6uzd

Publication Abstract from PubMed

Following assembly, the anthrax protective antigen (PA) forms an oligomeric translocon that unfolds and translocates either its lethal factor (LF) or edema factor (EF) into the host cell. Here, we report the cryo-EM structures of heptameric PA channels with partially unfolded LF and EF at 4.6 and 3.1-A resolution, respectively. The first alpha helix and beta strand of LF and EF unfold and dock into a deep amphipathic cleft, called the alpha clamp, which resides at the interface of two PA monomers. The alpha-clamp-helix interactions exhibit structural plasticity when comparing the structures of lethal and edema toxins. EF undergoes a largescale conformational rearrangement when forming the complex with the channel. A critical loop in the PA binding interface is displaced for about 4 A, leading to the weakening of the binding interface prior to translocation. These structures provide key insights into the molecular mechanisms of translocation-coupled protein unfolding and translocation.

Atomic structures of anthrax toxin protective antigen channels bound to partially unfolded lethal and edema factors.,Hardenbrook NJ, Liu S, Zhou K, Ghosal K, Hong Zhou Z, Krantz BA Nat Commun. 2020 Feb 11;11(1):840. doi: 10.1038/s41467-020-14658-6. PMID:32047164^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.