Velvet domain protein VosA represses the zinc cluster transcription factor SclB regulatory network for Aspergillus nidulans asexual development, oxidative stress response and secondary metabolism.

The NF-kappa B-like velvet domain protein VosA (viability of spores) binds to more than 1,500 promoter sequences in the filamentous fungus Aspergillus nidutans. VosA inhibits premature induction of the developmental activator gene brlA, which promotes asexual spore formation in response to environmental cues as light. VosA represses a novel genetic network controlled by the scIB gene. Bfunction is antagonistic to VosA, because it induces the expression of early activator genes of asexual differentiation as flbC and flbD as well as brlA. The ScIB controlled network promotes asexual development and spore viability, but is independent of the fungal light control. ScIB interactions with the RcoA transcriptional repressor subunit suggest additional inhibitory functions on transcription. ScIB links asexual spore formation to the synthesis of secondary metabolites including emericellamides, austinol as well as dehydroaustinol and activates the oxidative stress response of the fungus. The fungal VosA-ScIB regulatory system of transcription includes a VosA control of the scIB promoter, common and opposite VosA and ScIB control functions of fungal development and several additional regulatory genes. The relationship between VosA and ScIB illustrates the presence of a convoluted surveillance apparatus of transcriptional control, which is required for accurate fungal development and the linkage to the appropriate secondary metabolism.