Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, 93106, USA.
Department of Molecular Biology & Biochemistry, University of California, Irvine, Irvine, 92697, USA.
Nat Commun. 2024 Oct 11;15(1):8804. doi: 10.1038/s41467-024-53075-x.
Advanced glycation end-products (AGE) are a pervasive form of protein damage implicated in the pathogenesis of neurodegenerative disease, atherosclerosis and diabetes mellitus. Glycation is typically mediated by reactive dicarbonyl compounds that accumulate in all cells as toxic byproducts of glucose metabolism. Here, we show that AGE crosslinking is harnessed to activate an antibacterial phospholipase effector protein deployed by the type VI secretion system of Enterobacter cloacae. Endogenous methylglyoxal reacts with a specific arginine-lysine pair to tether the N- and C-terminal α-helices of the phospholipase domain. Substitutions at these positions abrogate both crosslinking and toxic phospholipase activity, but in vitro enzyme function can be restored with an engineered disulfide that covalently links the N- and C-termini. Thus, AGE crosslinking serves as a bona fide post-translation modification to stabilize phospholipase structure. Given the ubiquity of methylglyoxal in prokaryotic and eukaryotic cells, these findings suggest that glycation may be exploited more generally to stabilize other proteins. This alternative strategy to fortify tertiary structure could be particularly advantageous in the cytoplasm, where redox potentials preclude disulfide bond formation.
糖基化终产物（AGE）是一种普遍存在的蛋白质损伤形式，与神经退行性疾病、动脉粥样硬化和糖尿病的发病机制有关。糖基化通常由反应性二羰基化合物介导，这些化合物作为葡萄糖代谢的毒性副产物在所有细胞中积累。在这里，我们表明 AGE 交联被利用来激活肠杆菌科的 VI 型分泌系统部署的一种抗菌磷脂酶效应蛋白。内源性甲基乙二醛与特定的精氨酸-赖氨酸对反应，将磷脂酶结构域的 N-和 C-末端α螺旋连接起来。这些位置的取代会破坏交联和有毒的磷脂酶活性，但可以通过工程化的二硫键恢复体外酶功能，该二硫键共价连接 N-和 C-末端。因此，AGE 交联是稳定磷脂酶结构的真正的翻译后修饰。鉴于甲基乙二醛在原核和真核细胞中的普遍性，这些发现表明糖基化可能更普遍地被用来稳定其他蛋白质。这种强化三级结构的替代策略在细胞质中可能特别有利，因为氧化还原电势排除了二硫键的形成。
