ChIP-seq and In Vivo Transcriptome Analyses of the Aspergillus fumigatus SREBP SrbA Reveals a New Regulator of the Fungal Hypoxia Response and Virulence
Figure 12
Working models for transcriptional regulation of the hypoxia response by SrbA and SrbB in A. fumigatus.
A. fumigatus SREBPs, SrbA and SrbB have dependent and independent functions in regulation of hypoxic genes involved in ergosterol biosynthesis, carbohydrate metabolism, heme biosynthesis, and nitrate assimilation. In response to hypoxia, srbB transcription is induced earlier than srbA (15 minutes in hypoxia) possibly by an unknown factor (marked as ‘X’). SrbA regulates srbB and its own transcript abundance. Similarly, SrbB regulates srbA and its own transcript abundance. qRT-PCR and ChIP-qPCR data presented in this study show that abundance of erg1, erg25A, hem13, niiA, and alcC is regulated by both SrbA and SrbB. In contrast, abundance of erg11A, erg3B, erg5, and niaD is dependent on SrbA. SrbB appears to have a dominant function over SrbA in regulation of hem13 and alcC transcript abundance (indicated by dotted lines).