THE CAPACITY OF ASPERGILLUS NIGER TO SENSE AND RESPOND TO CELL WALL STRESS REQUIRES AT LEAST THREE TRANSCRIPTION FACTORS: RLMA, MSNA AND CRZA

Transcriptomics signatures of Aspergillus niger were used to predict regulator proteins mediating the survival responses against these stressors and the phenotypes of selected null mutant strains were studied. 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 main compensatory response including RhoB, RhoD, MkkA and RlmA as regulator proteins. (ii) RlmA is the main transcription factor required for the protection against calcofluor white but cooperates with MsnA and CrzA to ensure survival of A. niger when challenged with caspofungin or aureobasidin A. All three transcription factors are important for these compensatory responses and involve induction of glucan and chitin synthesising genes amongst others. (iii) Membrane stress provoked by aureobasidin A via disturbance of sphingolipid synthesis induces cell wall stress in A. niger, but membrane stress provoked by fenpropimorph via disturbance of ergosterol synthesis does not. The present work uncovered different defence strategies of A. niger to protect itself against cell wall stress conditions. At least three transcription factors - RlmA, MsnA and CrzA – are employed in a well-balanced manner. The data also predicts a fourth transfactor, SrbA, which seems to be specifically important during fenpropimorph-induced cell membrane stress. Future studies will disclose how these regulators are interlocked in different signalling pathways to secure survival of A. niger under different cell wall stress conditions. This data set consists of 16 samples from 8 conditions (biological duplicates for each condition). The conditions cover treatment (4 conditions) and controls (3 conditions) of the Aspergillus niger wild type to 4 cell wall stresss inducing agents. Additionally, the data set comprises data (1 condition) for an Aspergillus niger mutant strain in which the RlmA transcription factor has been deleted. RlmA is responsible for the induction of cell wall stress response genes within the cell wall integrity pathway.