of SPC97interfere with the interaction between Spc98p and Spc110p. By testing the interactions between mutant proteins, we show that the lethal phenotype in spc98–63 spc110–221 cells is caused by the failure of Spc98–63p to interact with Spc110–221p. In contrast, the lethal phenotype in spc97–62 spc110–221 cells can be attributed to a decreased interaction between Spc97–62p and Spc98p. Together, these studies provide evidence that Spc110p directly links the Tub4p complex to the SPB. Moreover, an interaction between Spc98p and the amino-terminal region of Spc110p is a critical component of the linkage, whereas the interaction between Spc97p and Spc110p is dependent on Spc98p.

scholarly journals A Yeast taf17 Mutant Requires the Swi6 Transcriptional Activator for Viability and Shows Defects in Cell Cycle-Regulated Transcription

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1561-1576
Author(s):  
Neil Macpherson ◽  
Vivien Measday ◽  
Lynda Moore ◽  
Brenda Andrews
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Essential Gene ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Synthetic Lethal ◽  
Cycle Arrest ◽  
A Cell ◽  
Allelism Tests ◽  
Complementation Groups

Abstract In Saccharomyces cerevisiae, the Swi6 protein is a component of two transcription factors, SBF and MBF, that promote expression of a large group of genes in the late G1 phase of the cell cycle. Although SBF is required for cell viability, SWI6 is not an essential gene. We performed a synthetic lethal screen to identify genes required for viability in the absence of SWI6 and identified 10 complementation groups of swi6-dependent lethal mutants, designated SLM1 through SLM10. We were most interested in mutants showing a cell cycle arrest phenotype; both slm7-1 swi6Δ and slm8-1 swi6Δ double mutants accumulated as large, unbudded cells with increased 1N DNA content and showed a temperature-sensitive growth arrest in the presence of Swi6. Analysis of the transcript levels of cell cycle-regulated genes in slm7-1 SWI6 mutant strains at the permissive temperature revealed defects in regulation of a subset of cyclin-encoding genes. Complementation and allelism tests showed that SLM7 is allelic with the TAF17 gene, which encodes a histone-like component of the general transcription factor TFIID and the SAGA histone acetyltransferase complex. Sequencing showed that the slm7-1 allele of TAF17 is predicted to encode a version of Taf17 that is truncated within a highly conserved region. The cell cycle and transcriptional defects caused by taf17slm7-1 are consistent with the role of TAFIIs as modulators of transcriptional activation and may reflect a role for TAF17 in regulating activation by SBF and MBF.

scholarly journals Combinatorial CRISPR screen identifies fitness effects of gene paralogues

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nicola A. Thompson ◽  
Marco Ranzani ◽  
Louise van der Weyden ◽  
Vivek Iyer ◽  
Victoria Offord ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Cell Lines ◽  
Unknown Function ◽  
Single Copy ◽  
Genetic Redundancy ◽  
Synthetic Lethal ◽  
Fitness Effects ◽  
Synthetic Lethal Interactions ◽  
Crispr Screen ◽  
Multiple Cell

AbstractGenetic redundancy has evolved as a way for human cells to survive the loss of genes that are single copy and essential in other organisms, but also allows tumours to survive despite having highly rearranged genomes. In this study we CRISPR screen 1191 gene pairs, including paralogues and known and predicted synthetic lethal interactions to identify 105 gene combinations whose co-disruption results in a loss of cellular fitness. 27 pairs influence fitness across multiple cell lines including the paralogues FAM50A/FAM50B, two genes of unknown function. Silencing of FAM50B occurs across a range of tumour types and in this context disruption of FAM50A reduces cellular fitness whilst promoting micronucleus formation and extensive perturbation of transcriptional programmes. Our studies reveal the fitness effects of FAM50A/FAM50B in cancer cells.

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