title: Yeast translation elongation factor-1A binds vacuole-localized Rho1p to facilitate membrane integrity through F-actin remodeling.
abstract: Rho GTPases are molecular switches that modulate a variety of cellular processes, most notably those involving actin dynamics. We have previously shown that yeast vacuolar membrane fusion requires re-organization of actin filaments mediated by two Rho GTPases, Rho1p and Cdc42p. Cdc42p initiates actin polymerization to facilitate membrane tethering; Rho1p has a role in the late stages of vacuolar fusion, but its mode of action is unknown. Here, we identified eEF1A as a vacuolar Rho1p-interacting protein. eEF1A (encoded by the TEF1 and TEF2 genes in yeast) is an aminoacyl-tRNA transferase needed during protein translation. eEF1A also has a second function that is independent of translation; it binds and organizes actin filaments into ordered cable structures. Here, we report that eEF1A interacts with Rho1p via a C-terminal subdomain. This interaction occurs predominantly when both proteins are in the GDP-bound state. Therefore, eEF1A is an atypical downstream effector of Rho1p. eEF1A does not promote vacuolar fusion; however, overexpression of the Rho1p-interacting subdomain affects vacuolar morphology. Vacuoles were destabilized and prone to leakage when treated with the eEF1A inhibitor narciclasine. We propose a model whereby eEF1A binds to Rho1p-GDP on the vacuolar membrane; it is released upon Rho1p activation and then bundles actin filaments to stabilize fused vacuoles. Therefore, the Rho1p-eEF1A complex acts to spatially localize a pool of eEF1A to vacuoles where it can readily organize F-actin.
authors.affiliation: From the Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: James A R
authors.initials: JAR
authors.lastname: Bodman
authors.affiliation: From the Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: From the Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Logan
authors.affiliation: From the Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. Electronic address: gary.eitzen@ualberta.ca.
authors.forename: Gary
authors.initials: G
authors.lastname: Eitzen
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D029701:Saccharomyces cerevisiae Proteins; C410826:TEF1 protein, S cerevisiae; C057183:TEF2 protein, S cerevisiae; C051302:RHO1 protein, S cerevisiae; D020741:rho GTP-Binding Proteins
keywords: Actin; Membrane Fusion; Ras Homolog Gene Family, Member A (RhoA); Subcellular Organelle; Vacuole; Yeast