scholarly journals Characterization of Dip1p Reveals a Switch in Arp2/3-Dependent Actin Assembly for Fission Yeast Endocytosis

2011 ◽  
Vol 21 (11) ◽  
pp. 905-916 ◽  
Author(s):  
Roshni Basu ◽  
Fred Chang
Keyword(s):  
2011 ◽  
Vol 22 (20) ◽  
pp. 3826-3839 ◽  
Author(s):  
Bonnie J. Scott ◽  
Erin M. Neidt ◽  
David R. Kovar

Fission yeast expresses three formins required for distinct actin cytoskeletal processes: Cdc12 (cytokinesis), For3 (polarization), and Fus1 (mating). We propose that in addition to differential regulation, key actin-assembly properties tailor formins for a particular role. In direct comparison to the well-studied Cdc12, we report the first in vitro characterization of the actin-assembly properties of For3 and Fus1. All three share fundamental formin activities; however, particular reaction rates vary significantly. Cdc12 is an efficient nucleator (one filament per approximately 3 Cdc12 dimers) that processively elongates profilin-actin at a moderate rate of 10 subunits s−1 μM−1, but lacks filament-bundling activity. Fus1 is also an efficient nucleator, yet processively elongates profilin-actin at one-half the rate of and dissociates 10-fold more rapidly than Cdc12; it also bundles filaments. For3 nucleates filaments 100-fold less well than Fus1, but like Cdc12, processively elongates profilin-actin at a moderate rate and lacks filament-bundling activity. Additionally, both the formin homology FH1 and FH2 domains contribute to the overall rate of profilin-actin elongation. We also confirmed the physiological importance of the actin-assembly activity of the fission yeast formins. Point mutants that disrupt their ability to stimulate actin assembly in vitro do not function properly in vivo.


2013 ◽  
Vol 41 (10) ◽  
pp. 5382-5399 ◽  
Author(s):  
Mayumi Sasaki ◽  
Hiromichi Kumagai ◽  
Kaoru Takegawa ◽  
Hideki Tohda
Keyword(s):  

2016 ◽  
Vol 27 (16) ◽  
pp. 2528-2541 ◽  
Author(s):  
Yajun Liu ◽  
I-Ju Lee ◽  
Mingzhai Sun ◽  
Casey A. Lower ◽  
Kurt W. Runge ◽  
...  

Rho GAPs are important regulators of Rho GTPases, which are involved in various steps of cytokinesis and other processes. However, regulation of Rho-GAP cellular localization and function is not fully understood. Here we report the characterization of a novel coiled-coil protein Rng10 and its relationship with the Rho-GAP Rga7 in fission yeast. Both rng10Δ and rga7Δ result in defective septum and cell lysis during cytokinesis. Rng10 and Rga7 colocalize on the plasma membrane at the cell tips during interphase and at the division site during cell division. Rng10 physically interacts with Rga7 in affinity purification and coimmunoprecipitation. Of interest, Rga7 localization is nearly abolished without Rng10. Moreover, Rng10 and Rga7 work together to regulate the accumulation and dynamics of glucan synthases for successful septum formation in cytokinesis. Our results show that cellular localization and function of the Rho-GAP Rga7 are regulated by a novel protein, Rng10, during cytokinesis in fission yeast.


2018 ◽  
Author(s):  
Valerie Wood ◽  
Antonia Lock ◽  
Midori A. Harris ◽  
Kim Rutherford ◽  
Jürg Bähler ◽  
...  

AbstractThe first decade of genome sequencing stimulated an explosion in the characterization of unknown proteins. More recently, the pace of functional discovery has slowed, leaving around 20% of the proteins even in well-studied model organisms without informative descriptions of their biological roles. Remarkably, many uncharacterized proteins are conserved from yeasts to human, suggesting that they contribute to fundamental biological processes. To fully understand biological systems in health and disease, we need to account for every part of the system. Unstudied proteins thus represent a collective blind spot that limits the progress of both basic and applied biosciences.We use a simple yet powerful metric based on Gene Ontology (GO) biological process terms to define characterized and uncharacterized proteins for human, budding yeast, and fission yeast. We then identify a set of conserved but unstudied proteins in S. pombe, and classify them based on a combination of orthogonal attributes determined by large-scale experimental and comparative methods. Finally, we explore possible reasons why these proteins remain neglected, and propose courses of action to raise their profile and thereby reap the benefits of completing the catalog of proteins’ biological roles.


1994 ◽  
Vol 14 (6) ◽  
pp. 3895-3905
Author(s):  
S Kjaerulff ◽  
J Davey ◽  
O Nielsen

We previously identified two genes, mfm1 and mfm2, with the potential to encode the M-factor mating pheromone of the fission yeast Schizosaccharomyces pombe (J. Davey, EMBO J. 11:951-960, 1992), but further analysis revealed that a mutant strain lacking both genes still produced active M-factor. Here we describe the isolation and characterization of a third M-factor gene, mfm3. A mutant lacking all three genes fails to produce M-factor, indicating that all functional M-factor genes now have been identified. The triple mutant exhibits an absolute mating defect in M cells, a defect that is not rescued by addition of exogenous M-factor. A mutational analysis reveals that all three mfm genes contribute to the production of M-factor. Their transcription is limited to M cells and requires the mat1-Mc and ste11 gene products. Each gene is induced when the cells are starved of nitrogen and further induced by a pheromone signal. Additionally, the signal transduction machinery associated with the pheromone response is required for transcription of the mfm genes in both stimulated and unstimulated cells.


2004 ◽  
Vol 15 (5) ◽  
pp. 2287-2301 ◽  
Author(s):  
Srinivas Venkatram ◽  
Joseph J. Tasto ◽  
Anna Feoktistova ◽  
Jennifer L. Jennings ◽  
Andrew J. Link ◽  
...  

The γ-tubulin complex, via its ability to organize microtubules, is critical for accurate chromosome segregation and cytokinesis in the fission yeast, Schizosaccharomyces pombe. To better understand its roles, we have purified the S. pombe γ-tubulin complex. Mass spectrometric analyses of the purified complex revealed known components and identified two novel proteins (i.e., Mbo1p and Gfh1p) with homology to γ-tubulin–associated proteins from other organisms. We show that both Mbo1p and Gfh1p localize to microtubule organizing centers. Although cells deleted for either mbo1+ or gfh1+ are viable, they exhibit a number of defects associated with altered microtubule function such as defects in cell polarity, nuclear positioning, spindle orientation, and cleavage site specification. In addition, mbo1Δ and gfh1Δ cells exhibit defects in astral microtubule formation and anchoring, suggesting that these proteins have specific roles in astral microtubule function. This study expands the known roles of γ-tubulin complex components in organizing different types of microtubule structures in S. pombe.


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