AbstractThe sirtuins are NAD+‐dependent lysine deacylases, comprising seven isoforms (SIRT1–7) in humans, which are involved in the regulation of a plethora of biological processes, including gene expression and metabolism. The sirtuins share a common hydrolytic mechanism but display preferences for different ϵ‐N‐acyllysine substrates. SIRT7 deacetylates targets in nuclei and nucleoli but remains one of the lesser studied of the seven isoforms, in part due to a lack of chemical tools to specifically probe SIRT7 activity. Here we expressed SIRT7 and, using small‐angle X‐ray scattering, reveal SIRT7 to be a monomeric enzyme with a low degree of globular flexibility in solution. We developed a fluorogenic assay for investigation of the substrate preferences of SIRT7 and to evaluate compounds that modulate its activity. We report several mechanism‐based SIRT7 inhibitors as well as de novo cyclic peptide inhibitors selected from mRNA‐display library screening that exhibit selectivity for SIRT7 over other sirtuin isoforms, stabilize SIRT7 in cells, and cause an increase in the acetylation of H3 K18.
摘要sirtuins是一种依赖于NAD+的赖氨酸脱乙酰酶,在人类中有7种同工酶(SIRT1-7),它们参与了大量生物过程的调控,包括基因表达和新陈代谢。sirtuins具有共同的水解机制,但对ϵ-N-酰基赖氨酸底物有不同的偏好。SIRT7 可使细胞核和核小体中的靶标去乙酰化,但仍是七种同工酶中研究较少的一种,部分原因是缺乏特异性探究 SIRT7 活性的化学工具。在这里,我们表达了 SIRT7,并利用小角 X 射线散射揭示了 SIRT7 是一种单体酶,在溶液中具有较低的球状柔性。我们开发了一种荧光测定法,用于研究 SIRT7 的底物偏好,并评估调节其活性的化合物。我们报告了几种基于机制的 SIRT7 抑制剂以及从 mRNA 显示库筛选出的新环肽抑制剂,它们对 SIRT7 比其他 sirtuin 同工酶具有选择性,能稳定细胞中的 SIRT7,并能增加 H3 K18 的乙酰化。