4EE2

Crystal Structure of Anthrax Protective Antigen K446M Mutant to 1.91-A Resolution

Summary for 4EE2

• Entry DOI: 10.2210/pdb4ee2/pdb
• Related: 1ACC 1TZO 3HVD 3TEW 3TEX
• Descriptor: Protective antigen, CALCIUM ION (3 entities in total)
• Functional Keywords: anthrax toxin, cell-binding, assembly, channel formation, protein translocation, toxin, transport protein
• Biological source: Bacillus anthracis (anthrax,anthrax bacterium)
• Cellular location: Secreted, extracellular space: P13423
• Total number of polymer chains: 1
• Total formula weight: 82982.19

Authors

Kintzer, A.F.,Krantz, B.A. (deposition date: 2012-03-28, release date: 2012-10-24, Last modification date: 2023-09-13)

Primary citation

Kintzer, A.F.,Tang, I.I.,Schawel, A.K.,Brown, M.J.,Krantz, B.A.
Anthrax toxin protective antigen integrates poly-gamma-D-glutamate and pH signals to sense the optimal environment for channel formation.
Proc.Natl.Acad.Sci.USA, 109:18378-18383, 2012

PubMed Abstract: Many toxins assemble into oligomers on the surface of cells. Local chemical cues signal and trigger critical rearrangements of the oligomer, inducing the formation of a membrane-fused or channel state. Bacillus anthracis secretes two virulence factors: a tripartite toxin and a poly-γ-d-glutamic acid capsule (γ-DPGA). The toxin's channel-forming component, protective antigen (PA), oligomerizes to create a prechannel that forms toxic complexes upon binding the two other enzyme components, lethal factor (LF) and edema factor (EF). Following endocytosis into host cells, acidic pH signals the prechannel to form the channel state, which translocates LF and EF into the host cytosol. We report γ-DPGA binds to PA, LF, and EF, exhibiting nanomolar avidity for the PA prechannel oligomer. We show PA channel formation requires the pH-dependent disruption of the intra-PA domain-2-domain-4 (D2-D4) interface. γ-DPGA stabilizes the D2-D4 interface, preventing channel formation both in model membranes and cultured mammalian cells. A 1.9-Å resolution X-ray crystal structure of a D2-D4-interface mutant and corresponding functional studies reveal how stability at the intra-PA interface governs channel formation. We also pinpoint the kinetic pH trigger for channel formation to a residue within PA's membrane-insertion loop at the inter-PA D2-D4 interface. Thus, γ-DPGA may function as a chemical cue, signaling that the local environment is appropriate for toxin assembly but inappropriate for channel formation.

PubMed: 23100533
DOI: 10.1073/pnas.1208280109

Experimental method

X-RAY DIFFRACTION (1.91 Å)