SMC complexes can traverse physical roadblocks bigger than their ring size

Ring-shaped structural maintenance of chromosomes (SMC) complexes like condensin and cohesin extrude loops of DNA. It remains, however, unclear how they can extrude DNA loops in chromatin that is bound with proteins. Here, we use in vitro single-molecule visualization to show that nucleosomes, RNA polymerase, and dCas9 pose virtually no...

Distinct Roles for Condensin's Two ATPase Sites in Chromosome Condensation

Condensin is a conserved SMC complex that uses its ATPase machinery to structure genomes, but how it does so is largely unknown. We show that condensin's ATPase has a dual role in chromosome condensation. Mutation of one ATPase site impairs condensation, while mutating the second site results in hyperactive condensin that compacts DNA faster...

Single-molecule approaches to unravel the mechanism of SMC proteins

Every cell deals with the challenge of organising its DNA. First, the DNA needs to be compacted in size by several orders of magnitude. For example, in each human cell, 2 meters of DNA need to fit inside a micron-sized cell nucleus. Second, the DNA needs to stay accessible for cellular processes such as transcription and replication. To achieve...

Single-molecule studies of the twisted, knotted, and broken genome

This thesis describes a series of single-molecule experiments aimed at understanding the physical properties of DNA itself and the proteins that interact with it. We developed and applied sensitive techniques that allowed us to directly probe the conformation and interactions of individual DNA molecules and proteins. Magnetic and optical...