The Hypocrea jecorina HAP 2/3/5 protein complex binds to the inverted CCAAT-box (ATTGG) within the cbh2 (cellobiohydrolase II-gene) activating element

Abstract

The 5' regulatory region of the chh2 gene, encoding cellobiohydrolase II, of the filamentous fungus Hypocrea jecorina contains the cbh2 activating element (CAE) which is essential for cbh2 expression. The CAE consists of two separate, adjacent motifs, a CCAAT box on the template strand (ATTGG) and a GTAATA box on the coding strand, which co-operate in the induction of the gene by cellulose or sophorose. EMSA supershift experiments using an antibody against Aspergillus nidulans HAPC suggested that the complex which binds to the H. jecorina CCAAT box contains a HAPC homolog. To obtain direct evidence for this, we have cloned the hap2, hap3 and hap5 genes from H. jecorina. They encode proteins whose core regions display great similarity to Aspergillus HAPB, HAPC and HAPE and to known HAP homologs from other organisms. All three genes are transcribed in a carbon source-independent manner. A. nidulans deltahap strains were functionally complemented in vitro by the overexpressed H. jecorina HAP2, HAP3 and HAP5 proteins, and they thus represent subunits of the CCAAT-binding complex. Furthermore, all three proteins (HAP2, HAP3 and HAP5) were needed to bind to the CAE in the H. jecorina cbh2 gene promoter in vitro. We conclude that the CCAAT box on the template strand in CAE is bound by the H. jecorina equivalent of the HAP protein complex.

Unravelling the molecular basis for light modulated cellulase gene expression - the role of photoreceptors in Neurospora crassa

“…In T. reesei , cellulase regulation is affected by homologues of the HAP-complex [44], the transcriptional activator xyr1 [45] and repressor ace1 [46]. While neither the HAP-complex homologues nor the xyr1 homologue showed altered transcriptional patterns in the N. crassa photoreceptor mutants as compared to wild type, an ace1 homolog (NCU09333) showed increased expression levels in the Δ wc-2 mutant after 40 hrs.…”

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…In T. reesei, a complex HAP-like factor that binds to the CCAAT motif within the cellobiohydrolase II gene promoter (cbh2) has been identified; this complex contains the TFs Hap2/ Hap3/Hap5 (TR_124286, TR_121080, and TR_62979, respectively). In addition, these TFs are constitutively expressed, independently of the carbon source used for growth (887,1078). Orthology analyses showed that these TFs are conserved in T. reesei, T. atroviride, and T. virens (see Tables S1 and S2).…”

Regulation of Cellulase and Hemicellulase Gene Expression in Fungi

“…Thereby the action of acetyltransferases may play a role in the local disruption of nucleosomes since an association of GATA-1 and NF-Y with acetyltransferases p300/CBP has been shown [81, 82]. The corresponding hap2, hap3 and hap5 genes from T. reesei were cloned by Zeilinger et al [83] showing that they encode proteins similar to Hap homologues from other organisms and essential for binding to the CAE ( cbh2 -activating element) in the T. reesei cel6a promoter. The HAP2/3/5 complex is considered needed for generating an open chromatin structure required for full transcriptional activation [84].…”