The capacity of Aspergillus niger to sense and respond to cell wall stress requires at least three transcription factors: RlmA, MsnA and CrzA.

Autor: Fiedler MR; Institute of Biotechnology, Department Applied and Molecular Microbiology Berlin University of Technology, Gustav-Meyer-Allee 25, Berlin, D-13355 Germany., Lorenz A; Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, Sylviusweg 72, Leiden, 2333 BE The Netherlands., Nitsche BM; Institute of Biotechnology, Department Applied and Molecular Microbiology Berlin University of Technology, Gustav-Meyer-Allee 25, Berlin, D-13355 Germany.; Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, Sylviusweg 72, Leiden, 2333 BE The Netherlands., van den Hondel CA; HiTeXacoat, Waterlelie 124, Gouda, 2804 PZ The Netherlands., Ram AF; Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, Sylviusweg 72, Leiden, 2333 BE The Netherlands.; Kluyver Centre for Genomics of Industrial Fermentation, Delft, 2600 GA The Netherlands., Meyer V; Institute of Biotechnology, Department Applied and Molecular Microbiology Berlin University of Technology, Gustav-Meyer-Allee 25, Berlin, D-13355 Germany.; Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, Sylviusweg 72, Leiden, 2333 BE The Netherlands.; Kluyver Centre for Genomics of Industrial Fermentation, Delft, 2600 GA The Netherlands.
Jazyk: angličtina
Zdroj: Fungal biology and biotechnology [Fungal Biol Biotechnol] 2014 Dec 01; Vol. 1, pp. 5. Date of Electronic Publication: 2014 Dec 01 (Print Publication: 2014).
DOI: 10.1186/s40694-014-0005-8
Abstrakt: Background: Cell wall integrity, vesicle transport and protein secretion are key factors contributing to the vitality and productivity of filamentous fungal cell factories such as Aspergillus niger . In order to pioneer rational strain improvement programs, fundamental knowledge on the genetic basis of these processes is required. The aim of the present study was thus to unravel survival strategies of A. niger when challenged with compounds interfering directly or indirectly with its cell wall integrity: calcofluor white, caspofungin, aureobasidin A, FK506 and fenpropimorph.
Results: Transcriptomics signatures of A. niger and phenotypic analyses of selected null mutant strains were used to predict regulator proteins mediating the survival responses against these stressors. This integrated approach allowed us to reconstruct a model for the cell wall salvage gene network of A. niger that ensures survival of the fungus upon cell surface stress. The model predicts that (i) caspofungin and aureobasidin A induce the cell wall integrity pathway as a main compensatory response via induction of RhoB and RhoD, respectively, eventually activating the mitogen-activated protein kinase kinase MkkA and the transcription factor RlmA. (ii) RlmA is the main transcription factor required for the protection against calcofluor white but it cooperates with MsnA and CrzA to ensure survival of A. niger when challenged with caspofungin and aureobasidin A. (iii) Membrane stress provoked by aureobasidin A via disturbance of sphingolipid synthesis induces cell wall stress, whereas fenpropimorph-induced disturbance of ergosterol synthesis does not.
Conclusion: The present work uncovered a sophisticated defence system of A. niger which employs at least three transcription factors - RlmA, MsnA and CrzA - to protect itself against cell wall stress. The transcriptomic data furthermore predicts a fourth transfactor, SrbA, which seems to be specifically important to survive fenpropimorph-induced cell membrane stress. Future studies will disclose how these regulators are interlocked in different signaling pathways to secure survival of A. niger under different cell wall stress conditions.
Databáze: MEDLINE
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