McKinnon Lucas J, Fukushima Jeremy, Endow Joshua K, Inoue Kentaro, Theg Steven M
Department of Plant Sciences, University of California, Davis, California 95616.
Department of Plant Biology, University of California, Davis, California 95616.
Plant Cell. 2020 May;32(5):1589-1609. doi: 10.1105/tpc.19.00797. Epub 2020 Mar 13.
Protein folding is a complex cellular process often assisted by chaperones, but it can also be facilitated by interactions with lipids. Disulfide bond formation is a common mechanism to stabilize a protein. This can help maintain functionality amid changes in the biochemical milieu, including those relating to energy-transducing membranes. Plastidic Type I Signal Peptidase 1 (Plsp1) is an integral thylakoid membrane signal peptidase that requires an intramolecular disulfide bond for in vitro activity. We have investigated the interplay between disulfide bond formation, lipids, and pH in the folding and activity of Plsp1. By combining biochemical approaches with a genetic complementation assay using plants, we provide evidence that interactions with lipids in the thylakoid membrane have reconstitutive chaperoning activity toward Plsp1. Further, the disulfide bridge appears to prevent an inhibitory conformational change resulting from proton motive force-mimicking pH conditions. Broader implications related to the folding of proteins in energy-transducing membranes are discussed.
蛋白质折叠是一个复杂的细胞过程，通常由伴侣蛋白协助，但与脂质的相互作用也可以促进其折叠。二硫键形成是稳定蛋白质的常见机制。这有助于在生化环境变化（包括与能量转换膜相关的变化）中维持蛋白质的功能。质体I型信号肽酶1（Plsp1）是一种整合在类囊体膜上的信号肽酶，其体外活性需要分子内二硫键。我们研究了二硫键形成、脂质和pH值在Plsp1折叠和活性中的相互作用。通过将生化方法与使用植物的遗传互补试验相结合，我们提供了证据表明类囊体膜中与脂质的相互作用对Plsp1具有重组伴侣活性。此外，二硫桥似乎可以防止由模拟质子动力的pH条件导致的抑制性构象变化。本文还讨论了与能量转换膜中蛋白质折叠相关的更广泛意义。
