title: Co-delivery of cell-wall-forming enzymes in the same vesicle for coordinated fungal cell wall formation.
abstract: Fungal cells are surrounded by an extracellular cell wall. This complex matrix of proteins and polysaccharides protects against adverse stresses and determines the shape of fungal cells. The polysaccharides of the fungal wall include 1,3-β-glucan and chitin, which are synthesized by membrane-bound synthases at the growing cell tip. A hallmark of filamentous fungi is the class V chitin synthase, which carries a myosin-motor domain. In the corn smut fungus Ustilago maydis, the myosin-chitin synthase Mcs1 moves to the plasma membrane in secretory vesicles, being delivered by kinesin-1 and myosin-5. The myosin domain of Mcs1 enhances polar secretion by tethering vesicles at the site of exocytosis. It remains elusive, however, how other cell-wall-forming enzymes are delivered and how their activity is coordinated post secretion. Here, we show that the U. maydis class VII chitin synthase and 1,3-β-glucan synthase travel in Mcs1-containing vesicles, and that their apical secretion depends on Mcs1. Once in the plasma membrane, anchorage requires enzyme activity, which suggests co-synthesis of chitin and 1,3-β-glucan polysaccharides at sites of exocytosis. Thus, delivery of cell-wall-forming enzymes in Mcs1 vesicles ensures local foci of fungal cell wall formation.
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Martin
authors: M
authors: Schuster
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Magdalena
authors: M
authors: Martin-Urdiroz
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Yujiro
authors: Y
authors: Higuchi
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Christian
authors: C
authors: Hacker
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Sreedhar
authors: S
authors: Kilaru
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Sarah J
authors: SJ
authors: Gurr
authors: Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
authors: Gero
authors: G
authors: Steinberg
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology* / Q000502:physiology*; D002686:Chitin / Q000378:metabolism; D002687:Chitin Synthase / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D022142:Secretory Vesicles / Q000737:chemistry / Q000378:metabolism*; D014588:Ustilago / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D047071:beta-Glucans / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D047071:beta-Glucans; D002686:Chitin; C033363:beta-1,3-glucan; D005964:Glucosyltransferases; D002687:Chitin Synthase; C020570:1,3-beta-glucan synthase; D009218:Myosins