title: A role for GEA1 and GEA2 in the organization of the actin cytoskeleton in Saccharomyces cerevisiae.
abstract: Profilin is an actin monomer-binding protein implicated in the polymerization of actin filaments. In the budding yeast Saccharomyces cerevisiae, the pfy1-111 rho2delta double mutant has severe growth and actin cytoskeletal defects. The GEA1 and GEA2 genes, which code for paralog guanosine exchange factors for Arf proteins, were identified as multicopy suppressors of the mutant phenotype. These two genes restored the polarized distribution of actin cortical patches and produced visible actin cables in both the pfy1-111 rho2delta and pfy1delta cells. Thus, overexpression of GEA1 or GEA2 bypassed the requirement for profilin in actin cable formation. In addition, gea1 gea2 double mutants showed defects in budding and in actin cytoskeleton organization, while overexpression of GEA1 or GEA2 led to the formation of supernumerary actin cable-like structures in a Bni1p/Bnr1p-dependent manner. The ADP-ribosylation factor Arf3p may be a target of Gea1p/Gea2p, since overexpression of ARF3 partially suppressed the profilin-deficient phenotype and a deletion of ARF3 exacerbated the phenotype of a pfy1-111 mutant. Gea1p, Gea2p, Arf1p, and Arf2p but not Arf3p are known to function in vesicular transport between the endoplasmic reticulum and the Golgi. In this work, we demonstrate a role for Gea1p, Gea2p, and Arf3p in the organization of the actin cytoskeleton.
authors.affiliation: Centre de Recherche sur la Structure, la Fonction et l'Ingénierie des Protéines, Pavillon Charles-Eugène Marchand, Université Laval, Ste-Foy, Québec G1K 7P4, Canada.
authors.forename: Ewa
authors.initials: E
authors.lastname: Zakrzewska
authors.forename: Marjorie
authors.initials: M
authors.lastname: Perron
authors.forename: André
authors.initials: A
authors.lastname: Laroche
authors.forename: Dominick
authors.initials: D
authors.lastname: Pallotta
mesh_terms: D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000502:physiology*; D000199:Actins / Q000378:metabolism*; D001483:Base Sequence; D003599:Cytoskeleton / Q000378:metabolism*; D017931:DNA Primers; D005800:Genes, Fungal; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*
chemical_list: D000199:Actins; D017931:DNA Primers; C102475:GEA1 protein, S cerevisiae; C121632:GEA2 protein, S cerevisiae; D020662:Guanine Nucleotide Exchange Factors; D029701:Saccharomyces cerevisiae Proteins; C492128:ARF3 protein, S cerevisiae; D020727:ADP-Ribosylation Factors