title: An S-acylation switch of conserved G domain cysteines is required for polarity signaling by ROP GTPases.
abstract: Rho GTPases are master regulators of cell polarity. For their function, Rhos must associate with discrete plasma membrane domains. Rho of Plants (ROPs) or RACs comprise a single family. Prenylation and S-acylation of hypervariable domain cysteines of Ras and Rho GTPases are required for their function; however, lipid modifications in the G domain have never been reported. Reversible S-acylation involves the attachment of palmitate (C16:0) or other saturated lipids to cysteines through a thioester linkage and was implicated in the regulation of signaling. Here we show that transient S-acylation of Arabidopsis AtROP6 takes place on two conserved G domain cysteine residues, C21 and C156. C21 is relatively exposed and is accessible for modification, but C156 is not, implying that its S-acylation involves a conformational change. Fluorescence recovery after photobleaching beam-size analysis shows that S-acylation of AtROP6 regulates its membrane-association dynamics, and detergent-solubilization studies indicate that it regulates AtROP6 association with lipid rafts. Site-specific acylation-deficient AtROP6 mutants can bind and hydrolyze GTP but display compromised effects on polar cell growth, endocytic uptake of the tracer dye FM4-64, and distribution of reactive oxygen species. These data reveal an S-acylation switch that regulates Rho signaling.
authors.affiliation: Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Nadav
authors.initials: N
authors.lastname: Sorek
authors.forename: Oshik
authors.initials: O
authors.lastname: Segev
authors.forename: Orit
authors.initials: O
authors.lastname: Gutman
authors.forename: Einat
authors.initials: E
authors.lastname: Bar
authors.forename: Sandra
authors.initials: S
authors.lastname: Richter
authors.forename: Limor
authors.initials: L
authors.lastname: Poraty
authors.forename: Joel A
authors.initials: JA
authors.lastname: Hirsch
authors.forename: Yoav I
authors.initials: YI
authors.lastname: Henis
authors.forename: Efraim
authors.initials: E
authors.lastname: Lewinsohn
authors.forename: Gerd
authors.initials: G
authors.lastname: Jürgens
authors.forename: Shaul
authors.initials: S
authors.lastname: Yalovsky
mesh_terms: D000215:Acylation; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D016764:Cell Polarity; D003545:Cysteine / Q000378:metabolism*; D050356:Lipid Metabolism; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D020559:Monomeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013229:Stearic Acids / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C518506:ROP6 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D013229:Stearic Acids; D019308:Palmitic Acid; C031183:stearic acid; D020559:Monomeric GTP-Binding Proteins; D003545:Cysteine