{"title":"Visualizing the Domino-Like Prepore-to-Pore Transition of Streptolysin O by High-Speed AFM.","authors":"Hirotaka Ariyama","doi":"10.1007/s00232-022-00261-x","DOIUrl":null,"url":null,"abstract":"<p><p>Pore-forming proteins (PFPs) are produced by various organisms, including pathogenic bacteria, and form pores within the target cell membrane. Streptolysin O (SLO) is a PFP produced by Streptococcus pyogenes and forms high-order oligomers on the membrane surface. In this prepore state, multiple α-helices in domain 3 of each subunit exist as unfolded structures and transiently interact with each other. They subsequently transition into transmembrane β-hairpins (TMHs) and form pores with diameters of 20-30 nm. However, in this pore formation process, the trigger of the transition in a subunit and collaboration between subunits remains elusive. Here, I observed the dynamic pore formation process using high-speed atomic force microscopy. During the oligomer transition process, each subunit was sequentially inserted into the membrane, propagating along the oligomer in a domino-like fashion (chain reaction). This process also occurred on hybrid oligomers containing wildtype and mutant subunits, which cannot insert into the membrane because of an introduced disulfide bond. Furthermore, propagation still occurred when an excessive force was added to hybrid oligomers in the prepore state. Based on the observed chain reactions, I estimate the free energies and forces that trigger the transition in a subunit. Furthermore, I hypothesize that the collaboration between subunits is related to the structure of their TMH regions and interactions between TMH-TMH and TMH-lipid molecules.</p>","PeriodicalId":50129,"journal":{"name":"Journal of Membrane Biology","volume":"256 1","pages":"91-103"},"PeriodicalIF":2.3000,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9884259/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Membrane Biology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s00232-022-00261-x","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Pore-forming proteins (PFPs) are produced by various organisms, including pathogenic bacteria, and form pores within the target cell membrane. Streptolysin O (SLO) is a PFP produced by Streptococcus pyogenes and forms high-order oligomers on the membrane surface. In this prepore state, multiple α-helices in domain 3 of each subunit exist as unfolded structures and transiently interact with each other. They subsequently transition into transmembrane β-hairpins (TMHs) and form pores with diameters of 20-30 nm. However, in this pore formation process, the trigger of the transition in a subunit and collaboration between subunits remains elusive. Here, I observed the dynamic pore formation process using high-speed atomic force microscopy. During the oligomer transition process, each subunit was sequentially inserted into the membrane, propagating along the oligomer in a domino-like fashion (chain reaction). This process also occurred on hybrid oligomers containing wildtype and mutant subunits, which cannot insert into the membrane because of an introduced disulfide bond. Furthermore, propagation still occurred when an excessive force was added to hybrid oligomers in the prepore state. Based on the observed chain reactions, I estimate the free energies and forces that trigger the transition in a subunit. Furthermore, I hypothesize that the collaboration between subunits is related to the structure of their TMH regions and interactions between TMH-TMH and TMH-lipid molecules.
成孔蛋白(pfp)由包括致病菌在内的各种生物产生,并在靶细胞膜内形成孔。溶链素O (Streptolysin O, SLO)是一种由化脓性链球菌产生的PFP,在膜表面形成高阶低聚物。在这种预孔状态下,每个亚基结构域3中的多个α-螺旋以未展开的结构形式存在,并瞬间相互作用。它们随后转变为跨膜β发夹(TMHs)并形成直径为20-30 nm的孔。然而,在这个孔隙形成过程中,一个亚基的转变和亚基之间的协作的触发因素仍然是难以捉摸的。在这里,我使用高速原子力显微镜观察了动态孔隙形成过程。在低聚物过渡过程中,每个亚基依次插入膜中,沿着低聚物以多米诺骨牌般的方式传播(链式反应)。这一过程也发生在含有野生型和突变亚基的杂交低聚物上,由于引入了二硫键,这些低聚物不能插入膜中。此外,当杂化低聚物在预备状态下施加过大的力时,繁殖仍然发生。根据观察到的链式反应,我估计了触发亚基跃迁的自由能和力。此外,我假设亚基之间的协同作用与其TMH区域的结构以及TMH-TMH与TMH-脂质分子之间的相互作用有关。
期刊介绍:
The Journal of Membrane Biology is dedicated to publishing high-quality science related to membrane biology, biochemistry and biophysics. In particular, we welcome work that uses modern experimental or computational methods including but not limited to those with microscopy, diffraction, NMR, computer simulations, or biochemistry aimed at membrane associated or membrane embedded proteins or model membrane systems. These methods might be applied to study topics like membrane protein structure and function, membrane mediated or controlled signaling mechanisms, cell-cell communication via gap junctions, the behavior of proteins and lipids based on monolayer or bilayer systems, or genetic and regulatory mechanisms controlling membrane function.
Research articles, short communications and reviews are all welcome. We also encourage authors to consider publishing ''negative'' results where experiments or simulations were well performed, but resulted in unusual or unexpected outcomes without obvious explanations.
While we welcome connections to clinical studies, submissions that are primarily clinical in nature or that fail to make connections to the basic science issues of membrane structure, chemistry and function, are not appropriate for the journal. In a similar way, studies that are primarily descriptive and narratives of assays in a clinical or population study are best published in other journals. If you are not certain, it is entirely appropriate to write to us to inquire if your study is a good fit for the journal.