scholarly journals Fission Yeast Rho5p GTPase Is a Functional Paralogue of Rho1p That Plays a Role in Survival of Spores and Stationary-Phase Cells

2006 ◽  
Vol 5 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Sergio A. Rincón ◽  
Beatriz Santos ◽  
Pilar Pérez
Keyword(s):  
Cell Wall ◽  
Stationary Phase ◽  
Fission Yeast ◽  
Rho Gtpase ◽  
Eukaryotic Cell ◽  
Dominant Negative ◽  
Lytic Enzymes ◽  
Morphological Effect ◽  
Actin Organization ◽  
Cell Functions

ABSTRACT The Rho GTPase family and their effectors are key regulators involved in many eukaryotic cell functions related to actin organization and polarity establishment. Schizosaccharomyces pombe Rho1p is essential, directly activates the (1,3)-β-d-glucan synthase, and participates in regulation of cell wall growth and morphogenesis. Here we describe the characterization of the fission yeast Rho5p GTPase, highly homologous to Rho1p, sharing 86% identity and 95% similarity. Overexpression of the hyperactive allele rho5-G15V causes a morphological effect similar to that of rho1-G15V, but the penetrance is significantly lower, and overexpression of the dominant-negative allele rho5-T20N causes lysis like that of rho1-T20N. Importantly, overexpression of rho5 + but no other rho genes is able to rescue the lethality of rho1Δ cells. Shutoff experiments indicated that Rho5p can replace Rho1p, but it is not as effective in maintaining cell wall integrity or actin organization. rho5 + expression is hardly detected during log-phase growth but is induced under nutritional starvation conditions. rho5Δ cells are viable and do not display any defects during logarithmic growth. However, when rho1 + expression is repressed during stationary phase, rho5Δ cells display reduced viability. Ascospores lacking Rho5p are less resistant to heat or lytic enzymes than wild-type spores. Moreover, h90 mutant strains carrying the hyperactive rho5-G15V or the dominant-negative rho5-T20N alleles display severe ascospore formation defects. These results suggest that Rho5p functions in a way similar to, but less efficient than, Rho1p, plays a nonessential role during stationary phase, and participates in the spore wall formation.

scholarly journals Novel Rho GTPase Involved in Cytokinesis and Cell Wall Integrity in the Fission Yeast Schizosaccharomyces pombe

2003 ◽  
Vol 2 (3) ◽  
pp. 521-533 ◽  
Author(s):  
Beatriz Santos ◽  
Javier Gutiérrez ◽  
Teresa M. Calonge ◽  
Pilar Pérez
Keyword(s):  
Cell Wall ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Cell Wall Integrity ◽  
Glucan Synthase ◽  
Actin Organization ◽  
Morphological Defects

ABSTRACT The Rho family of GTPases is present in all eukaryotic cells from yeast to mammals; they are regulators in signaling pathways that control actin organization and morphogenetic processes. In yeast, Rho GTPases are implicated in cell polarity processes and cell wall biosynthesis. It is known that Rho1 and Rho2 are key proteins in the construction of the cell wall, an essential structure that in Schizosaccharomyces pombe is composed of β-glucan, α-glucan, and mannoproteins. Rho1 regulates the synthesis of 1,3-β-d-glucan by activation of the 1,3-β-d-glucan synthase, and Rho2 regulates the synthesis of α-glucan by the 1,3-α-d-glucan synthase Mok1. Here we describe the characterization of another Rho GTPase in fission yeast, Rho4. rho4Δ cells are viable but display cell separation defects at high temperature. In agreement with this observation, Rho4 localizes to the septum. Overexpression of rho4 + causes lysis and morphological defects. Several lines of evidence indicate that both rho4 + deletion or rho4 + overexpression result in a defective cell wall, suggesting an additional role for Rho4 in cell wall integrity. rho4Δ cells also accumulate secretory vesicles around the septum and are defective in actin polarization. We propose that Rho4 could be involved in the regulation of the septum degradation during cytokinesis.

Polarized trafficking of E-cadherin is regulated by Rac1 and Cdc42 in Madin-Darby canine kidney cells

2005 ◽  
Vol 288 (6) ◽  
pp. C1411-C1419 ◽  
Author(s):  
Bo Wang ◽  
Fiona G. Wylie ◽  
Rohan D. Teasdale ◽  
Jennifer L. Stow
Keyword(s):  
Cell Surface ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Dominant Negative ◽  
Adhesion Protein ◽  
Cell Functions ◽  
Golgi Transport ◽  
Polarized Trafficking ◽  
Basolateral Trafficking ◽  
E Cadherin

E-cadherin is a major cell-cell adhesion protein of epithelia that is trafficked to the basolateral cell surface in a polarized fashion. The exact post-Golgi route and regulation of E-cadherin transport have not been fully described. The Rho GTPases Cdc42 and Rac1 have been implicated in many cell functions, including the exocytic trafficking of other proteins in polarized epithelial cells. These Rho family proteins are also associated with the cadherin-catenin complexes at the cell surface. We have used functional mutants of Rac1 and Cdc42 and inactivating toxins to demonstrate specific roles for both Cdc42 and Rac1 in the post-Golgi transport of E-cadherin. Dominant-negative mutants of Cdc42 and Rac1 accumulate E-cadherin at a distinct post-Golgi step. This accumulation occurs before p120 ctn interacts with E-cadherin, because p120 ctn localization was not affected by the Cdc42 or Rac1 mutants. Moreover, the GTPase mutants had no effect on the trafficking of a targeting mutant of E-cadherin, consistent with the selective involvement of Cdc42 and Rac1 in basolateral trafficking. These results provide a new example of Rho GTPase regulation of basolateral trafficking and demonstrate novel roles for Cdc42 and Rac1 in the post-Golgi transport of E-cadherin.

Fission yeast protein kinase C gene homologues are required for protoplast regeneration: a functional link between cell wall formation and cell shape control

1994 ◽  
Vol 107 (5) ◽  
pp. 1131-1136 ◽  
Author(s):  
H. Kobori ◽  
T. Toda ◽  
H. Yaguchi ◽  
M. Toya ◽  
M. Yanagida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fission Yeast ◽  
Wild Type Strain ◽  
Protoplast Regeneration ◽  
Cell Wall Formation ◽  
Wild Type ◽  
Intact Cells ◽  
Actin Organization ◽  
Wall Formation ◽  
Kinase C

Two novel protein kinase C (n PKC) gene homologues, pck1+ and pck2+ were isolated from the fission yeast Schizosaccharomyces pombe (Toda et al. (1993) EMBO J. 12, 1987). We examined the functional differences of pck1+ and pck2+ in cell wall formation and actin organization of S. pombe. Regenerating protoplasts of a wild-type strain, single gene disruptants of pck1+ (delta pck1) and pck2+ (delta pck2) were used as a simple model to examine the functional links between PKC, cell wall formation and actin organization. Protoplasts of the wild-type strain and those of delta pck1 reverted to intact cells in osmotically stabilized liquid medium. A close spatial association between new cell wall formation and actin was observed in these two strains. In delta pck2, protoplasts did not revert to intact cells: (1) scarcely any new cell wall material was formed; (2) actin was not reorganized; and (3) nuclear division and an increase in the amount of cytoplasm were observed in the regenerating protoplasts. These findings demonstrate that the pck2+ gene has a function essential for protoplast regeneration but the pck1+ gene does not. Involvement of n PKCs in cell wall formation and actin organization was also clarified. The effect of staurosporine (a potent inhibitor of protein kinases) on regenerating protoplasts of the three strains confirmed the assumption that the pck2 protein is an in vivo target of staurosporine in the fission yeast.

A Computational Method for the Identification of Endolysins and Autolysins

2020 ◽  
Vol 27 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Lei Xu ◽  
Guangmin Liang ◽  
Baowen Chen ◽  
Xu Tan ◽  
Huaikun Xiang ◽  
...  
Keyword(s):  
Support Vector Machine ◽  
Cell Wall ◽  
Experimental Results ◽  
Computational Method ◽  
Lytic Enzyme ◽  
Support Vector ◽  
Lytic Enzymes ◽  
Data Set ◽  
Optimal Feature ◽  
Better Than

Background: Cell lytic enzyme is a kind of highly evolved protein, which can destroy the cell structure and kill the bacteria. Compared with antibiotics, cell lytic enzyme will not cause serious problem of drug resistance of pathogenic bacteria. Thus, the study of cell wall lytic enzymes aims at finding an efficient way for curing bacteria infectious. Compared with using antibiotics, the problem of drug resistance becomes more serious. Therefore, it is a good choice for curing bacterial infections by using cell lytic enzymes. Cell lytic enzyme includes endolysin and autolysin and the difference between them is the purpose of the break of cell wall. The identification of the type of cell lytic enzymes is meaningful for the study of cell wall enzymes. Objective: In this article, our motivation is to predict the type of cell lytic enzyme. Cell lytic enzyme is helpful for killing bacteria, so it is meaningful for study the type of cell lytic enzyme. However, it is time consuming to detect the type of cell lytic enzyme by experimental methods. Thus, an efficient computational method for the type of cell lytic enzyme prediction is proposed in our work. Method: We propose a computational method for the prediction of endolysin and autolysin. First, a data set containing 27 endolysins and 41 autolysins is built. Then the protein is represented by tripeptides composition. The features are selected with larger confidence degree. At last, the classifier is trained by the labeled vectors based on support vector machine. The learned classifier is used to predict the type of cell lytic enzyme. Results: Following the proposed method, the experimental results show that the overall accuracy can attain 97.06%, when 44 features are selected. Compared with Ding's method, our method improves the overall accuracy by nearly 4.5% ((97.06-92.9)/92.9%). The performance of our proposed method is stable, when the selected feature number is from 40 to 70. The overall accuracy of tripeptides optimal feature set is 94.12%, and the overall accuracy of Chou's amphiphilic PseAAC method is 76.2%. The experimental results also demonstrate that the overall accuracy is improved by nearly 18% when using the tripeptides optimal feature set. Conclusion: The paper proposed an efficient method for identifying endolysin and autolysin. In this paper, support vector machine is used to predict the type of cell lytic enzyme. The experimental results show that the overall accuracy of the proposed method is 94.12%, which is better than some existing methods. In conclusion, the selected 44 features can improve the overall accuracy for identification of the type of cell lytic enzyme. Support vector machine performs better than other classifiers when using the selected feature set on the benchmark data set.

scholarly journals Cell wall and organelle modifications during nitrogen starvation in Nannochloropsis oceanica F&M-M24

2021 ◽  
Author(s):  
Roncaglia Bianca ◽  
Papini Alessio ◽  
Chini Zittelli Graziella ◽  
Rodolfi Liliana ◽  
Mario R. Tredici
Keyword(s):  
Cell Wall ◽  
Wall Thickness ◽  
Lipid Droplets ◽  
Nitrogen Starvation ◽  
Photosynthetic Apparatus ◽  
Ultrastructural Changes ◽  
Total Biomass ◽  
Nannochloropsis Oceanica ◽  
Final Phase ◽  
Cell Functions

AbstractNannochloropsis oceanica F&M-M24 is able to increase its lipid content during nitrogen starvation to more than 50% of the total biomass. We investigated the ultrastructural changes and the variation in the content of main cell biomolecules that accompany the final phase of lipid accumulation. Nitrogen starvation induced a first phase of thylakoid disruption followed by chloroplast macroautophagy and formation of lipid droplets. During this phase, the total amount of proteins decreased by one-third, while carbohydrates decreased by 12–13%, suggesting that lipid droplets were formed by remodelling of chloroplast membranes and synthesis of fatty acids from carbohydrates and amino acids. The change in mitochondrial ultrastructure suggests also that these organelles were involved in the process. The cell wall increased its thickness and changed its structure during starvation, indicating that a disruption process could be partially affected by the increase in wall thickness for biomolecules recovery from starved cells. The wall thickness in strain F&M-M24 was much lower than that observed in other strains of N. oceanica, showing a possible advantage of this strain for the purpose of biomolecules extraction. The modifications following starvation were interpreted as a response to reduction of availability of a key nutrient (nitrogen). The result is a prolonged survival in quiescence until an improvement of the environmental conditions (nutrient availability) allows the rebuilding of the photosynthetic apparatus and the full recovery of cell functions.

scholarly journals PAK and other Rho-associated kinases – effectors with surprisingly diverse mechanisms of regulation

2005 ◽  
Vol 386 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Zhou-shen ZHAO ◽  
Ed MANSER
Keyword(s):  
Rho Gtpases ◽  
Cell Biology ◽  
Rho Gtpase ◽  
Rho Kinase ◽  
Molecular Switches ◽  
Eukaryotic Cell ◽  
Effector Proteins ◽  
Downstream Effector ◽  
P21 Activated Kinase ◽  
Do So

The Rho GTPases are a family of molecular switches that are critical regulators of signal transduction pathways in eukaryotic cells. They are known principally for their role in regulating the cytoskeleton, and do so by recruiting a variety of downstream effector proteins. Kinases form an important class of Rho effector, and part of the biological complexity brought about by switching on a single GTPase results from downstream phosphorylation cascades. Here we focus on our current understanding of the way in which different Rho-associated serine/threonine kinases, denoted PAK (p21-activated kinase), MLK (mixed-lineage kinase), ROK (Rho-kinase), MRCK (myotonin-related Cdc42-binding kinase), CRIK (citron kinase) and PKN (protein kinase novel), interact with and are regulated by their partner GTPases. All of these kinases have in common an ability to dimerize, and in most cases interact with a variety of other proteins that are important for their function. A diversity of known structures underpin the Rho GTPase–kinase interaction, but only in the case of PAK do we have a good molecular understanding of kinase regulation. The ability of Rho GTPases to co-ordinate spatial and temporal phosphorylation events explains in part their prominent role in eukaryotic cell biology.

Searching for the Evolutionary Design of the Pneumococcal Cell Wall Lytic Enzymes

1993 ◽  
pp. 253-259
Author(s):  
Rubens López ◽  
José L. García ◽  
Eduardo Díaz ◽  
Jesús M. Sanz ◽  
José M. Sánchez-Puelles ◽  
...  
Keyword(s):  
Cell Wall ◽  
Evolutionary Design ◽  
Lytic Enzymes ◽  
Cell Wall Lytic Enzymes
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