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Abstract Detail

Evolution of Hyphal Function and Development

Castro-Longoria, Ernestina [1].

The architecture and function of cell polarity components in filamentous fungi.

Filamentous fungi are characterized by a highly polarized growth in which the coordinated assembling of multiple protein complexes is required to ensure the establishment and maintenance of cell polarity. In Neurospora crassa the tip growth apparatus of vegetative hyphae has not been fully described. In this work the subcellular organization and dynamics of two important components involved in the establishment, maintenance and termination of polarized cell growth are described: The CDC-42 GTPase module and the polarisome. The CDC-42–RAC–CDC-24 module has a vital role in cell polarity regulation in which the GEF CDC-24 is an essential regulator for RAC and CDC-42. In vivo confocal microscopy shows that this module is organized strategically as a membrane-associated cap that covers the hyphal apex. On the other hand, the polarisome components: SPA‐2, BUD‐6, MSB-3 and BNI‐1 showed that during early, unicellular developmental stages the filamentous fungal polarisome closely resembles the apical cap configuration known from yeasts. However during later, multicellular developmental stages all four polarisome components become spatiotemporally separated within the apical dome, and thus adopt a so far unknown configuration. Most notably, in vegetative hyphal tips MSB-3 colocalizes with the Spitzenkörper (Spk), BUD‐6 accumulates as a subapical cloud excluded from the Spk, whereas BNI‐1 and SPA‐2 partially colocalize with the Spk at the tip apex. Phenotypic analyses of gene deletion mutants revealed additional functions for BUD‐6 and BNI‐1 in septum formation, cytokinesis, cell fusion regulation, and the maintenance of Spk integrity. Considered together, our findings reveal that the components of the CDC-42 GTPase module and those of the polarisome are required to build a functional tip growth apparatus including the Spk in N. crassa.

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1 - CICESE, Microbiology, Carretera Ensenada Tijuana No 3918 Zona Playitas, Ensenada, B.C., 22860, Mexico

N. crassa
GTPase module

Presentation Type: Symposium or Colloquium Presentation
Session: SY6
Location: Room 104 AB/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 3:30 PM
Number: SY6006
Abstract ID:182
Candidate for Awards:None

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