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Fission yeast

Navin Gopaldass, Bruno Fauvet, Hilal Lashuel, Aurélien Roux, Andreas Mayer
Sorting, transport, and autophagic degradation of proteins in endosomes and lysosomes, as well as the division of these organelles, depend on scission of membrane-bound tubulo-vesicular carriers. How scission occurs is poorly understood, but family proteins bind these membranes. Here, we show that the yeast PROPPIN Atg18 carries membrane scission activity. Purified Atg18 drives tubulation and scission of giant unilamellar vesicles. Upon membrane contact, Atg18 folds its unstructured CD loop into an amphipathic α-helix that inserts into the bilayer...
October 13, 2017: EMBO Journal
Bayram Cucu, Daniel Degreif, Adam Bertl, Gerhard Thiel
Measurements of the membrane capacitance on animal cells has provided an excellent technique for monitoring of exo- and endocytotic activity in intact living cells. Here we review recent data in which the same technique was applied to plant cells and cells of the budding yeast Saccharomyces cerevisiae. The data show that unitary exo- and endocytotic events can also be measured with the same technique after removing the cell wall from these cells. The resulting protoplasts execute the same type of transient and permanent fusion/fission that is known from animal cells...
November 2017: Cell Calcium
Masashi Yukawa, Tomoki Kawakami, Masaki Okazaki, Kazunori Kume, Ngang Heok Tang, Takashi Toda
Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end directed motor Kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end directed motor Kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of Kinesin-5/Cut7 and Kinesin-14/Pkl1...
October 11, 2017: Molecular Biology of the Cell
Sophie Tessé, Henri-Marc Bourbon, Robert Debuchy, Karine Budin, Emeline Dubois, Zhang Liangran, Romain Antoine, Tristan Piolot, Nancy Kleckner, Denise Zickler, Eric Espagne
Meiosis is the cellular program by which a diploid cell gives rise to haploid gametes for sexual reproduction. Meiotic progression depends on tight physical and functional coupling of recombination steps at the DNA level with specific organizational features of meiotic-prophase chromosomes. The present study reveals that every step of this coupling is mediated by a single molecule: Asy2/Mer2. We show that Mer2, identified so far only in budding and fission yeasts, is in fact evolutionarily conserved from fungi (Mer2/Rec15/Asy2/Bad42) to plants (PRD3/PAIR1) and mammals (IHO1)...
October 11, 2017: Genes & Development
Manuel Alonso Y Adell, Simona M Migliano, Srigokul Upadhyayula, Yury S Bykov, Simon Sprenger, Mehrshad Pakdel, Georg F Vogel, Gloria Jih, Wesley Skillern, Reza Behrouzi, Markus Babst, Oliver Schmidt, Michael W Hess, John Ag Briggs, Tomas Kirchhausen, David Teis
The ESCRT machinery mediates reverse membrane scission. By quantitative fluorescence lattice light-sheet microscopy, we have shown that ESCRT-III subunits polymerize rapidly on yeast endosomes, together with the recruitment of at least two Vps4 hexamers. During their 3-45 second lifetimes, the ESCRT-III assemblies accumulated 75-200 Snf7 and 15-50 Vps24 molecules. Productive budding events required at least two additional Vps4 hexamers. Membrane budding was associated with continuous, stochastic exchange of Vps4 and ESCRT-III components, rather than steady growth of fixed assemblies, and depended on Vps4 ATPase activity...
October 11, 2017: ELife
Kurt W Runge, Yanhui Li
Chromosomal breaks can be healed by several repair processes, including one called non-homologous end-joining (NHEJ) where the two broken ends are ligated together with a loss of 0-5 bp of DNA. The protein requirements for NHEJ of cut DNA ends in the budding yeast Saccharomyces cerevisiae include its version of the Mre11-Rad50-Nbs1 (MRN) complex. In contrast, the fission yeast Schizosaccharomyces pombe and mammalian cells do not require MRN for this process. Recent work in S. pombe used transposon excision to generate breaks that were capped by DNA hairpins, which must be opened to produce ligatable ends...
October 10, 2017: Current Genetics
Dimitrios Vavylonis, Brandon G Horan
Formins polymerize actin filaments for the cytokinetic contractile ring. Using in vitro reconstitution of fission yeast contractile ring precursor nodes containing formins and myosin, a new study shows that formin-mediated polymerization is strongly inhibited upon the capture and pulling of actin filaments by myosin, a result that has broad implications for cellular mechanosensing.
October 9, 2017: Current Biology: CB
Hideki Tanizawa, Kyoung-Dong Kim, Osamu Iwasaki, Ken-Ichi Noma
Eukaryotic genomes are highly ordered through various mechanisms, including topologically associating domain (TAD) organization. We employed an in situ Hi-C approach to follow the 3D organization of the fission yeast genome during the cell cycle. We demonstrate that during mitosis, large domains of 300 kb-1 Mb are formed by condensin. This mitotic domain organization does not suddenly dissolve, but gradually diminishes until the next mitosis. By contrast, small domains of 30-40 kb that are formed by cohesin are relatively stable across the cell cycle...
October 9, 2017: Nature Structural & Molecular Biology
Thomas Caspari, James Dyer, Nathalie Fenner, Christian Dunn, Chris Freeman
Chlorination of drinking water protects humans from water-born pathogens, but it also produces low concentrations of dibromoacetonitrile (DBAN), a common disinfectant by-product found in many water supply systems. DBAN is not mutagenic but causes DNA breaks and elevates sister chromatid exchange in mammalian cells. The WHO issued guidelines for DBAN after it was linked with cancer of the liver and stomach in rodents. How this haloacetonitrile promotes malignant cell transformation is unknown. Using fission yeast as a model, we report here that DBAN delays G1-S transition...
October 6, 2017: Scientific Reports
Yoshie Sasaki, Ayumi Kojima, Yuriko Shibata, Hiroshi Mitsuzawa
The fission yeast Schizosaccharomyces pombe undergoes a switch from yeast to filamentous invasive growth in response to certain environmental stimuli. Among them is ammonium limitation. Amt1, one of the three ammonium transporters in this yeast, is required for the ammonium limitation-induced morphological transition; however, the underlying molecular mechanism remains to be understood. Cells lacking Amt1 became capable of invasive growth upon increasing concentrations of ammonium in the medium, suggesting that the ammonium taken up into the cell or a metabolic intermediate in ammonium assimilation might serve as a signal for the ammonium limitation-induced morphological transition...
2017: PloS One
Sanki Tashiro, Yuki Nishihara, Kazuto Kugou, Kunihiro Ohta, Junko Kanoh
The subtelomere, a telomere-adjacent chromosomal domain, contains species-specific homologous DNA sequences, in addition to various genes. However, the functions of subtelomeres, particularly subtelomeric homologous (SH) sequences, remain elusive. Here, we report the first comprehensive analyses of the cellular functions of SH sequences in the fission yeast, Schizosaccharomyces pombe. Complete removal of SH sequences from the genome revealed that they are dispensable for mitosis, meiosis and telomere length control...
September 14, 2017: Nucleic Acids Research
Faria Zafar, Akiko K Okita, Atsushi T Onaka, Jie Su, Yasuhiro Katahira, Jun-Ichi Nakayama, Tatsuro S Takahashi, Hisao Masukata, Takuro Nakagawa
Centromeres that are essential for faithful segregation of chromosomes consist of unique DNA repeats in many eukaryotes. Although recombination is under-represented around centromeres during meiosis, little is known about recombination between centromere repeats in mitotic cells. Here, we compared spontaneous recombination that occurs between ade6B/ade6X inverted repeats integrated at centromere 1 (cen1) or at a non-centromeric ura4 locus in fission yeast. Remarkably, distinct mechanisms of homologous recombination (HR) were observed in centromere and non-centromere regions...
August 29, 2017: Nucleic Acids Research
Tamiza Nanji, Xu Liu, Leon H Chew, Franco K Li, Maitree Biswas, Zhong-Qiu Yu, Shan Lu, Meng-Qiu Dong, Li-Lin Du, Daniel J Klionsky, Calvin K Yip
Although the human ULK complex mediates phagophore initiation similar to the budding yeast Saccharomyces cerevisiae Atg1 complex, this complex contains ATG101 but not Atg29 and Atg31. Here, we analyzed the fission yeast Schizosaccharomyces pombe Atg1 complex, which has a subunit composition that resembles the human ULK complex. Our pairwise coprecipitation experiments showed that while the interactions between Atg1, Atg13, and Atg17 are conserved, Atg101 does not bind Atg17. Instead, Atg101 interacts with the HORMA domain of Atg13 and this enhances the stability of both proteins...
October 4, 2017: Autophagy
Silvia Salas-Pino, Paola Gallardo, Ramón R Barrales, Sigurd Braun, Rafael R Daga
Kinetochores (KTs) are large multiprotein complexes that constitute the interface between centromeric chromatin and the mitotic spindle during chromosome segregation. In spite of their essential role, little is known about how centromeres and KTs are assembled and how their precise stoichiometry is regulated. In this study, we show that the nuclear pore basket component Alm1 is required to maintain both the proteasome and its anchor, Cut8, at the nuclear envelope, which in turn regulates proteostasis of certain inner KT components...
October 3, 2017: Journal of Cell Biology
Fabrizio Benedetti, Dusan Racko, Julien Dorier, Yannis Burnier, Andrzej Stasiak
The question of how self-interacting chromatin domains in interphase chromosomes are structured and generated dominates current discussions on eukaryotic chromosomes. Numerical simulations using standard polymer models have been helpful in testing the validity of various models of chromosome organization. Experimental contact maps can be compared with simulated contact maps and thus verify how good is the model. With increasing resolution of experimental contact maps, it became apparent though that active processes need to be introduced into models to recapitulate the experimental data...
September 29, 2017: Nucleic Acids Research
Sathish Thiyagarajan, Shuyuan Wang, Ben O'Shaughnessy
During cytokinesis a contractile actomyosin ring constricts and divides the cell into two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a super-resolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure...
September 27, 2017: Molecular Biology of the Cell
Dennis Zimmermann, Kaitlin E Homa, Glen M Hocky, Luther W Pollard, Enrique M De La Cruz, Gregory A Voth, Kathleen M Trybus, David R Kovar
Cytokinesis physically separates dividing cells by forming a contractile actomyosin ring. The fission yeast contractile ring has been proposed to assemble by Search-Capture-Pull-Release from cytokinesis precursor nodes that include the molecular motor type-II myosin Myo2 and the actin assembly factor formin Cdc12. By successfully reconstituting Search-Capture-Pull in vitro, we discovered that formin Cdc12 is a mechanosensor, whereby myosin pulling on formin-bound actin filaments inhibits Cdc12-mediated actin assembly...
September 26, 2017: Nature Communications
Qi Yan, David Machalz, Andy Zöllner, Erik J Sorensen, Gerhard Wolber, Matthias Bureik
We have established a protocol for the preparation of permeabilized fission yeast cells (enzyme bags) that recombinantly express human cytochrome P450 enzymes (CYPs). A direct comparison of CYP3A4 activity gave an eightfold higher space-time yield for enzyme bag-catalyzed biotransformation as compared to whole-cell biotransformation, even though the total number of cells employed was lower by a factor of 150. Biotransformation of the luminogenic substrate Luciferin-H using CYP2C9-containing enzyme bags proceeded efficiently and stably for 24h...
September 23, 2017: Biochemical Pharmacology
Poonam Thakran, Prashant Arun Pandit, Sumanjit Datta, Kiran Kumar Kolathur, Jeffrey A Pleiss, Shravan Kumar Mishra
The expression of intron-containing genes in eukaryotes requires generation of protein-coding messenger RNAs (mRNAs) via RNA splicing, whereby the spliceosome removes non-coding introns from pre-mRNAs and joins exons. Spliceosomes must ensure accurate removal of highly diverse introns. We show that Sde2 is a ubiquitin-fold-containing splicing regulator that supports splicing of selected pre-mRNAs in an intron-specific manner in Schizosaccharomyces pombe Both fission yeast and human Sde2 are translated as inactive precursor proteins harbouring the ubiquitin-fold domain linked through an invariant GGKGG motif to a C-terminal domain (referred to as Sde2-C)...
September 25, 2017: EMBO Journal
Addison Rains, Yorisha Bryant, Kaitlyn A Dorsett, Austin Culver, Jamal Egbaria, Austin Williams, Matt Barnes, Raeann Lamere, Austin R Rossi, Stephanie C Waldrep, Caroline Wilder, Elliot Kliossis, Melanie L Styers
The yeast vacuole plays key roles in cellular stress responses. Here, we show that deletion of lvs1, the fission yeast homolog of the Chediak-Higashi Syndrome CHS1/LYST gene, increases vacuolar size, similar to deletion of the Rab4 homolog ypt4. Overexpression of lvs1-YFP rescued vacuolar size in ypt4Δ cells, but ypt4-YFP did not rescue lvs1Δ, suggesting that lvs1 may act downstream of ypt4. Vacuoles were capable of hypotonic shock-induced fusion and recovery in both ypt4Δ and lvs1Δ cells, although recovery may be slightly delayed in ypt4Δ...
2017: Cellular Logistics
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