Leiden University, Leiden, The Netherlands.
Protein Sci. 2022 Jun;31(6):e4328. doi: 10.1002/pro.4328.
Evolution minimizes the number of highly conserved amino acid residues in proteins to ensure evolutionary robustness and adaptability. The roles of all highly conserved, non-catalytic residues, 11% of all residues, in class A β-lactamase were analyzed by studying the effect of 146 mutations on in cell and in vitro activity, folding, structure, and stability. Residues around the catalytic residues (second shell) contribute to fine-tuning of the active site structure. Mutations affect the structure over the entire active site and can result in stable but inactive protein. Conserved residues farther away (third shell) ensure a favorable balance of folding versus aggregation or stabilize the folded form over the unfolded state. Once folded, the mutant enzymes are stable and active and show only localized structural effects. These residues are found in clusters, stapling secondary structure elements. The results give an integral picture of the different roles of essential residues in enzymes.
进化使蛋白质中高度保守的氨基酸残基数量最小化，以确保进化的稳健性和适应性。通过研究 146 种突变对细胞内和体外活性、折叠、结构和稳定性的影响，分析了所有高度保守的、非催化的残基（占所有残基的 11%）在 A 类β-内酰胺酶中的作用。催化残基（第二壳层）周围的残基有助于微调活性位点结构。突变会影响整个活性位点的结构，导致稳定但无活性的蛋白质。更远的保守残基（第三壳层）确保了折叠与聚集之间有利的平衡，或者使折叠形式相对于未折叠状态稳定。一旦折叠，突变酶是稳定和有活性的，只表现出局部的结构效应。这些残基存在于簇中，固定二级结构元件。这些结果给出了酶中必需残基不同作用的整体图像。
