Lee Kwan Yin, Ranger Mathieu, Meneghini Marc D
Department of Molecular Genetics, University of Toronto, ON, M5S 1A8, Canada.
Department of Molecular Genetics, University of Toronto, ON, M5S 1A8, Canada
G3 (Bethesda). 2018 Nov 6;8(11):3411-3420. doi: 10.1534/g3.118.200589.
Much of euchromatin regulation occurs through reversible methylation of histone H3 lysine-4 and lysine-36 (H3K4me and H3K36me). Using the budding yeast , we previously found that levels of H3K4me modulated temperature sensitive alleles of the transcriptional elongation complex Spt6-Spn1 through an unknown H3K4me effector pathway. Here we identify the Rpd3S histone deacetylase complex as the H3K4me effector underlying these Spt6-Spn1 genetic interactions. Exploiting these Spt6-Spn1 genetic interactions, we show that H3K4me and H3K36me collaboratively impact Rpd3S function in an opposing manner. H3K36me is deposited by the histone methyltransferase Set2 and is known to promote Rpd3S function at RNA PolII transcribed open reading frames. Using genetic epistasis experiments, we find that mutations perturbing the Set2-H3K36me-Rpd3S pathway suppress the growth defects caused by temperature sensitive alleles of and , illuminating that this pathway antagonizes Spt6-Spn1 Using these sensitive genetic assays, we also identify a role for H3K4me in antagonizing Rpd3S that functions through the Rpd3S subunit Rco1, which is known to bind H3 N-terminal tails in a manner that is prevented by H3K4me. Further genetic experiments reveal that the H3K4 and H3K36 demethylases and mediate this combinatorial control of Rpd3S. Finally, our studies also show that the Rpd3L complex, which acts at promoter-proximal regions of PolII transcribed genes, counters Rpd3S for genetic modulation of Spt6-Spn1, and that these two Rpd3 complexes balance the activities of each other. Our findings present the first evidence that H3K4me and H3K36me act combinatorially to control Rpd3S.
常染色质的调控大多通过组蛋白H3赖氨酸4和赖氨酸36（H3K4me和H3K36me）的可逆甲基化来实现。利用芽殖酵母，我们之前发现H3K4me的水平通过一条未知的H3K4me效应途径调节转录延伸复合物Spt6 - Spn1的温度敏感等位基因。在此，我们确定Rpd3S组蛋白去乙酰化酶复合物是这些Spt6 - Spn1基因相互作用背后的H3K4me效应物。利用这些Spt6 - Spn1基因相互作用，我们表明H3K4me和H3K36me以相反的方式协同影响Rpd3S的功能。H3K36me由组蛋白甲基转移酶Set2沉积，已知其在RNA PolII转录的开放阅读框处促进Rpd3S的功能。通过遗传上位性实验，我们发现干扰Set2 - H3K36me - Rpd3S途径的突变可抑制由 和 的温度敏感等位基因引起的生长缺陷，这表明该途径拮抗Spt6 - Spn1。利用这些敏感的遗传检测方法，我们还确定了H3K4me在通过Rpd3S亚基Rco1拮抗Rpd3S中的作用，已知Rco1以一种被H3K4me阻止的方式结合H3的N末端尾巴。进一步的遗传实验表明，H3K4和H3K36去甲基酶 和 介导了对Rpd3S的这种组合控制。最后，我们的研究还表明，作用于PolII转录基因启动子近端区域的Rpd3L复合物，在对Spt6 - Spn1进行遗传调控时与Rpd3S相互对抗，并且这两种Rpd3复合物相互平衡彼此的活性。我们的研究结果首次证明H3K4me和H3K36me共同作用来控制Rpd3S。
