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Structural insights into DNA loop extrusion by SMC protein complexes.

ABSTRACT: Structural Maintenance of Chromosomes (SMC) protein complexes play key roles in the three-dimensional organization of genomes in all kingdoms of life. Recent insights from chromosome contact mapping experiments and single-molecule imaging assays suggest that these complexes achieve distinct cellular functions by extruding large loops of DNA while they move along the chromatin fiber. In this short review, we summarize recent insights into the molecular architecture of these unconventional DNA motor complexes, their interaction with their DNA substrates, and the remarkable dynamic changes they can undergo during their ATPase reaction cycle.

SUBMITTER: Datta S

PROVIDER: S-EPMC7612452 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Structural insights into DNA loop extrusion by SMC protein complexes.

Datta Sumanjit S Lecomte Léa L Haering Christian H CH

Current opinion in structural biology 20200713

Structural Maintenance of Chromosomes (SMC) protein complexes play key roles in the three-dimensional organization of genomes in all kingdoms of life. Recent insights from chromosome contact mapping experiments and single-molecule imaging assays suggest that these complexes achieve distinct cellular functions by extruding large loops of DNA while they move along the chromatin fiber. In this short review, we summarize recent insights into the molecular architecture of these unconventional DNA mot ...[more]

PMID: 32674008

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DNA-segment-capture model for loop extrusion by structural maintenance of chromosome (SMC) protein complexes.

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Testing pseudotopological and nontopological models for SMC-driven DNA loop extrusion against roadblock-traversal experiments.

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DNA-loop extruding SMC complexes can traverse one another in vivo

Project description:Chromosome organization by structural maintenance of chromosomes (SMC) complexes is vital to living organisms. SMC complexes were recently found to be motors that extrude DNA loops. However, it remains unclear what happens when multiple complexes encounter one another in vivo on the same DNA and how interactions help organize an active genome. We created a crash-course track system to study SMC complex encounters in vivo by engineering the Bacillus subtilis chromosome to have defined SMC loading sites. Chromosome conformation capture (Hi-C) analyses of over 20 engineered strains show an amazing variety of never-before-seen chromosome folding patterns. Via 3D polymer simulations and theory, we find that these patterns require SMC complexes to bypass each other in vivo, as recently seen in an in vitro study. We posit that the bypassing activity enables SMC complexes to spatially organize a functional and busy genome.

2021-06-10 | GSE155279 | GEO

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