Eco1 Is a Novel Acetyltransferase that Can Acetylate Proteins Involved in Cohesion

Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030, Vienna, Austria.
Current Biology (Impact Factor: 9.57). 03/2002; 12(4):323-8. DOI: 10.1016/S0960-9822(02)00681-4
Source: PubMed


Cohesion between sister chromatids is established during S phase and maintained through G2 phase until it is resolved in anaphase (for review, see [1-3]). In Saccharomyces cerevisiae, a complex consisting of Scc1, Smc1, Smc3, and Scc3 proteins, called "cohesin," mediates the connection between sister chromatids. The evolutionary conserved yeast protein Eco1 is required for establishment of sister chromatid cohesion during S phase but not for its further maintenance during G2 or M phases or for loading the cohesin complex onto DNA. We address the molecular functions of Eco1 with sensitive sequence analytic techniques, including hidden Markov model domain fragment searches. We found a two-domain architecture with an N-terminal C2H2 Zn finger-like domain and an approximately 150 residue C-terminal domain with an apparent acetyl coenzyme A binding motif ( Biochemical tests confirm that Eco1 has the acetyltransferase activity in vitro. In vitro Eco1 acetylates itself and components of the cohesin complex but not histones. Thus, the establishment of cohesion between sister chromatids appears to be regulated, directly or indirectly, by a specific acetyltransferase.

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    • "Cohesin is deposited across chromosomes by the SCC2/4 cohesin loader. Cohesin becomes cohesive during DNA replication through acetylation by Eco1 (Ivanov et al. 2002; Rolef Ben-Shahar et al. 2008; Unal et al. 2008; Zhang et al. 2008; Heidinger-Pauli et al. 2009). Activation of cohesin is linked to DNA replication via proteins like Ctf4 and Ctf8 (Lengronne et al. 2006; Skibbens 2009) that facilitate the acetylation of cohesin. "
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    ABSTRACT: Gain or loss of chromosomes resulting in aneuploidy can be important factors in cancer and adaptive evolution. Although chromosome gain is a frequent event in eukaryotes, there is limited information on its genetic control. Here we measured the rates of chromosome gain in wild type yeast and sister chromatid cohesion (SCC) compromised strains. SCC tethers the newly replicated chromatids until anaphase via the cohesin complex. Chromosome gain was measured by selecting and characterizing copper resistant colonies that emerged due to increased copies of the metallothionein gene CUP1. Although all defective SCC diploid strains exhibited increased rates of chromosome gain, there were 15-fold differences between them. Of all mutants examined, a hypomorphic mutation at the cohesin complex caused the highest rate of chromosome gain while disruption of WPL1, an important regulator of SCC and chromosome condensation, resulted in the smallest increase in chromosome gain. In addition to defects in SCC, yeast cell type contributed significantly to chromosome gain, with the greatest rates observed for homozygous mating type diploids, followed by heterozygous mating type and smallest in haploids. In fact, wpl1 deficient haploids did not show any difference in chromosome gain rates compared to WT haploids. Genomic analysis of copper-resistant colonies revealed that the "driver" chromosome for which selection was applied could be amplified to over 5 copies per diploid cell. In addition, an increase in the expected "driver" chromosome was often accompanied by a gain of a small number of other chromosomes. We suggest that while chromosome gain due to SCC malfunction can have negative effects through gene imbalance, it could also facilitate opportunities for adaptive changes. In multicellular organisms, both factors could lead to somatic diseases including cancer.
    Genetics 12/2013; 196(2). DOI:10.1534/genetics.113.159202 · 5.96 Impact Factor
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    • "We realized that reduced Smc3 acetylation in chl1 mutant cells can be explained by at least one of two models: that Chl1 promotes Eco1 acetyltransferase activity or that Chl1 promotes cohesin binding to DNA which in turn becomes a suitable substrate for Eco1. To test the first of these possibilities, we exploited the fact that auto-acetylation is readily detected in Eco1/ESCO proteins [27,29,30,69]. Logarithmically growing wild type and chl1 mutant cells expressing Eco1-18MYC as the sole source of Eco1 were lysed and the resulting extracts incubated with anti-MYC-coupled beads. "
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    ABSTRACT: The conserved family of cohesin proteins that mediate sister chromatid cohesion requires Scc2, Scc4 for chromatin-association and Eco1/Ctf7 for conversion to a tethering competent state. A popular model, based on the notion that cohesins form huge ring-like structures, is that Scc2, Scc4 function is essential only during G1 such that sister chromatid cohesion results simply from DNA replisome passage through pre-loaded cohesin rings. In such a scenario, cohesin deposition during G1 is temporally uncoupled from Eco1-dependent establishment reactions that occur during S-phase. Chl1 DNA helicase (homolog of human ChlR1/DDX11 and BACH1/BRIP1/FANCJ helicases implicated in Fanconi anemia, breast and ovarian cancer and Warsaw Breakage Syndrome) plays a critical role in sister chromatid cohesion, however, the mechanism through which Chl1 promotes cohesion remains poorly understood. Here, we report that Chl1 promotes Scc2 loading unto DNA such that both Scc2 and cohesin enrichment to chromatin are defective in chl1 mutant cells. The results further show that both Chl1 expression and chromatin-recruitment are tightly regulated through the cell cycle, peaking during S-phase. Importantly, kinetic ChIP studies reveals that Chl1 is required for Scc2 chromatin-association specifically during S-phase, but not during G1. Despite normal chromatin enrichment of both Scc2 and cohesin during G1, chl1 mutant cells exhibit severe chromosome segregation and cohesion defects - revealing that G1-loaded cohesins is insufficient to promote cohesion. Based on these findings, we propose a new model wherein S-phase cohesin loading occurs during DNA replication and in concert with both cohesion establishment and chromatin assembly reactions - challenging the notion that DNA replication fork navigates through or around pre-loaded cohesin rings.
    PLoS ONE 09/2013; 8(9):e75435. DOI:10.1371/journal.pone.0075435 · 3.23 Impact Factor
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    • "Crucially, formation of cohesion between sister chromatids stable enough to facilitate chromosome segregation depends on marking a subset of cohesin complexes in a manner that causes them to be refractory to releasing activity. This is achieved by the modification during S phase of K112 and K113 by the Eco1 acetyl transferase (Ivanov et al, 2002; Ben-Shahar et al, 2008; Unal et al, 2008; Rowland et al, 2009), which in animal cells recruits a protein called sororin that alters the association between Wapl and Pds5 (Nishiyama et al, 2010). If separase releases cohesin from chromatin by enabling DNAs to escape from rings cleaved open by kleisin cleavage, then non-proteolytic release may achieve the same goal by dissociating transiently one of the tripartite ring's three intersubunit interfaces. "
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    ABSTRACT: Cohesin’s Smc1, Smc3, and kleisin subunits create a tripartite ring within which sister DNAs are entrapped. Evidence suggests that DNA enters through a gate created by transient dissociation of the Smc1/3 interface. Release at the onset of anaphase is triggered by proteolytic cleavage of kleisin. Less well understood is the mechanism of release at other stages of the cell cycle, in particular during prophase when most cohesin dissociates from chromosome arms in a process dependent on the regulatory subunit Wapl. We show here that Wapl-dependent release from salivary gland polytene chromosomes during interphase and from neuroblast chromosome arms during prophase is blocked by translational fusion of Smc3’s C-terminus to kleisin’s N-terminus. Our findings imply that proteolysis-independent release of cohesin from chromatin is mediated by Wapl-dependent escape of DNAs through a gate created by transient dissociation of the Smc3/kleisin interface. Thus, cohesin’s DNA entry and exit gates are distinct.
    The EMBO Journal 01/2013; 32(5). DOI:10.1038/emboj.2012.346 · 10.43 Impact Factor
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