title: Localization and role of MYO-1, an endocytic protein in hyphae of Neurospora crassa.
abstract: The subapical endocytic collar is a prominent feature of hyphae of Neurospora crassa. It comprises a dynamic collection of actin patches associated with a number of proteins required for endocytosis, namely, ARP-2/3 complex, fimbrin, coronin, etc. We presently show that MYO-1 is another key component of this endocytic collar. A myo-1 sequence was identified in the genome of N. crassa and used it to generate a strain with a myo-1-sgfp allele under the ccg1 promoter. Examination of living hyphae by confocal microscopy, revealed MYO-1-GFP located mainly as a dynamic collection of small patches arranged in collar-like fashion in the hyphal subapex. Dual tagging showed MYO-1-GFP partially colocalized with two other endocytic proteins, fimbrin and coronin. MYO-1 was also present during septum formation. By recovering a viable strain, albeit severely inhibited, after deletion of myo-1, it was possible to investigate the phenotypic consequences of the elimination of MYO-1. Deletion of myo-1 caused a severe reduction in growth rate (95%), near absence of aerial mycelium and no conidiation. A reduced uptake of the lipophilic dye FM4-64 indicated a deficiency in endocytosis in the Δmyo-1 mutant. Hyphae were produced by the Δmyo-1 mutant but their morphogenesis was severely affected; hyphal morphology was distorted displaying irregular periods of isotropic and polarized growth. The morphological alterations were accompanied, and presumably caused, by a disruption in the organization and dynamics of a myosin-deprived actin cytoskeleton that, ultimately, compromised the stability and function of the Spitzenkörper as a vesicle supply center.
authors.affiliation: Departamento de Microbiología, División de Biología Experimental y Aplicada, Centro de Investigación Científica y Educación Superior de Ensenada, Mexico.
authors.forename: Fernando
authors.initials: F
authors.lastname: Lara-Rojas
authors.affiliation: Departamento de Microbiología, División de Biología Experimental y Aplicada, Centro de Investigación Científica y Educación Superior de Ensenada, Mexico.
authors.forename: Salomón
authors.initials: S
authors.lastname: Bartnicki-García
authors.affiliation: Departamento de Microbiología, División de Biología Experimental y Aplicada, Centro de Investigación Científica y Educación Superior de Ensenada, Mexico. Electronic address: rmourino@cicese.mx.
authors.forename: Rosa R
authors.initials: RR
authors.lastname: Mouriño-Pérez
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D004705:Endocytosis; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D016681:Genome, Fungal; D049452:Green Fluorescent Proteins; D025301:Hyphae / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D009024:Morphogenesis; D009154:Mutation; D009218:Myosins / Q000235:genetics* / Q000378:metabolism*; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D010641:Phenotype; D013172:Spores, Fungal / Q000502:physiology
chemical_list: D005656:Fungal Proteins; D049452:Green Fluorescent Proteins; D009218:Myosins
keywords: Endocytosis; MYO-1; Morphogenesis; Myosin; Neurospora crassa; Polarized growth