PT  - JOURNAL ARTICLE
AU  - Adam J. M. Wollman
AU  - Sviatlana Shashkova
AU  - Erik G. Hedlund
AU  - Rosmarie Friemann
AU  - Stefan Hohmann
AU  - Mark C. Leake
TI  - Transcription factor clusters regulate genes in eukaryotic cells
AID  - 10.1101/125104
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 125104
4099  - http://biorxiv.org/content/early/2017/04/06/125104.short
4100  - http://biorxiv.org/content/early/2017/04/06/125104.full
AB  - Transcription is regulated through binding factors to gene promoters to activate or repress expression, however, the mechanisms by which factors find targets remain unclear. Using single-molecule fluorescence microscopy, we determined in vivo stoichiometry and spatiotemporal dynamics of a GFP tagged repressor, Mig1, from a paradigm signaling pathway of Saccharomyces cerevisiae. We find the repressor operates in clusters, which upon extracellular signal detection, translocate from the cytoplasm, bind to nuclear targets and turnover. Simulations of Mig1 configuration within a 3D yeast genome model combined with a promoter-specific, fluorescent translation reporter confirmed clusters are the functional unit of gene regulation. In vitro and structural analysis on reconstituted Mig1 suggests that clusters are stabilized by depletion forces between intrinsically disordered sequences. We observed similar clusters of a co-regulatory activator from a different pathway, supporting a generalized cluster model for transcription factors that reduces promoter search times through intersegment transfer while stabilizing gene expression.