The conserved histone chaperone Spt6 facilitates DNA replication and mediates genome instability [BrdU-IP-seq]

Histone chaperones are an important class of factors that regulate chromatin accessibility for DNA-templated processes. Spt6 is a conserved histone chaperone and key regulator of transcription and chromatin structure. However, its functions outside of these roles have been little explored. In this work, we demonstrate a role for Spt6 in DNA replication and more broadly as a regulator of genome stability. Spt6 binds the replication machinery and mutations or loss of Spt6 impair DNA replication in vivo. Additionally, spt6 mutants are sensitive to DNA replication stress inducing agents, with increased sensitivity when combined with loss of DNA replication associated factors. Furthermore, spt6 mutants have elevated levels of DNA double strand breaks and are hyper-recombinogenic. R-loops do not appear to be elevated in spt6 mutants. In total, we identify Spt6 as a regulator of genome stability, at least in part through a role for Spt6 in DNA replication.组蛋白伴侣（histone chaperones）是一类调控以DNA为模板的生物学过程中染色质可及性的重要因子。Spt6是一种保守的组蛋白伴侣，同时也是转录与染色质结构的关键调控因子。然而，其在上述功能之外的作用却鲜有研究。本研究证实，Spt6在DNA复制中发挥作用，且可作为基因组稳定性的广谱调控因子。Spt6可结合复制机器，体内Spt6的突变或缺失会损伤DNA复制过程。此外，spt6突变体对DNA复制应激诱导剂敏感，且当与DNA复制相关因子的缺失联合存在时，其敏感性进一步升高。进一步研究发现，spt6突变体的DNA双链断裂水平升高，且重组活性异常增强。R环（R-loops）在spt6突变体中未见水平升高现象。综上，本研究确定Spt6是基因组稳定性的调控因子，其功能至少部分通过其在DNA复制中的作用实现。