title: Dissecting the function of the different chitin synthases in vegetative growth and sexual development in Neurospora crassa.
abstract: Chitin, one of the most important carbohydrates of the fungal cell wall, is synthesized by chitin synthases (CHS). Seven sequences encoding CHSs have been identified in the genome of Neurospora crassa. Previously, CHS-1, -3 and -6 were found at the Spitzenkörper(Spk) core and developing septa. We investigated the functional importance of each CHS in growth and development of N. crassa. The cellular distribution of each CHS tagged with fluorescent proteins and the impact of corresponding gene deletions on vegetative growth and sexual development were compared. CHS-2, -4, -5 and -7 were also found at the core of the Spk and in forming septa in vegetative hyphae. As the septum ring developed, CHS-2-GFP remained at the growing edge of the septum until it localized around the septal pore. In addition, all CHSs were located in cross-walls of conidiophores. A partial co-localization of CHS-1-m and CHS-5-GFP or CHS-2-GFP occurred in the Spk and septa. Analyses of deletion mutants suggested that CHS-6 has a role primarily in hyphal extension and ascospore formation, CHS-5 in aerial hyphae, conidia and ascospore formation, CHS-3 in perithecia development and CHS-7 in all of the aforementioned. We show that chs-7/csmB fulfills a sexual function and chs-6/chsG fulfills a vegetative growth function in N. crassa but not in Aspergillus nidulans, whereas vice versa chs-2/chsA fulfills a sexual function in A. nidulans but not in N. crassa. This suggests that different classes of CHSs can fulfill distinct developmental functions in various fungi. Immunoprecipitation followed by mass spectrometry of CHS-1-GFP, CHS-4-GFP and CHS-5-GFP identified distinct putative interacting proteins for each CHS. Collectively, our results suggest that there are distinct populations of chitosomes, each carrying specific CHSs, with particular roles during different developmental stages.
authors.affiliation: Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada, CICESE, Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California C.P. 22860, Mexico.
authors.forename: Rosa A
authors.initials: RA
authors.lastname: Fajardo-Somera
authors.affiliation: Department of Molecular Microbiology and Genetics, Georg-August Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Jöhnk
authors.affiliation: Department of Molecular Microbiology and Genetics, Georg-August Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
authors.forename: Özgür
authors.initials: Ö
authors.lastname: Bayram
authors.affiliation: Department of Molecular Microbiology and Genetics, Georg-August Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Valerius
authors.affiliation: Department of Molecular Microbiology and Genetics, Georg-August Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
authors.forename: Gerhard H
authors.initials: GH
authors.lastname: Braus
authors.affiliation: Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada, CICESE, Ctra. Ensenada-Tijuana No. 3918, Ensenada, Baja California C.P. 22860, Mexico. Electronic address: riquelme@cicese.mx.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Riquelme
mesh_terms: D001233:Aspergillus nidulans / Q000235:genetics; D002687:Chitin Synthase / Q000502:physiology*; D022162:Cytoplasmic Vesicles / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics; D005838:Genotype; D049452:Green Fluorescent Proteins / Q000235:genetics; D025301:Hyphae / Q000254:growth & development / Q000648:ultrastructure; D047468:Immunoprecipitation; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D013172:Spores, Fungal / Q000254:growth & development; D053719:Tandem Mass Spectrometry
chemical_list: D005656:Fungal Proteins; D049452:Green Fluorescent Proteins; D002687:Chitin Synthase; C400821:chitin synthase 2
keywords: Cell wall; Chitin synthase; Hyphal morphogenesis; Proteomics; Sexual development; Spitzenkörper