scholarly journals The Saccharomyces cerevisiae actin-related protein Arp2 is involved in the actin cytoskeleton.

1996 ◽  
Vol 134 (1) ◽  
pp. 117-132 ◽  
Author(s):  
V Moreau ◽  
A Madania ◽  
R P Martin ◽  
B Winson
Keyword(s):  
Actin Cytoskeleton ◽  
Genetic Interaction ◽  
Lucifer Yellow ◽  
Temperature Sensitive ◽  
Related Protein ◽  
Gene Encoding ◽  
Membrane Growth ◽  
Mutant Phenotypes ◽  
Mutant Cells

Arp2p is an essential yeast actin-related protein. Disruption of the corresponding ARP2 gene leads to a terminal phenotype characterized by the presence of a single large bud. Thus, Arp2p may be important for a late stage of the cell cycle (Schwob, E., and R.P. Martin, 1992. Nature (Lond.). 355:179-182). We have localized Arp2p by indirect immunofluorescence. Specific peptide antibodies revealed punctate staining under the plasma membrane, which partially colocalizes with actin. Temperature-sensitive arp2 mutations were created by PCR mutagenesis and selected by an ade2/SUP11 sectoring screen. One temperature-sensitive mutant that was characterized, arp2-H330L, was osmosensitive and had an altered actin cytoskeleton at a nonpermissive temperature, suggesting a role of Arp2p in the actin cytoskeleton. Random budding patterns were observed in both haploid and diploid arp2-H330L mutant cells. Endocytosis, as judged by Lucifer yellow uptake, was severely reduced in the mutant, at all temperatures. In addition, genetic interaction was observed between temperature-sensitive alleles arp2-H330L and cdc10-1. CDC10 is a gene encoding a neck filament-associated protein that is necessary for polarized growth and cytokinesis. Overall, the immunolocalization, mutant phenotypes, and genetic interaction suggest that the Arp2 protein is an essential component of the actin cytoskeleton that is involved in membrane growth and polarity, as well as in endocytosis.

scholarly journals Dictyostelium IQGAP-related Protein Specifically Involved in the Completion of Cytokinesis

1997 ◽  
Vol 137 (4) ◽  
pp. 891-898 ◽  
Author(s):  
Hiroyuki Adachi ◽  
Yasuhiro Takahashi ◽  
Takeshi Hasebe ◽  
Mikako Shirouzu ◽  
Shigeyuki Yokoyama ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Mass ◽  
Normal Growth ◽  
Time Lapse ◽  
Giant Cells ◽  
Small Gtpases ◽  
Related Protein ◽  
Gene Encoding ◽  
Daughter Cells ◽  
Considerable Homology

The gapA gene encoding a novel RasGTPase-activating protein (RasGAP)–related protein was found to be disrupted in a cytokinesis mutant of Dictyostelium that grows as giant and multinucleate cells in a dish culture. The predicted sequence of the GAPA protein showed considerable homology to those of Gap1/Sar1 from fission yeast and the COOH-terminal half of mammalian IQGAPs, the similarity extending beyond the RasGAP-related domain. In suspension culture, gapA− cells showed normal growth in terms of the increase in cell mass, but cytokinesis inefficiently occurred to produce spherical giant cells. Time-lapse recording of the dynamics of cell division in a dish culture revealed that, in the case of gapA− cells, cytokinesis was very frequently reversed at the step in which the midbody connecting the daughter cells should be severed. Earlier steps of cytokinesis in the gapA− cells seemed to be normal, since myosin II was accumulated at the cleavage furrow. Upon starvation, gapA− cells developed and formed fruiting bodies with viable spores, like the wild-type cells. These results indicate that the GAPA protein is specifically involved in the completion of cytokinesis. Recently, it was reported that IQGAPs are putative effectors for Rac and CDC42, members of the Rho family of GTPases, and participate in reorganization of the actin cytoskeleton. Thus, it is possible that Dictyostelium GAPA participates in the severing of the midbody by regulating the actin cytoskeleton through an interaction with a member of small GTPases.

scholarly journals The Schizosaccharomyces pombe dim1+ Gene Interacts with the Anaphase-Promoting Complex or Cyclosome (APC/C) Component lid1+ and Is Required for APC/C Function

1999 ◽  
Vol 19 (4) ◽  
pp. 2535-2546 ◽  
Author(s):  
Lynne D. Berry ◽  
Anna Feoktistova ◽  
Melanie D. Wright ◽  
Kathleen L. Gould
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Chromosome Segregation ◽  
State Level ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Anaphase Promoting Complex ◽  
Synthetic Lethal ◽  
C Complex ◽  
Mutant Cells

ABSTRACT The Schizosaccharomyces pombe dim1 + gene is required for entry into mitosis and for chromosome segregation during mitosis. To further understand dim1p function, we undertook a synthetic lethal screen with the temperature-sensitive dim1-35 mutant and isolated lid (for lethal in dim1-35) mutants. Here, we describe the temperature-sensitive lid1-6mutant. At the restrictive temperature of 36°C, lid1-6mutant cells arrest with a “cut” phenotype similar to that ofcut4 and cut9 mutants. An epitope-tagged version of lid1p is a component of a multiprotein ∼20S complex; the presence of lid1p in this complex depends upon functionalcut9 +. lid1p-myc coimmunoprecipitates with several other proteins, including cut9p and nuc2p, and the presence of cut9p in a 20S complex depends upon the activity oflid1 +. Further, lid1 +function is required for the multiubiquitination of cut2p, an anaphase-promoting complex or cyclosome (APC/C) target. Thus, lid1p is a component of the S. pombe APC/C. In dim1mutants, the abundances of lid1p and the APC/C complex decline significantly, and the ubiquitination of an APC/C target is abolished. These data suggest that at least one role of dim1p is to maintain or establish the steady-state level of the APC/C.

scholarly journals Genome analysis of American minks reveals link of mutations in Ras-related protein-38 gene to Moyle brown coat phenotype

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andrey D. Manakhov ◽  
Maria Yu. Mintseva ◽  
Igor A. Andreev ◽  
Lev I. Uralsky ◽  
Tatiana V. Andreeva ◽  
...  
Keyword(s):  
Genome Sequencing ◽  
American Mink ◽  
Whole Genome ◽  
Related Protein ◽  
Hair Colour ◽  
Gene Encoding ◽  
Breeding Programmes ◽  
Wide Group ◽  
Colour Variety

Abstract Over 35 fur colours have been described in American mink (Neovison vison), only six of which have been previously linked to specific genes. Moyle fur colour belongs to a wide group of brownish colours that are highly similar to each other, which complicates selection and breeding procedures. We performed whole genome sequencing for two American minks with Moyle (m/m) and Violet (a/a m/m /p/p) phenotypes. We identified two frame-shift mutations in the gene encoding Ras-related protein-38 (RAB38), which regulates the trafficking of tyrosinase-containing vesicles to maturing melanosomes. The results highlight the role of RAB38 in the biogenesis of melanosomes and melanin and the genetic mechanism contributing to hair colour variety and intensity. These data are also useful for tracking economically valuable fur traits in mink breeding programmes.

pipsqueak, an early acting member of the posterior group of genes, affects vasa level and germ cell-somatic cell interaction in the developing egg chamber

Development ◽  
1993 ◽  
Vol 119 (4) ◽  
pp. 1187-1202 ◽  
Author(s):  
V. Siegel ◽  
T.A. Jongens ◽  
L.Y. Jan ◽  
Y.N. Jan
Keyword(s):  
Pattern Formation ◽  
Genetic Interaction ◽  
Cell Interaction ◽  
Multiple Alleles ◽  
Posterior Group ◽  
Molecular Studies ◽  
Egg Chamber ◽  
Mutant Phenotypes

We have identified a new member of the posterior group of genes, which we call pipsqueak. We show that pipsqueak acts after the establishment of the oskar posterior anchor but before the localization of vasa protein during oogenesis. Characterization of multiple alleles at the pipsqueak locus shows that pipsqueak, like vasa, is required for early stages of oogenesis, including but not limited to formation of the egg chamber and progression through Stage 6 of oogenesis. Genetic interaction studies suggest that pipsqueak acts at least partially through vasa; molecular studies indicate that pipsqueak affects vasa level in the ovary. We compare vasa and pipsqueak mutant phenotypes in order to determine whether pipsqueak acts solely through vasa, and present a model for the role of pipsqueak in posterior pattern formation.

scholarly journals Incubation at the nonpermissive temperature induces deficiencies in UV resistance and mutagenesis in mouse mutant cells expressing a temperature-sensitive ubiquitin-activating enzyme (E1).

1997 ◽  
Vol 17 (3) ◽  
pp. 1484-1489 ◽  
Author(s):  
H Ikehata ◽  
S Kaneda ◽  
F Yamao ◽  
T Seno ◽  
T Ono ◽  
...  
Keyword(s):  
Dna Repair ◽  
Mammalian Cells ◽  
Uv Light ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Nonpermissive Temperature ◽  
Conjugation System ◽  
Ubiquitin Conjugating Enzyme ◽  
Mutant Phenotypes ◽  
Mutant Cells

In temperature-sensitive (ts) mutants of mouse FM3A cells, the levels of mutagenesis and survival of cells treated with DNA-damaging agents have been difficult to assess because they are killed after their mutant phenotypes are expressed at the nonpermissive temperature. To avoid this difficulty, we incubated the ts mutant cells at the restrictive temperature, 39 degrees C, for only a limited period after inducing DNA damage. We used ts mutants defective in genes for ubiquitin-activating enzyme (E1), DNA polymerase alpha, and p34(cdc2) kinase. Whereas the latter two showed no effect, E1 mutants were sensitized remarkably to UV light if incubated at 39 degrees C for limited periods after UV exposure. Eighty-five percent of the sensitization occurred within the first 12 h of incubation at 39 degrees C, and more than 36 h at 39 degrees C did not produce any further sensitization. Moreover, while the 39 degrees C incubation gave E1 mutants a moderate spontaneous mutator phenotype, the same treatment significantly diminished the level of UV-induced 6-thioguanine resistance mutagenesis and extended the time necessary for expression of the mutation phenotype. These characteristics of E1 mutants are reminiscent of the defective DNA repair phenotypes of Saccharomyces cerevisiae rad6 mutants, which have defects in a ubiquitin-conjugating enzyme (E2), to which E1 is known to transfer ubiquitin. These results demonstrate the involvement of E1 in eukaryotic DNA repair and mutagenesis and provide the first direct evidence that the ubiquitin-conjugation system contributes to DNA repair in mammalian cells.

scholarly journals Cortactin signalling and dynamic actin networks

2004 ◽  
Vol 382 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Roger J. DALY
Keyword(s):  
Tyrosine Kinase ◽  
Actin Cytoskeleton ◽  
Current Knowledge ◽  
Actin Binding ◽  
Related Protein ◽  
Protein Targets ◽  
Actin Networks ◽  
Multiple Protein ◽  
Initial Characterization

Cortactin was first identified over a decade ago, and its initial characterization as both an F-actin binding protein and v-Src substrate suggested that it was likely to be a key regulator of actin rearrangements in response to tyrosine kinase signalling. The recent discovery that cortactin binds and activates the actin related protein (Arp)2/3 complex, and thus regulates the formation of branched actin networks, together with the identification of multiple protein targets of the cortactin SH3 domain, have revealed diverse cellular roles for this protein. This article reviews current knowledge regarding the role of cortactin in signalling to the actin cytoskeleton in the context of these developments.

scholarly journals CRISPR/Cas9-mediated deletion of the Wiskott-Aldrich syndrome locus causes actin cytoskeleton disorganization in murine erythroleukemia cells

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6284
Author(s):  
Vanessa Fernández-Calleja ◽  
María-José Fernández-Nestosa ◽  
Pablo Hernández ◽  
Jorge B. Schvartzman ◽  
Dora B. Krimer
Keyword(s):  
Actin Cytoskeleton ◽  
Genomic Region ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Wiskott Aldrich Syndrome ◽  
Erythroleukemia Cells ◽  
Murine Erythroleukemia ◽  
Actin Protein ◽  
Murine Erythroleukemia Cells

Wiskott-Aldrich syndrome (WAS) is a recessive X-linked inmmunodeficiency caused by loss-of-function mutations in the gene encoding the WAS protein (WASp). WASp plays an important role in the polymerization of the actin cytoskeleton in hematopoietic cells through activation of the Arp2/3 complex. In a previous study, we found that actin cytoskeleton proteins, including WASp, were silenced in murine erythroleukemia cells defective in differentiation. Here, we designed a CRISPR/Cas9 strategy to delete a 9.5-kb genomic region encompassing theWasgene in the X chromosome of murine erythroleukemia (MEL) cells. We show thatWas-deficient MEL cells have a poor organization of the actin cytoskeleton that can be recovered by restoringWasexpression. We found that whereas the total amount of actin protein was similar between wild-type andWasknockout MEL cells, the latter exhibited an altered ratio of monomeric G-actin to polymeric F-actin. We also demonstrate thatWasoverexpression can mediate the activation of Bruton’s tyrosine kinase. Overall, these findings support the role of WASp as a key regulator of F-actin in erythroid cells.

scholarly journals Genetic interaction of the SMC complex with topoisomerase IV in Bacillus subtilis

Microbiology ◽  
2005 ◽  
Vol 151 (11) ◽  
pp. 3729-3737 ◽  
Author(s):  
Serkalem Tadesse ◽  
Judita Mascarenhas ◽  
Bernd Kösters ◽  
Andrej Hasilik ◽  
Peter L. Graumann
Keyword(s):  
Protein Synthesis ◽  
Genetic Interaction ◽  
Dual Function ◽  
Topoisomerase Iv ◽  
Global Protein Synthesis ◽  
Genetic Level ◽  
Negative Supercoiling ◽  
Structural Maintenance Of Chromosomes ◽  
Mutant Cells

The role of topoisomerase IV (Topo IV) and of the structural maintenance of chromosomes (SMC) complex in chromosome compaction and in global protein synthesis was investigated. Lowering of the levels of Topo IV led to chromosome decondensation, while overproduction induced chromosome hyper-compaction, showing that Topo IV has an influence on the compaction of the whole chromosome, in a manner similar to that of the SMC protein, though different in mechanism. Increased synthesis of Topo IV in smc-deleted cells partially rescued the growth and condensation defect of the deletion, but not the segregation defect, revealing that the two systems interact at a genetic level. Two-dimensional gel investigations showed that global protein synthesis is highly aberrant in smc-deleted cells, and, to a different extent, also in cells lacking ScpA or ScpB, which form the SMC complex together with SMC protein. Overproduction of Topo IV partially rescued the defect in protein synthesis in smc mutant cells, indicating that Topo IV can restore the loss of negative supercoiling caused by the absence of SMC protein, but does not fully rescue the segregation defect. The data also show that the SMC protein has a dual function, in chromosome supercoiling and in active segregation.

scholarly journals Iqg1p, a Yeast Homologue of the Mammalian IQGAPs, Mediates Cdc42p Effects on the Actin Cytoskeleton

1998 ◽  
Vol 142 (2) ◽  
pp. 443-455 ◽  
Author(s):  
Mahasin A. Osman ◽  
Richard A. Cerione
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Shape ◽  
Temperature Sensitive ◽  
Cellular Functions ◽  
Multinucleated Cells ◽  
Cell Biol ◽  
Pheromone Signaling ◽  
Regulatory Effects ◽  
Mutant Cells ◽  
Two Hybrid

The Rho-type GTPase Cdc42p has been implicated in diverse cellular functions including cell shape, cell motility, and cytokinesis, all of which involve the reorganization of the actin cytoskeleton. Targets of Cdc42p that interface the actin cytoskeleton are likely candidates for mediating cellular activities. In this report, we identify and characterize a yeast homologue for the mammalian IQGAP, a cytoskeletal target for Cdc42p. The yeast IQGAP homologue, designated Iqg1p, displays a two-hybrid interaction with activated Cdc42p and coimmunoprecipitates with actin filaments. Deletion of IQG1 results in a temperature-sensitive lethality and causes aberrant morphologies including elongated and round multinucleated cells. This together with its localization at the mother–bud neck, suggest that Iqg1p promotes budding and cytokinesis. At restrictive temperatures, the vacuoles of the mutant cells enlarge and vesicles accumulate in the bud. Interestingly, Iqg1p shows two-hybrid interactions with the ankyrin repeat–containing protein, Akr1p (Kao, L.-R., J. Peterson, J. Ruiru, L. Bender, and A. Bender. 1996. Mol. Cell. Biol. 16:168–178), which inhibits pheromone signaling and appears to promote cytokinesis and/or trafficking. We also show two-hybrid interactions between Iqg1p and Afr1p, a septin-binding protein involved in projection formation (Konopka, J.B., C. DeMattei, and C. Davis. 1995. Mol. Cell. Biol. 15:723–730). We propose that Iqg1p acts as a scaffold to recruit and localize a protein complex involved in actin-based cellular functions and thus mediates the regulatory effects of Cdc42p on the actin cytoskeleton.

scholarly journals A DedA Family Membrane Protein in Indium Extrusion in Rhodanobacter sp. B2A1Ga4

2021 ◽  
Vol 12 ◽  
Author(s):  
Joana B. Caldeira ◽  
Ana Paula Chung ◽  
Ana Paula Piedade ◽  
Paula V. Morais ◽  
Rita Branco
Keyword(s):  
Negative Impact ◽  
High Tech ◽  
Gene Encoding ◽  
High Accumulation ◽  
Native Strain ◽  
Critical Metal ◽  
Family Protein ◽  
Cellular Metabolic Activity ◽  
Mutant Cells

Indium (In) is a critical metal widely used in electronic equipment, and the supply of this precious metal is a major challenge for sustainable development. The use of microorganisms for the recovery of this critical high-tech element has been considered an excellent eco-friendly strategy. The Rhodanobacter sp. B2A1Ga4 strain, highly resistant to In, was studied in order to disclose the bacterial mechanisms closely linked to the ability to cope with this metal. The mutation of the gene encoding for a DedA protein homolog, YqaA, affected drastically the In resistance and the cellular metabolic activity of strain Rhodanobacter sp. B2A1Ga4 in presence of this metal. This indicates that this protein plays an important role in its In resistance phenotype. The negative impact of In might be related to the high accumulation of the metal into the mutant cells showing In concentration up to approximately 4-fold higher than the native strain. In addition, the expression of the yqaA gene in this mutant reverted the bacterial phenotype with a significant decrease of In accumulation levels into the cells and an increase of In resistance. Membrane potential measurements showed similar values for native and mutant cells, suggesting that there was no loss of proton-motive force in the mutant cells. The results from this study suggest a potential role of this DedA family protein as a membrane transporter involved in the In efflux process. The mutant strain also has the potential to be used as a biotool in bioaccumulation strategies, for the recovery of In in biomining activities.

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