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Toxins (Basel). 2017 Sep 22;9(10). pii: E298. doi: 10.3390/toxins9100298.

Asymmetric Cryo-EM Structure of Anthrax Toxin Protective Antigen Pore with Lethal Factor N-Terminal Domain.

Author information

1
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. amachen@kumc.edu.
2
Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA. akkaladevin@missouri.edu.
3
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. ctrecazzi@kumc.edu.
4
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. poneil@kumc.edu.
5
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. srayanta@gmail.com.
6
Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, PA 18015, USA. yfqi@chem.ecnu.edu.cn.
7
National Center for Macromolecular Imaging, Baylor University, Houston TX 77030, USA. rdillard@gmail.com.
8
Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, PA 18015, USA. woi216@lehigh.edu.
9
Department of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA. gogole@umkc.edu.
10
Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA. whiteto@missouri.edu.
11
Electron Microscopy Core Facility, University of Missouri, Columbia, MO 65211, USA. whiteto@missouri.edu.
12
Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. mfisher1@kumc.edu.

Abstract

The anthrax lethal toxin consists of protective antigen (PA) and lethal factor (LF). Understanding both the PA pore formation and LF translocation through the PA pore is crucial to mitigating and perhaps preventing anthrax disease. To better understand the interactions of the LF-PA engagement complex, the structure of the LFN-bound PA pore solubilized by a lipid nanodisc was examined using cryo-EM. CryoSPARC was used to rapidly sort particle populations of a heterogeneous sample preparation without imposing symmetry, resulting in a refined 17 Å PA pore structure with 3 LFN bound. At pH 7.5, the contributions from the three unstructured LFN lysine-rich tail regions do not occlude the Phe clamp opening. The open Phe clamp suggests that, in this translocation-compromised pH environment, the lysine-rich tails remain flexible and do not interact with the pore lumen region.

KEYWORDS:

anthrax toxin; cryo-EM; cryoSPARC; lethal factor; nanodisc; pore formation; protective antigen; translocation

PMID:
28937604
PMCID:
PMC5666345
DOI:
10.3390/toxins9100298
[Indexed for MEDLINE]
Free PMC Article

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