The ATPases of cohesin interface with regulators to modulate cohesin-mediated DNA tethering.

Gamze Çamdere,Vincent Guacci,Jeremiah Stricklin,Douglas Koshland

doi:10.7554/elife.11315

Abstract

Cohesin tethers together regions of DNA, thereby mediating higher order chromatin organization that is critical for sister chromatid cohesion, DNA repair and transcriptional regulation. Cohesin contains a heterodimeric ATP-binding Cassette (ABC) ATPase comprised of Smc1 and Smc3 ATPase active sites. These ATPases are required for cohesin to bind DNA. Cohesin's DNA binding activity is also promoted by the Eco1 acetyltransferase and inhibited by Wpl1. Recently we showed that after cohesin stably binds DNA, a second step is required for DNA tethering. This second step is also controlled by Eco1 acetylation. Here, we use genetic and biochemical analyses to show that this second DNA tethering step is regulated by cohesin ATPase. Furthermore, our results also suggest that Eco1 promotes cohesion by modulating the ATPase cycle of DNA-bound cohesin in a state that is permissive for DNA tethering and refractory to Wpl1 inhibition.

Highlights

Multi-subunit protein complexes called Structural Maintenance of Chromosomes (SMC) mediate most aspects of higher-order chromosome organization (Hirano, 2006)
We provide evidence suggesting that the Smc1 ATPase active site is involved only in regulating DNA binding, whereas the Smc3 ATPase active site functions in DNA tethering as well as DNA binding
Cohesin binding to chromosomes in vivo is enriched at centromeres and at cohesion-associated regions (CARs) along the chromosome arms (Laloraya et al, 2000; Onn et al, 2008), and is highly salt resistant (Ciosk et al, 2000)

Summary

Introduction

Multi-subunit protein complexes called Structural Maintenance of Chromosomes (SMC) mediate most aspects of higher-order chromosome organization (Hirano, 2006). Cohesin is involved in mitotic condensation, meiotic chromosome condensation and structure, post-replicative DNA repair, and transcriptional regulation (Onn et al, 2008). Cohesin performs these different functions by tethering together two regions of DNA, either within a single DNA molecule (condensation and regulation of gene expression) or between two DNA molecules (sister chromatid cohesion and DNA repair). The Smc ATPase active site contains the Smc3-encoded Walker A and Walker B motifs, and Smc1encoded D-loop and signature motifs (Arumugam et al, 2006; Haering et al, 2004; Hopfner et al, 2000) (Figure 1A inset).

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