RT Journal Article SR Electronic T1 Dynamic multifactor hubs interact transiently with sites of active transcription in Drosophila embryos JF bioRxiv FD Cold Spring Harbor Laboratory SP 377812 DO 10.1101/377812 A1 Mustafa Mir A1 Michael R. Stadler A1 Stephan A. Ortiz A1 Melissa M. Harrison A1 Xavier Darzacq A1 Michael B. Eisen YR 2018 UL http://biorxiv.org/content/early/2018/07/26/377812.abstract AB The regulation of transcription requires the coordination of numerous activities on DNA, yet it remains poorly understood how transcription factors facilitate these multiple functions. Here we use lattice light-sheet microscopy to integrate single-molecule and high-speed 4D imaging in developing Drosophila embryos to study the nuclear organization and interactions of the key patterning factors Zelda and Bicoid. In contrast to previous studies suggesting stable, cooperative binding, we show that both factors interact with DNA with surprisingly high off-rates. We find that both factors form dynamic subnuclear hubs, and that Bicoid binding is enriched within Zelda hubs. Remarkably, these hubs are both short lived and interact only transiently with sites of active Bicoid dependent transcription. Based on our observations we hypothesize that, beyond simply forming bridges between DNA and the transcription machinery, transcription factors can organize other proteins into hubs that transiently drive multiple activities at their gene targets.