HSP90/70 chaperones are required for rapid nucleosome removal upon induction of the GAL genes of yeast

Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2008; 105(8):2975-80. DOI: 10.1073/pnas.0800053105
Source: PubMed


Induction of transcription of the GAL genes of yeast by galactose is a multistep process: Galactose frees the activator Gal4 of its inhibitor, Gal80, allowing Gal4 to recruit proteins required to transcribe the GAL genes. Here, we show that deletion of components of either the HSP90 or the HSP70 chaperone machinery delays this induction. This delay remains when the galactose-signaling pathway is bypassed, and it cannot be explained by a chaperone requirement for DNA binding by Gal4. Removal of promoter-bound nucleosomes is delayed in a chaperone mutant, and our findings suggest an involvement of HSP90 and HSP70 in this early step in gene induction.

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Available from: Monique Floer, Jan 19, 2015
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    • "If HSP90A was repressing HSF1 activity, its interaction with HSF1 would be expected to be disrupted soon after the onset of stress (Zou et al., 1998). Perhaps the constitutive interaction of HSF1 with HSP90A/HSP70A is required for nucleosome removal during transactivation, or for the maximal activation of paused polymerase II, as suggested previously (Floer et al., 2008; Sawarkar et al., 2012)? Apparently in favor of a role for HSP90A in controlling HSF1 activity is the observation that feeding of HSP90 inhibitors geldanamycin and radicicol elicited a stress response (Figure 5 and Supplemental Figure 1B). "
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