Biology subjects

Lavis, L.

Publications and source records attributed to Lavis, L..

2 recordsLinked to original sources

bioRxiv2017

Dynamic and Selective Low-Complexity Domain Interactions Revealed by Live-Cell Single-Molecule Imaging

Many eukaryotic transcription factors (TFs) contain intrinsically disordered low-complexity domains (LCDs) but how they perform transactivation functions remains unclear. Recent studies report that TF-LCDs can undergo hydrogel formation or liquid-liquid phase separation in vitro. Here, live-cell single-molecule imaging reveals that TF-LCDs form local high concentration interaction hubs at synthetic and endogenous genomic loci. TF-LCD hubs stabilize DNA binding, recruit RNA polymerase II (Pol II) and activate transcription. LCD-LCD interactions within hubs are highly dynamic, display selectivity with binding partners, and are differentially sensitive to disruption by hexanediols. These findings suggest that under physiological conditions, rapid reversible and multivalent LCD-LCD interactions occur between TFs and the Pol II machinery, which underpins a central mechanism for transactivation and plays a key role in gene expression and disease.

biophysics↗

bioRxiv2017

Cohesin Can Remain Associated With Chromosomes During DNA Replication

To ensure disjunction to opposite poles during anaphase, sister chromatids must be held together following DNA replication. This is mediated by cohesin, which is thought to entrap sister DNAs inside a tripartite ring composed of its Smc and kleisin (Scc1) subunits. How such structures are created during S phase is poorly understood, in particular whether they are derived from complexes that had entrapped DNAs prior to replication. To address this, we used selective photobleaching to determine whether cohesin associated with chromatin in G1 persists in situ after replication. We used unlabelled HaloTag ligand following fluorescent labelling to block newly synthesised Halo-tagged Scc1 protein from incorporating fluorescent dye (pulse-chase or pcFRAP). In cells whose cohesin turnover is inactivated by deletion of WAPL, Scc1 remains associated with chromatin throughout S phase. These findings suggest that cohesion might be generated by cohesin that is already bound to unreplicated DNA.

cell biology↗