title: NPFXD-mediated endocytosis is required for polarity and function of a yeast cell wall stress sensor.
abstract: The actin-associated protein Sla1p, through its SHD1 domain, acts as an adaptor for the NPFX(1,2)D endocytic targeting signal in yeast. Here we report that Wsc1p, a cell wall stress sensor, depends on this signal-adaptor pair for endocytosis. Mutation of NPFDD in Wsc1p or expression of Sla1p lacking SHD1 blocked Wsc1p internalization. By live cell imaging, endocytically defective Wsc1p was not concentrated at sites of endocytosis. Polarized distribution of Wsc1p to regions of cell growth was lost in the absence of endocytosis. Mutations in genes necessary for endosome to Golgi traffic caused redistribution of Wsc1p from the cell surface to internal compartments, indicative of recycling. Inhibition of Wsc1p endocytosis caused defects in polarized deposition of the cell wall and increased sensitivity to perturbation of cell wall synthesis. Our results reveal that the NPFX(1,2)D-Sla1p system is responsible for directing Wsc1p into an endocytosis and recycling pathway necessary to maintain yeast cell wall polarity. The dynamic localization of Wsc1p, a sensor of the extracellular wall in yeast, resembles polarized distribution of certain extracellular matrix-sensing integrins through endocytic recycling.
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Hai Lan
authors.initials: HL
authors.lastname: Piao
authors.forename: Iara M P
authors.initials: IM
authors.lastname: Machado
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Payne
mesh_terms: D020816:Amino Acid Motifs; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins; D004705:Endocytosis; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C082265:SLA1 protein, S cerevisiae; C119383:SLG1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins