研究人员表示，β桶状外膜蛋白（β-OMP）在线粒体、叶绿体和革兰氏阴性菌中发挥着重要作用。进化保守的复合体，如线粒体分拣和组装机器（SAM）介导了β-OMP的组装。
研究人员报道了SAM介导的外膜转运酶（TOM）核心复合物的组装。完全折叠的Tom40和SAM-Tom40/Tom5/Tom6复合物的冷冻电镜结构在~3埃的分辨率下显示，Sam37主要通过静电相互作用稳定成熟的Tom40，从而促进随后的TOM组装。这些结果支持了β桶切换模型，并为β桶复合体的组装和释放提供了结构上的见解。
附：英文原文
Title: Structural insight into the SAM-mediated assembly of the mitochondrial TOM core complex
Author: Qiang Wang, Zeyuan Guan, Liangbo Qi, Jinjin Zhuang, Chen Wang, Sixing Hong, Ling Yan, Yan Wu, Xiaoqian Cao, Jianbo Cao, Junjie Yan, Tingting Zou, Zhu Liu, Delin Zhang, Chuangye Yan, Ping Yin
Issue&Volume: 2021-09-17
Abstract: β barrel outer membrane proteins (β-OMPs) play vital roles in mitochondria, chloroplasts, and Gram-negative bacteria. Evolutionarily conserved complexes such as the mitochondrial sorting and assembly machinery (SAM) mediate the assembly of β-OMPs. We investigated the SAM-mediated assembly of the translocase of the outer membrane (TOM) core complex. Cryo–electron microscopy structures of SAM–fully folded Tom40 and the SAM-Tom40/Tom5/Tom6 complexes at ~3-angstrom resolution reveal that Sam37 stabilizes the mature Tom40 mainly through electrostatic interactions, thus facilitating subsequent TOM assembly. These results support the β barrel switching model and provide structural insights into the assembly and release of β barrel complexes.
DOI: abh0704
Source: https://www.science.org/doi/10.1126/science.abh0704