engleski

Abolishing rapid degradation of non-coding transcripts delays transcriptional activation of yeast PHO5 gene

Budding yeast PHO5 promoter is a classical paradigm for promoter regulation through chromatin remodeling. Upon induction, PHO5 promoter chromatin structure undergoes a massive transition, which requires action of a large network of chromatin modifiers and remodelers. The complete remodeler set involved at this promoter was recently characterized: five chromatin remodelers from four different remodeler families cooperate in this process, RSC complex being the major one (1, 2). Non-coding RNAs (ncRNAs) recently emerged as important regulators of chromatin structure in budding yeast, functioning mostly in cis by increasing recruitment of modifiers and remodelers. Strand-specific RNA tilling array data show transcription of two ncRNA species at the PHO5 locus under transcriptional repression: one transcribed in the antisense direction through most of the ORF and the promoter and other transcribed in the sense direction through the promoter. We are now exploring the role of non-coding transcription in regulation of PHO5 gene expression. To address this question, we utilized a mutant contex in which rapid degradation of ncRNAs is abolished by interfering with the activity of RNA exosome complex, which normally eliminates them. We found that depletion of the nuclear-specific catalytic exosome subunit Rrp6 leads to delayed transcriptional activation of PHO5 gene under inducing conditions. Additionally, similar effect is also observed upon depletion of exosome cofactor Rrp47. Results also indicate that this effect is manifested at the level of transcriptional initiation, as physiological transcriptional activation kinetics could be restored by overexpression of PHO5 transactivator Pho4. 1. Musladin, S., Krietenstein, N., Korber, P., Barbaric, S. (2014). The RSC chromatin remodeling complex has a crucial role in the complete remodeler set for yeast PHO5 promoter opening. Nucleic acids research, 42(7), 4270-4282. 2. Musladin, S., Novacic, A., Lieleg, C., Walker, M., Korber, P., Barbaric, S. (in preparation)

PHO5 ; RNA exosome ; antisense RNA ; Rrp6

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