Reconstitution of surface lipoprotein translocation through the Slam translocon.
Reconstitution of surface lipoprotein translocation through the Slam translocon.
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DOI：
10.7554/elife.72822
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发表时间：
2022-04-27
期刊：
影响因子：
7.7
通讯作者：
Moraes, Trevor F.
中科院分区：
文献类型：
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作者：
Huynh, Minh Sang;Hooda, Yogesh;Li, Yuzi Raina;Jagielnicki, Maciej;Lai, Christine Chieh-Lin;Moraes, Trevor F.
表面脂蛋白（SLP）在许多革兰氏阴性菌中外周附着于外膜的外小叶，在宿主的营养获取和免疫逃避中起重要作用。虽然参与SLP在内膜中的合成和递送的因素被很好地表征，但是SLP向表面移动所需的分子机制仍然没有完全阐明。在这项研究中，我们研究了通过Slam 1依赖性途径的SLP TbpB易位。使用纯化的成分，我们开发了一种体外易位试验，其中未折叠的TbpB通过含有Slam 1的脂蛋白体转运，确认Slam 1作为外膜易位子。在寻找增加易位效率的因素时，我们发现了大肠杆菌周质中的周质伴侣Skp与TbpB相互作用。发现Skp的存在增加了重构易位测定中TbpB的易位效率。在脑膜炎奈瑟氏球菌中敲除Skp揭示了Skp对于TbpB功能性易位至细菌表面是必不可少的。总而言之，我们提出了一种表面定位脂蛋白的途径，其中Skp充当SLAM介导的TbpB跨外膜转运的保持酶。
Surface lipoproteins (SLPs) are peripherally attached to the outer leaflet of the outer membrane in many Gram-negative bacteria, playing significant roles in nutrient acquisition and immune evasion in the host. While the factors that are involved in the synthesis and delivery of SLPs in the inner membrane are well characterized, the molecular machinery required for the movement of SLPs to the surface are still not fully elucidated. In this study, we investigated the translocation of a SLP TbpB through a Slam1-dependent pathway. Using purified components, we developed an in vitro translocation assay where unfolded TbpB is transported through Slam1-containing proteoliposomes, confirming Slam1 as an outer membrane translocon. While looking to identify factors to increase translocation efficiency, we discovered the periplasmic chaperone Skp interacted with TbpB in the periplasm of Escherichia coli. The presence of Skp was found to increase the translocation efficiency of TbpB in the reconstituted translocation assays. A knockout of Skp in Neisseria meningitidis revealed that Skp is essential for functional translocation of TbpB to the bacterial surface. Taken together, we propose a pathway for surface destined lipoproteins, where Skp acts as a holdase for Slam-mediated TbpB translocation across the outer membrane.