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bioRxiv · 10.1101/574772

G1/S transcription factors assemble in discrete clusters that increase in number as cells grow

Black, L.·Tollis, S.·Fiche, J.-B.·Dorsey, S.·Cheng, J.·Notley, S.·Crevier, B.·Bigness, J.·Nollmann, M.·Tyers, M.·Royer, C. A.
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Abstract

The spatio-temporal organization of transcription factor (TF)-promoter interactions is critical for the coordination of transcriptional programs. In budding yeast, the main G1/S transcription factors, SBF and MBF, are limiting with respect to target promoters in small G1 phase cells and accumulate as cells grow, raising the question of how SBF/MBF are dynamically distributed across the G1/S regulon. Super-resolution Photo-Activatable Localization Microscopy (PALM) mapping of the static positions of SBF/MBF subunits revealed that 85% were organized into discrete clusters containing [~]8 copies regardless of cell size, while the number of clusters increased with growth. Stochastic simulations with a mathematical model based on co-localization of promoters in clusters recapitulated observed cluster behavior. A prediction of the model that SBF/MBF should exhibit both fast and slow dynamics was confirmed in PALM experiments on live cells. This spatio-temporal organization of the TFs that activate the G1/S regulon may help coordinate commitment to division.

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Black, L., Tollis, S., Fiche, J.-B., Dorsey, S., Cheng, J., Notley, S., Crevier, B., Bigness, J., Nollmann, M., Tyers, M., Royer, C. A.. 2019-03-11. G1/S transcription factors assemble in discrete clusters that increase in number as cells grow. https://doi.org/10.1101/574772

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