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Abstract Detail

Cell Biology/Physiology

Corrales-Vargas, Isabel [1], Cano-Domínguez, Nallely [1], Amarillas-González, Marisol [1], Castro-Longoria, Ernestina [1].

Phenotypic characterization of the RhoGAPs mutants Δbem-3, Δrgd-1 and Δrga-1 in Neurospora crassa.

In eukaryotic organisms, the Rho GTPases are known to function as molecular switches that regulate diverse biological processes such as cell polarization through the organization of actin cytoskeleton. In yeasts Cdc42 has been extensively studied, but in filamentous fungi Rac has been reported as a second Rho GTPase involved in cell polarity establishment.  In Neurospora crassa CDC-42 and RAC are important components that regulate cell polarity establishment displaying distinct functions at the hyphal tip. Therefore, in order to understand the spatial and temporal regulation of the Rho GTPases, it is critical to investigate the role of the positive regulators (Guanine Exchange Factor or “GEFs”) and the negative regulators (GTPase-activating Proteins or “GAPs”) that control the active-GTP and inactive-GDP state of those switches in fungal morphogenesis. The genome of N. crassa contains seven putative RhoGEFs and ten putative RhoGAPs to regulate six Rho GTPases (RHO1-4, CDC-42 and RAC). The only regulators reported in this fungus are one RhoGEF (CDC-24) and one RhoGAP (LGR-1) and currently, there are not available studies of any negative regulators of CDC-42 and RAC. In this work, we characterized the phenotype of null mutants of three putative RhoGAPs BEM-3 (∆bem-3), RGD-1 (∆rgd-1) and RGA-1 (∆rga-1) and compared them with the wild type strain. The ∆rgd-1 strain showed a slightly higher elongation rate, while the rest of simple null mutants did not display significant differences in colonial extension rate. All the simple deletion mutants showed reduced production of conidia and hyphae with higher number of branches. Also the sexual cell cycle seems to be affected since the strains ∆bem-3, Δrga-1 and the double mutant Δrgd-1;Δbem-3 presented a delayed protoperithecia formation and the Δrga-1 is not able of produce mature perithecia and asci. To fully explore the role of the RhoGAPs in fungal morphogenesis, we are working on the construction of transformant strains expressing the RhoGAPs labeled with GFP to analyze their dynamics and distribution in different developmental stages in N. crassa.

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1 - CICESE, Microbiology, 3918 Carretera Ensenada-Tijuana, Zona Playitas , Ensenada, Baja California, 22860, Mexico

Cell Polarity
N. crassa.

Presentation Type: Offered Paper - Paper
Session: 6
Location: Room 104 AB/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 2:00 PM
Number: 6005
Abstract ID:189
Candidate for Awards:None

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