Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
Electron Microscope Unit, University of Cape Town, Cape Town, South Africa.
EMBO J. 2022 Aug 16;41(16):e110550. doi: 10.15252/embj.2021110550. Epub 2022 Jul 12.
Hypertension (high blood pressure) is a major risk factor for cardiovascular disease, which is the leading cause of death worldwide. The somatic isoform of angiotensin I-converting enzyme (sACE) plays a critical role in blood pressure regulation, and ACE inhibitors are thus widely used to treat hypertension and cardiovascular disease. Our current understanding of sACE structure, dynamics, function, and inhibition has been limited because truncated, minimally glycosylated forms of sACE are typically used for X-ray crystallography and molecular dynamics simulations. Here, we report the first cryo-EM structures of full-length, glycosylated, soluble sACE (sACE ). Both monomeric and dimeric forms of the highly flexible apo enzyme were reconstructed from a single dataset. The N- and C-terminal domains of monomeric sACE were resolved at 3.7 and 4.1 Å, respectively, while the interacting N-terminal domains responsible for dimer formation were resolved at 3.8 Å. Mechanisms are proposed for intradomain hinging, cooperativity, and homodimerization. Furthermore, the observation that both domains were in the open conformation has implications for the design of sACE modulators.
高血压（高血压）是心血管疾病的主要危险因素，是世界范围内死亡的主要原因。血管紧张素 I 转化酶（sACE）的躯体同工酶在血压调节中起着关键作用，因此 ACE 抑制剂被广泛用于治疗高血压和心血管疾病。由于通常用于 X 射线晶体学和分子动力学模拟的是截短的、最小糖基化的 sACE 形式，因此我们对 sACE 的结构、动力学、功能和抑制的理解受到限制。在这里，我们报告了全长、糖基化、可溶性 sACE（sACE）的第一个冷冻电镜结构。从单个数据集重建了高度灵活的 apo 酶的单体和二聚体形式。单体 sACE 的 N-和 C-末端结构域分别解析为 3.7 和 4.1 Å，而负责二聚体形成的相互作用的 N-末端结构域解析为 3.8 Å。提出了用于结构域内铰链、协同作用和同源二聚化的机制。此外，观察到两个结构域都处于开放构象，这对 sACE 调节剂的设计具有重要意义。
