Naslov
Protein-protein and protein-DNA interactions in the regulation of the yeast PHO5 promoter

Autori
Barbarić, Slobodan

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Godišnji sastanak hrvatskih biokemičara, 1998 / Glavaš-Obrovac, Ljubica - Zagreb : Farmaceutsko-biokemijski fakultet Sveučilišta u Zagrebu, 1998, 36-36

Skup
Godišnji sastanak hrvatskih biokemičara

Mjesto i datum
Bizovačke Toplice, Hrvatska, 17.09.1998. - 20.09.1998

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
Transcriptional regulation; PHO5; Saccharomyces cerevisiae

Sažetak
The expression of the PHO5 gene in Saccharomyces cerevisiae, which encodes for a secreted acid phosphatase, is strongly repressed in phosphate-rich media. Two transcriptional factors, the basic helix-loop-helix protein Pho4 and homeodomain protein Pho2 are required for transcriptional activation of the PHO5 promoter upon phosphate starvation. The activity of Pho4 is regulated through phosphorylation by a cyclin-cdk complex, encoded by PHO80 and PHO85, respectively. Under repressing conditions, Pho4 is phosphorylated and located predominantly in cytoplasm showing that phosphorylation regulates the nuclear localisation of Pho4. Pho4 acts through two essential binding sites at the PHO5 promoter corresponding to regulatory elements UASp1 and UASp2. Multiple Pho2 binding sites adjacent to Pho4 sites were mapped, and by mutating Pho2 sites individually or in combination, it was shown that each of them contributes to PHO5 promoter activity. Their primary function is to recruit Pho4 to the promoter through cooperative interactions with Pho2. Cooperativity requires DNA binding of both proteins and specific Pho2-Pho4 interactions. A Pho4 derivative lacking the Pho2 interaction domain is unable to activate promoter, but testing UAS elements individually in a heterologous promoter reveals striking difference between the two elements. UASp1 is fully inactive, indicating no binding of the Pho4 derivative to this site, but UASp2 activates strongly in Pho2 independent manner. These activity measurements and in vivo footprinting experiments reveal that cooperative Pho2-Pho4 interactions at the PHO5 promoter are critically required for Pho4 binding to UASp1, while at UASp2, Pho2 is mainly required for the ability of Pho4 to transactivate.

Izvorni jezik
Engleski

Znanstvena područja
Prehrambena tehnologija

POVEZANOST RADA