Aramayo R, Timberlake W E
Department of Genetics, University of Georgia, Athens 30602.
EMBO J. 1993 May;12(5):2039-48. doi: 10.1002/j.1460-2075.1993.tb05853.x.
The developmentally regulated Aspergillus nidulans yA gene encodes a p-diphenol oxidase that is needed for synthesis of green conidial pigment. We subjected the yA 5' flanking region to mutational analysis in A. nidulans and Saccharomyces cerevisiae to identify DNA sequence elements involved in its transcriptional control, and identified two functionally distinct elements. Element I contained potential BrlA binding sites and was required for full level yA transcription, but not for developmental regulation in the presence of element II. Element II contained putative TEF-1 binding sites flanking a CCAAT element and was sufficient for developmental regulation of transcription. Mutation of the TEF-1 binding sites eliminated developmental regulation, whereas mutation of the CCAAT element led to elevated levels of transcription. Element II was also sufficient to induce transcription in S. cerevisiae when the A.nidulans developmental regulatory gene abaA was expressed from the GAL1 promoter. As AbaA and TEF-1 possess similar DNA binding domains, the abaA-yA interaction in yeast is probably direct. Thus, abaA appears to be a direct activator of yA, but yA regulation may also involve interactions with BrlA and a member of the CCAAT class of DNA binding proteins.
发育调控的构巢曲霉yA基因编码一种对合成绿色分生孢子色素所必需的对二酚氧化酶。我们对构巢曲霉和酿酒酵母中的yA 5'侧翼区域进行了突变分析，以鉴定参与其转录调控的DNA序列元件，并鉴定出两个功能不同的元件。元件I包含潜在的BrlA结合位点，是yA转录达到完全水平所必需的，但在元件II存在时对发育调控不是必需的。元件II包含围绕一个CCAAT元件的推定的TEF-1结合位点，并足以进行转录的发育调控。TEF-1结合位点的突变消除了发育调控，而CCAAT元件的突变导致转录水平升高。当构巢曲霉发育调控基因abaA从GAL1启动子表达时，元件II也足以在酿酒酵母中诱导转录。由于AbaA和TEF-1具有相似的DNA结合结构域，酵母中的abaA-yA相互作用可能是直接的。因此，abaA似乎是yA的直接激活因子，但yA调控也可能涉及与BrlA和CCAAT类DNA结合蛋白成员的相互作用。
