The genome-scale binding profile of the CCAAT-binding complex in Aspergillus fumigatus

The CCAAT-binding complex (CBC) is a heterotrimetric transcription factor conserved in all eukaryotes. The CBC specifically interacts with the pentanucleotide motif known as the CCAAT box, which is one of the most ubiquitous cis-acting elements on the eukaryotic promoters. In Aspergillus fumigatus, the CBC consists of three subunits HapB, HapC, and HapE, which are all required for specific binding to the target sequences. This regulatory complex has been shown to be involved in the regulation of a wide range of cellular processes, including primary and secondary metabolism, iron homeostasis, as well as azole drug resistance and virulence in mammalian hosts. In this study, we investigated the genome-wide binding profile of the CBC using the chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq). We identified over 1,000 peak regions, which showed more than 5-fold enrichment compared to the input control in steady-state iron-replete (+Fe) and iron-starvation (-Fe) conditions. Bioinformatic analysis of the peak regions revealed the 5'-CSAATVR-3' sequence as the most enriched nucleotide motif, suggesting that this motif acts as the consensus binding sequence for the CBC in vivo. Overall design: Examination of genome-wide binding profiles of a C-terminally GFP tagged HapC protein in steady-state iron-replete (+Fe) and iron-starvation (-Fe) conditions with two biological replicates.