Altering the expression of two chitin synthase genes differentially affects the growth and morphology of Aspergillus oryzae

• Published in: Microbiology (Society for General Microbiology) Vol. 148; no. 12; pp. 4025 - 4033
• Main Authors: Muller, Christian, Hjort, Carsten M, Hansen, Kim, Nielsen, Jens
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.12.2002; Society for General Microbiology
• Subjects: Aspergillus nidulans; Aspergillus oryzae; Aspergillus oryzae - enzymology; Aspergillus oryzae - genetics; Aspergillus oryzae - growth & development; Aspergillus oryzae - ultrastructure; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Cell Wall - chemistry; Chitin - analysis; chitin synthase; Chitin Synthase - chemistry; Chitin Synthase - genetics; Chitin Synthase - metabolism; chsB gene; chsC gene; csmA gene; Culture Media; dniiA gene; Fundamental and applied biological sciences. Psychology; Gene Deletion; Gene Expression Regulation, Fungal; Genetic Engineering - methods; Glucans - analysis; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Microbiology; Molecular Sequence Data; Morphology, structure, chemical composition; Mycology; Sequence Analysis, DNA; Transcription, Genetic; Growth rate; Enzyme; Transferases; Glycosyltransferases; Synthase; Chitin synthase; Gene expression; Cell wall; Fungi; Aspergillus oryzae; Morphology; Hexosyltransferases; Fungi Imperfecti; Thallophyta
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-148-12-4025

Center for Process Biotechnology, BioCentrum-DTU building, 223, Søltofts Plads, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark 1 Novozymes A/S, 2880 Bagsværd, Denmark 2 Author for correspondence: Jens Nielsen. Tel: +45 4525 2696. Fax: +45 4588 4148. e-mail: jn{at}biocentrum.dtu.dk In Aspergillus oryzae , one full-length chitin synthase ( chsB ) and fragments of two other chitin synthases ( csmA and chsC ) were identified. The deduced amino acid sequence of chsB was similar (87% identity) to chsB from Aspergillus nidulans , which encodes a class III chitin synthase. The sequence obtained for csmA indicated that it had high similarity to class V chitin synthases. chsB and csmA disruption strains and a strain in which chsB transcription was controlled were constructed using the nitrite reductase ( niiA ) promoter. The strains were examined during hyphal growth by Northern analysis, analysis of the cell-wall composition and growth in the presence of Calcofluor white (CFW). The chsB disrupted strain and the uninduced p niiA – chsB strain exhibited hyperbranching, they had a lower level of conidiation than the wild-type and were sensitive to CFW at 50 mg l -1 . When chsB transcription was induced in the strain containing the p niiA – chsB construct, the strain displayed wild-type morphology on solid medium and at sub-maximum growth rates but the wild-type morphology was not fully restored during rapid growth in batch cultivation. The csmA disruption strain displayed morphological abnormalities, such as ballooning cells, intrahyphal hyphae and conidial scars. The growth was severely inhibited in the presence of 10 mg CFW l -1 . In none of the constructed strains did the cell-wall composition differ from the wild-type. Northern analysis indicated no change in the transcription of the chitin synthase genes csmA and chsC when chsB expression was altered, and there was no change in the transcription of chsB and chsC when csmA was disrupted. Keywords: N -acetylglucosamine, cell wall Abbreviations: CFW, Calcofluor white The GenBank accession numbers for the chsB , chsC and chsA gene sequences reported in this paper are AY029261 , AF410464 and AF429307 , respectively.