Isolation of genes encoding novel transcription factors which interact with the Hap complex from Aspergillus species

Abstract The Saccharomyces cerevisiae CCAAT-binding factor is composed of four subunits Hap2p, Hap3p, Hap4p and Hap5p. Three subunits, Hap2/3/5p, are required for DNA-binding and Hap4p is involved in transcriptional activation. Although homologues of Hap2/3/5p (in the case of Aspergillus nidulans ; HapB/C/E, respectively) were found in many eukaryotes, no Hap4p homologues have been found except for the other yeast, Kluyveromyces lactis . With the lexA-hap2 , - hapB , - hapC , or - hapE fusion gene, we evaluated the ability of interaction between Aspergillus Hap subunits and S. cerevisiae Hap4p subunit in S. cerevisiae . Using the system with lexA-hapB , a gene encoding a novel transcriptional activator, which interacted with the Hap complex, was isolated from A. nidulans and designated hapX .