title: Class I and class II chitin synthases are involved in septum formation in the filamentous fungus Aspergillus nidulans.
abstract: The class II and class I chitin synthases of the filamentous fungus Aspergillus nidulans are encoded by chsA and chsC, respectively. Previously, we presented several lines of evidence suggesting that ChsA and ChsC have overlapping functions in maintaining cell wall integrity. In order to determine the functions of these chitin synthases, we employed electron and fluorescence microscopy and investigated in detail the cell wall of a DeltachsA DeltachsC double mutant (DeltaAC mutant) along with the localization of ChsA and ChsC. In the lateral cell wall of the DeltaAC mutant, electron-transparent regions were thickened. Septa of the DeltaAC mutant were aberrantly thick and had a large pore. Some septa were located abnormally close to adjacent septa. A functional hemagglutinin (HA)-tagged ChsA (HA-ChsA) and a functional FLAG-tagged ChsC (FLAG-ChsC) were each localized to a subset of septation sites. Comparison with the localization pattern of actin, which is known to localize at forming septa, suggested that ChsA and ChsC transiently exist at the septation sites during and shortly after septum formation. Double staining of HA-ChsA and FLAG-ChsC indicated that their localizations were not identical but partly overlapped at the septation sites. Fluorescence of FLAG-ChsC, but not of HA-ChsA, was also observed at hyphal tips. These data indicate that ChsA and ChsC share overlapping roles in septum formation.
authors.affiliation: Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ichinomiya
authors.forename: Emi
authors.initials: E
authors.lastname: Yamada
authors.forename: Shuichi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Akinori
authors.initials: A
authors.lastname: Ohta
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Horiuchi
mesh_terms: D000199:Actins / Q000378:metabolism; D001233:Aspergillus nidulans / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D015153:Blotting, Western; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D002687:Chitin Synthase / Q000737:chemistry / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006388:Hemagglutinins / Q000737:chemistry; D025301:Hyphae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D007211:Indoles; D008856:Microscopy, Fluorescence; D009154:Mutation; D009842:Oligopeptides; D010455:Peptides / Q000737:chemistry
chemical_list: D000199:Actins; D005456:Fluorescent Dyes; D005656:Fungal Proteins; D006388:Hemagglutinins; D007211:Indoles; D009842:Oligopeptides; D010455:Peptides; C007293:DAPI; C085706:FLAG peptide; D002687:Chitin Synthase; D016650:Fluorescein-5-isothiocyanate