Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
Int J Mol Sci. 2024 Sep 20;25(18):10101. doi: 10.3390/ijms251810101.
Selenocysteine (Sec) is an essential amino acid that distinguishes itself from cysteine by a selenium atom in place of a sulfur atom. This single change imparts distinct chemical properties to Sec which are crucial for selenoprotein (Sec-containing protein) function. These properties include a lower p, enhanced nucleophilicity, and reversible oxidation. However, studying Sec incorporation in proteins is a complex process. While we find Sec in all domains of life, each domain has distinct translation mechanisms. These mechanisms are unique to canonical translation and are composed of Sec-specific enzymes and an mRNA hairpin to drive recoding of the UGA stop codon with Sec. In this review, we highlight the obstacles that arise when investigating Sec insertion, and the role that Sec has in proteins. We discuss the strategic methods implemented in this field to address these challenges. Though the Sec translation system is complex, a remarkable amount of information has been obtained and specialized tools have been developed. Continued studies in this area will provide a deeper understanding on the role of Sec in the context of proteins, and the necessity that we have for maintaining this complex translation machinery to make selenoproteins.
硒代半胱氨酸（Sec）是一种必需氨基酸，与半胱氨酸的区别在于硒原子取代了硫原子。这一单一变化赋予了 Sec 独特的化学性质，对硒蛋白（含 Sec 的蛋白质）的功能至关重要。这些特性包括较低的 pKa 值、增强的亲核性和可逆氧化。然而，研究 Sec 在蛋白质中的掺入是一个复杂的过程。虽然我们在所有生命领域都发现了 Sec，但每个领域都有独特的翻译机制。这些机制是典型翻译所特有的，由 Sec 特异性酶和 mRNA 发夹组成，以驱动 Sec 对 UGA 终止密码子的重编码。在这篇综述中，我们强调了在研究 Sec 插入时出现的障碍，以及 Sec 在蛋白质中的作用。我们讨论了该领域中为解决这些挑战而采用的策略方法。尽管 Sec 翻译系统很复杂，但已经获得了大量信息，并开发了专门的工具。在该领域的持续研究将提供对 Sec 在蛋白质背景下的作用以及我们维持这种复杂翻译机制以产生硒蛋白的必要性的更深入理解。
