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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Interactions of anthrax lethal factor with protective antigen defined by site-directed spin labeling
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Interactions of anthrax lethal factor with protective antigen defined by site-directed spin labeling

机译:炭疽致死因子与保护性抗原的相互作用,定点旋转标记

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摘要

The protective antigen (PA) moiety of anthrax toxin forms oligo-meric pores that translocate the enzymatic moieties of the toxin -lethal factor (LF) and edema factor (EF)-across the endosomal membrane of mammalian cells. Here we describe site-directed spin-labeling studies that identify interactions of LF with the prepore and pore conformations of PA. Our results reveal a direct interaction between the extreme N terminus of LF (residues 2-5) and the φ-clamp, a structure within the lumen of the pore that catalyzes translocation. Also, consistent with a recent crystallographic model, we find that, upon binding of the translocation substrate to PA, LF helix a1 separates from helices α2 and α3 and binds in the a-clamp of PA. These interactions, together with the binding of the globular part of the N-terminal domain of LF to domain 1' of PA, indicate that LF interacts with the PA pore at three distinct sites. Our findings elucidate the state from which translocation of LF and EF proceeds through the PA pore.
机译:炭疽毒素的保护性抗原(PA)部分形成寡聚的孔,该孔可跨哺乳动物细胞的内体膜转运毒素-致命因子(LF)和水肿因子(EF)的酶部分。在这里,我们描述了定点旋转标记研究,该研究确定了LF与PA的前孔和孔构象的相互作用。我们的结果揭示了LF的极端N末端(残基2-5)与φ钳之间的直接相互作用,φ钳是孔腔内催化移位的结构。同样,与最近的晶体学模型一致,我们发现,在易位底物与PA结合后,LF螺旋a1与螺旋α2和α3分离并结合在PA的a钳位中。这些相互作用,以及LF的N-末端结构域的球形部分与PA的结构域1'的结合,表明LF在三个不同的位点与PA孔相互作用。我们的发现阐明了LF和EF通过PA孔进行移位的状态。

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