Wu Jiabing, Yang Yue, Wang Jiachen, Wang Youchao, Yin Liufan, An Zengxuan, Du Kangxi, Zhu Yan, Qi Ji, Shen Wen-Hui, Dong Aiwu
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China.
State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China.
New Phytol. 2023 Jul;239(1):189-207. doi: 10.1111/nph.18940. Epub 2023 May 2.
The histone variant H2A.Z plays key functions in transcription and genome stability in all eukaryotes ranging from yeast to human, but the molecular mechanisms by which H2A.Z is incorporated into chromatin remain largely obscure. Here, we characterized the two homologs of yeast Chaperone for H2A.Z-H2B (Chz1) in Arabidopsis thaliana, AtChz1A and AtChz1B. AtChz1A/AtChz1B were verified to bind to H2A.Z-H2B and facilitate nucleosome assembly in vitro. Simultaneous knockdown of AtChz1A and AtChz1B, which exhibit redundant functions, led to a genome-wide reduction in H2A.Z and phenotypes similar to those of the H2A.Z-deficient mutant hta9-1hta11-2, including early flowering and abnormal flower morphologies. Interestingly, AtChz1A was found to physically interact with ACTIN-RELATED PROTEIN 6 (ARP6), an evolutionarily conserved subunit of the SWR1 chromatin-remodeling complex. Genetic interaction analyses showed that atchz1a-1atchz1b-1 was hypostatic to arp6-1. Consistently, genome-wide profiling analyses revealed partially overlapping genes and fewer misregulated genes and H2A.Z-reduced chromatin regions in atchz1a-1atchz1b-1 compared with arp6-1. Together, our results demonstrate that AtChz1A and AtChz1B act as histone chaperones to assist the deposition of H2A.Z into chromatin via interacting with SWR1, thereby playing critical roles in the transcription of genes involved in flowering and many other processes.
组蛋白变体H2A.Z在从酵母到人类的所有真核生物的转录和基因组稳定性中发挥关键作用，但H2A.Z整合到染色质中的分子机制仍 largely obscure。在这里，我们对拟南芥中H2A.Z-H2B伴侣蛋白（Chz1）的两个同源物AtChz1A和AtChz1B进行了表征。AtChz1A/AtChz1B被证实可与H2A.Z-H2B结合并在体外促进核小体组装。AtChz1A和AtChz1B具有冗余功能，同时敲低它们会导致全基因组范围内H2A.Z的减少以及与H2A.Z缺陷突变体hta9-1hta11-2相似的表型，包括早花和异常的花形态。有趣的是，发现AtChz1A与肌动蛋白相关蛋白6（ARP6）发生物理相互作用，ARP6是SWR1染色质重塑复合物中一个进化保守的亚基。遗传相互作用分析表明atchz1a-1atchz1b-1对arp6-1是下位的。一致地，全基因组分析揭示了atchz1a-1atchz1b-1与arp6-1相比，部分重叠的基因、较少的失调基因以及H2A.Z减少的染色质区域。总之，我们的结果表明AtChz1A和AtChz1B作为组蛋白伴侣蛋白，通过与SWR1相互作用协助H2A.Z沉积到染色质中，从而在参与开花和许多其他过程的基因转录中发挥关键作用。
