The chromatin assembly factor subunit FASCIATA1 is involved in homologous recombination in plants
The chromatin assembly factor subunit FASCIATA1 is involved in homologous recombination in plants
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DOI：
10.1105/tpc.106.045088
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发表时间：
2006-10-01
期刊：
影响因子：
11.6
通讯作者：
Reiss, Bernd
中科院分区：
文献类型：
--
作者：
Kirik, Angela;Pecinka, Ales;Reiss, Bernd
在循环真核细胞中的DNA复制需要在核小体从亲代到两个子DNA链重新分配后重建染色质。染色质组装因子1 （caf1）是由3个亚基（p150/ p60/ p48）组成的异三聚体复合体，是参与S期染色质重构的复制偶联组装因子之一。CAF- 1是体外人类细胞和拟南芥中核小体组装到新复制的染色质上所必需的，酵母（Saccharomycescerevisiae）中的缺陷影响dna的修复过程，主要是那些涉及基因组稳定性的过程。然而，在高等真核生物中，ca2 - 1突变体的体内染色质缺陷尚不清楚。在这里，我们发现fasciata1- 4 （fas1- 4）是CAF- 1 p150亚基缺陷的拟南芥fas1突变体的一个新等位基因，具有严重的发育表型，异染色质含量减少，并且铁质的开放构象。最重要的是，同源重组（HR），一个参与维持基因组稳定性的过程，在fas1- 4中急剧增加，正如染色体内HR的96倍刺激所表明的那样。结合突变体中染色质的开放构象和hrgenes接近正常的表达水平，这一结果表明染色质是限制hrin植物的主要因素。
DNA replication in cycling eukaryotic cells necessitates the reestablishment of chromatin after nucleosome redistribution from the parental to the two daughter DNA strands. Chromatin assembly factor 1 ( CAF-1), a heterotrimeric complex consisting of three subunits ( p150/ p60/ p48), is one of the replication- coupled assembly factors involved in the reconstitution of S- phase chromatin. CAF- 1 is required in vitro for nucleosome assembly onto newly replicated chromatin in human cells and Arabidopsis thaliana, anddefects in yeast ( Saccharomycescerevisiae) affectDNAdamagerepair processes, predominantly thoseinvolvedin genome stability. However, in vivo chromatin defects of caf- 1 mutants in higher eukaryotes are poorly characterized. Here, we show that fasciata1- 4 ( fas1- 4), a new allele of the Arabidopsis fas1 mutant defective in the p150 subunit of CAF- 1, has a severe developmentalphenotype, reduced heterochromatin content, andamoreopenconformation ofeuchromatin. Mostimportantly, homologous recombination ( HR), a process involved in maintaining genome stability, is increased dramatically in fas1- 4, as indicated by a 96- fold stimulation of intrachromosomal HR. Together with the open conformation of chromatin and the nearly normal expression levels ofHRgenes in the mutant, this result suggests that chromatin is a major factor restrictingHRin plants.