Gong Minheng, Ye Qiaozhen, Gu Yajie, Chambers Lydia R, Bobkov Andrey A, Arakawa Neal K, Matyszewski Mariusz, Corbett Kevin D
Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla CA 92093.
Department of Chemistry and Biochemistry, University of California San Diego, La Jolla CA 92093.
bioRxiv. 2024 Nov 25:2024.11.21.623966. doi: 10.1101/2024.11.21.623966.
Bacteria possess a variety of operons with homology to eukaryotic ubiquitination pathways that encode predicted E1, E2, E3, deubiquitinase, and ubiquitin-like proteins. Some of these pathways have recently been shown to function in anti-bacteriophage immunity, but the biological functions of others remain unknown. Here, we show that ubiquitin-like proteins in two bacterial operon families show surprising architectural diversity, possessing one to three β-grasp domains preceded by diverse N-terminal domains. We find that a large group of bacterial ubiquitin-like proteins possess three β-grasp domains and form homodimers and helical filaments mediated by conserved Ca ion binding sites. Our findings highlight a distinctive mode of self-assembly for ubiquitin-like proteins, and suggest that Ca-mediated ubiquitin-like protein filament assembly and/or disassembly enables cells to sense and respond to stress conditions that alter intracellular metal ion concentration.
细菌拥有多种与真核生物泛素化途径具有同源性的操纵子，这些操纵子编码预测的E1、E2、E3、去泛素化酶和类泛素蛋白。最近已证明其中一些途径在抗噬菌体免疫中起作用，但其他途径的生物学功能仍不清楚。在这里，我们表明两个细菌操纵子家族中的类泛素蛋白表现出惊人的结构多样性，在不同的N端结构域之前具有一到三个β-抓握结构域。我们发现一大类细菌类泛素蛋白具有三个β-抓握结构域，并形成由保守的钙离子结合位点介导的同型二聚体和螺旋丝。我们的研究结果突出了类泛素蛋白独特的自组装模式，并表明钙介导的类泛素蛋白丝组装和/或拆卸使细胞能够感知并响应改变细胞内金属离子浓度的应激条件。
