Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy; Centro di Ricerca Pediatrica Romeo ed Enrica Invernizzi, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
J Mol Biol. 2019 Nov 8;431(22):4523-4526. doi: 10.1016/j.jmb.2019.08.011. Epub 2019 Aug 29.
Bacterial NADPH-dependent glutamate synthase (GltS) is a complex iron-sulfur flavoprotein that catalyzes the reductive synthesis of two L-Glu molecules from L-Gln and 2-oxo-glutarate. GltS functional unit hosts an α-subunit (αGltS) and a β-subunit (βGltS) that assemble in different αβ oligomers in solution. Here, we present the cryo-electron microscopy structures of Azospirillum brasilense GltS in four different oligomeric states (αβ, αβ, αβ and αβ, in the 3.5- to 4.1-Å resolution range). Our study provides a comprehensive GltS model that details the inter-protomeric assemblies and allows unequivocal location of the FAD cofactor and of two electron transfer [4Fe-4S] clusters within βGltS.
细菌 NADPH 依赖性谷氨酸合酶（GltS）是一种复杂的铁硫黄素蛋白，可催化 L-Gln 和 2-氧代戊二酸两分子还原合成 L-Glu。GltS 功能单元包含一个α 亚基（αGltS）和一个β 亚基（βGltS），它们在溶液中以不同的αβ 寡聚体形式组装。在这里，我们展示了不同聚合状态（3.5-4.1Å 分辨率范围内的αβ、αβ、αβ 和 αβ）的巴西固氮螺菌 GltS 的冷冻电镜结构。我们的研究提供了一个全面的 GltS 模型，详细说明了蛋白间的组装，并能够明确 FAD 辅因子和βGltS 内两个电子转移[4Fe-4S]簇的位置。
