Role of Cfh3p in the morphogenesis of Schizosaccharomyces pombe

[ES]El objetivo del presente trabajo fue estudiar el papel de Cfh3p en la celda síntesis de la pared y en la morfogénesis en Schizosaccharomyces pombe.[EN]The objective of the present work was to study the role of Cfh3p in cell wall synthesis and in morphogenesis in Schizosaccharomyces pombe

The Schizosaccharomyces pombe Map4 adhesin is a glycoprotein that can be extracted from the cell wall with alkali but not with β-glucanases and requires the C-terminal DIPSY domain for function

El pdf del artículo es la versión pre-print.In fungi, cell adhesion is required for flocculation, mating and virulence, and it is mediated by covalently bound cell wall proteins termed adhesins. Map4, an adhesin required for mating in Schizosaccharomyces pombe, is N-glycosylated and O-glycosylated, and is an endogenous substrate for the mannosyl transferase Oma4p. Map4 has a modular structure with an N-terminal signal peptide, a serine and threonine (S/T)-rich domain that includes nine repeats of 36 amino acids (rich in serine and threonine residues, but lacking glutamines), and a C-terminal DIPSY domain with no glycosylphosphatidyl inositol (GPI)-anchor signal. Map4 can be extracted from cell walls with SDS/mercaptoethanol sample buffer or with mild alkali solutions. After extensive extraction with hot sample buffer, no more protein can be released by β-glucanases or alkali. Additionally, none of the cysteine residues of the protein is required for its retention at the cell wall. These results show that Map4 is not directly bound to β-glucans and point to the existence of alkali- and SDS/mercaptoethanol-sensitive linkages between cell wall proteins. The N-terminal S/T-rich regions are required for cell wall attachment, but the C-terminal DIPSY domain is required for agglutination and mating in liquid and solid media. © 2008 The Authors.This work has been supported by Grant BFU2007-61866 from the CICYT and Grant SA104A/07 from the Junta de Castilla y León, Spain. M.R.S. is supported by a fellowship from the Government of Iran.Peer Reviewe

The role for the exocyst complex subunits Exo70B2 and Exo70H1 in the plant–pathogen interaction

Recently, the octameric vesicle-tethering complex exocyst was found in plants and its importance for Arabidopsis morphogenesis was demonstrated. Exo70 exocyst subunits in plants, unlike in yeasts and mammals, are represented by a multigene family, comprising 23 members in Arabidopsis. For Exo70B2 and Exo70H1 paralogues, transcriptional up-regulation was confirmed on treatment with an elicitor peptide, elf18, derived from the bacterial elongation factor. Their ability to participate in the exocyst complex formation was inferred by the interaction of both the Exo70s with several other exocyst subunits using the yeast two-hybrid system. Arabidopsis plants mutated in these two genes were used to analyse their local reaction upon inoculation with Pseudomonas syringae pv. maculicola and the fungal pathogen Blumeria graminis f. sp. hordei. The Pseudomonas sensitivity test revealed enhanced susceptibility for the two exo70B2 and one H1 mutant lines. After Blumeria inoculation, an increase in the proportion of abnormal papilla formation, with an unusual wide halo made of vesicle-like structures, was found in exo70B2 mutants. Intracellular localization of both Exo70 proteins was studied following a GFP fusion assay and Agrobacterium-mediated transient expression of the constructs in Nicotiana benthamiana leaf epidermis. GFP-Exo70H1 localizes in the vesicle-like structures, while GFP-Exo70B2 is localized mainly in the cytoplasm. It is concluded that both Exo70B2 and Exo70H1 are involved in the response to pathogens, with Exo70B2 having a more important role in cell wall apposition formation related to plant defence

Different steps of sexual development are differentially regulated by the Sec8p and Exo70p exocyst subunits

10 páginas, 5 figuras.-- El pdf del artículo es la versión pre-print.In this paper we show that in Schizosaccharomyces pombe, mating-specific cell adhesion is dependent on the exocyst subunit Sec8p, but independent of the exocyst subunit Exo70p. In the absence of Exo70p, the forespore membrane does not develop properly and the leading edge protein Meu14p is abnormally distributed. Additionally, the spindle pole body is aberrant in a significant number of exo70Δ asci. In both the sec8-1 and the exo70Δ mutants, the development of the spore cell wall is impaired. These results show that different steps of sexual development are differentially regulated by the exocyst and suggest the existence of exocyst subcomplexes with distinct roles in mating.This work has been supported by grants BFU2007-61866 from the CICYTand GR231 from the Junta de Castilla y León, Spain. M.R.S. and N.d.L. were supported by fellowships from the Iranian and Spanish Ministry of Science, respectively.Peer reviewe

The Effect of Plant Growth Regulators on Callus Induction and Regeneration of Amygdalus communis

The Almond (Amygdalus communis) is one of the most important and oldest commercial nut crops, belonging to the Rosaceae family. Almond has been used as base material in pharmaceutical, cosmetic, hygienically and food industry. Propagation by tissue culture technique is the most important one in woody plants. In the current research, in vitro optimization of tissue culture and mass production of almond was investigated. In this idea, explants of actively growing shoots were collected and sterilized, then transferred to MS medium with different concentrations and combinations of plant growth regulators. The experiment was done in completely randomized blocks design, with 7 treatment and 30 replications. After 4 weeks, calli induction, proliferation, shoot length and number of shoot per explants were measured. Results showed that the best medium for shoot initiation and proliferation was MS + 0.5 mg/l IAA (Indol-3-Acetic Acid) + 1 mg/l BA (Benzyl Adenine). Autumn was the best season for collecting explants. The shoots were transferred to root induction medium with different concentrations of plant growth regulators. The best root induction medium was MS + 0.5 mg/l IBA (Indol Butyric Acid)

Regulation of cell wall synthesis by the clathrin light chain is essential for viability in Schizosaccharomyces pombe

This is an open-access article distributed under the terms of the Creative Commons Attribution License.The regulation of cell wall synthesis by the clathrin light chain has been addressed. Schizosaccharomyces pombe clc1Δ mutant was inviable in the absence of osmotic stabilization; when grown in sorbitol-supplemented medium clc1Δ cells grew slowly, formed aggregates, and had strong defects in morphology. Additionally, clc1Δ cells exhibited an altered cell wall composition. A mutant that allowed modulating the amount of Clc1p was created to analyze in more detail the dependence of cell wall synthesis on clathrin. A 40% reduction in the amount of Clc1p did not affect acid phosphatase secretion and bulk lipid internalization. Under these conditions, β(1,3)glucan synthase activity and cell wall synthesis were reduced. Also, the delivery of glucan synthases to the cell surface, and the secretion of the Eng1p glucanase were defective. These results suggest that the defects in the cell wall observed in the conditional mutant were due to a defective secretion of enzymes involved in the synthesis/remodelling of this structure, rather than to their endocytosis. Our results show that a reduction in the amount of clathrin that has minor effects on general vesicle trafficking has a strong impact on cell wall synthesis, and suggest that this is the reason for the lethality of clc1Δ cells in the absence of osmotic stabilization.Financial support to our group from the MICINN (http://www.idi.mineco.gob.es/. Spain)/European Union FEDER program (grant BFU2010-15085) made this work possible. NdL and MAC were supported by FPU fellowships from the Ministry of Science, and MH was supported by a JAE-PREDOC fellowship from Consejo Superior de Investigaciones Cientificas, Spain.Peer Reviewe

Estudio de la relación funcional entre las proteínas tetraspán Dni1p, Dni2p y Prm1p en el proceso de conjugación de Schizosaccharomyces pombe

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The integrity of the cytokinesis machinery under stress conditions requires the Glucan synthase Bgs1p and its regulator Cfh3p

This is an open-access article distributed under the terms of the Creative Commons Attribution License.In yeast, cytokinesis requires coordination between nuclear division, acto-myosin ring contraction, and septum synthesis. We studied the role of the Schizosaccharomyces pombe Bgs1p and Cfh3p proteins during cytokinesis under stress conditions. Cfh3p formed a ring in the septal area that contracted during mitosis; Cfh3p colocalized and co-immunoprecipitated with Cdc15p, showing that Cfh3p interacted with the contractile acto-myosin ring. In a wild-type strain, a significant number of contractile rings collapsed under stress conditions and this number increased dramatically in the cfh3Δ, bgs1cps1-191, and cfh3Δ bgs1/cps1-191. Our results show that after osmotic shock Cfh3p is essential for the stability of the (1,3) glucan synthase Bgs1p in the septal area, but not at the cell poles. Finally, cells adapted to stress; they repaired their contractile rings and re-localized Bgs1p to the cell surface some time after osmotic shock. A detailed analysis of the cytokinesis machinery in the presence of KCl revealed that the actomyosin ring collapsed before Bgs1p was internalized, and that it was repaired before Bgs1p re-localized to the cell surface. In the cfh3Δ, bgs1/cps1-191, and cfh3Δ bgs1/cps1-191 mutants, which have reduced glucan synthesis, the damage produced to the ring had stronger consequences, suggesting that an intact primary septum contributes to ring stability. The results show that the contractile actomyosin ring is very sensitive to stress, and that cells have efficient mechanisms to remedy the damage produced in this structure. © 2012 Sharifmoghadam et al.Financial support to the Instituto de Biología Funcional y Genómica (IBFG) from the Fundación Ramón Areces and to our group from the Comisión Interministerial de Ciencia y Tecnología (CICYT) (Spain)/European Union FEDER (Fondo Europeo de Desarrollo Regional) program (grant BFU2007-61866) made this work possible. Dr. Curto was supported by a contract for training in research and technological innovation by Junta de Castilla y León and by Formación de Personal Investigador (FPU) fellowship. Dr. de León and Dr. Hoya were supported by FPU and Junta de Ampliación de Estudios (JAE)-PREDOC fellowships from the Ministry of Science and Consejo Superior de Investigaciones Científicas (CSIC), Spain, respectively.Peer Reviewe

The fission yeast Map4 protein is a novel adhesin required for mating

AbstractCell adhesion is required for many cellular processes. In fungi, cell–cell contact during mating, flocculation or virulence is mediated by adhesins, which typically are glycosyl phosphatidyl inositol (GPI)-modified cell wall glycoproteins. Proteins with internal repeats (PIR) are surface proteins involved in the response to stress. In Schizosaccharomyces pombe no adhesins or PIR proteins have been described. Here we study the S. pombe Map4p, which defines a new class of surface protein that is not GPI-modified and has a serine/threonine rich domain and internal repeats that differ from those present in PIR proteins. Map4p is a mating type-specific adhesin required for mating in h+ cells and enhances cell adhesion when overexpressed