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Structure of anthrax lethal toxin prepore complex suggests a pathway for efficient cell entry

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ABSTRACT

Anthrax toxin is a tripartite complex in which the protective antigen moiety forms a pore through which lethal factor and edema factor are translocated. Fabre et al. reveal a mechanism for efficient translocation in their structure of the heptameric protective antigen prepore bound to three lethal factors.

No MeSH data available.


Alignment of (PA63)7–(LF)3 complexes. (A–C) The volume obtained after initial refinement is shown in three orientations. The densities corresponding to 1LF (C) are double as highlighted with the arrows. An atomic model was generated by rigid-body docking of LF (1JKY; Pannifer et al., 2001) and (PA63)7 (Lacy et al., 2004) into this volume and used as reference (D and E) after low pass filtering at 30 Å to ensure correct alignment of the large gap between 1LF and 3LF. Classification was performed without realigning the particles. The red arrows highlight the position of LF with respect to (PA63)7. ∼70% of the particles were found to be oriented as shown in F, whereas ∼30% were oriented as in G. The orientations of volumes shown in F and G are compared with H in the top view orientation. The yellow and cyan ovals indicate overlapping densities corresponding to LF.
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fig2: Alignment of (PA63)7–(LF)3 complexes. (A–C) The volume obtained after initial refinement is shown in three orientations. The densities corresponding to 1LF (C) are double as highlighted with the arrows. An atomic model was generated by rigid-body docking of LF (1JKY; Pannifer et al., 2001) and (PA63)7 (Lacy et al., 2004) into this volume and used as reference (D and E) after low pass filtering at 30 Å to ensure correct alignment of the large gap between 1LF and 3LF. Classification was performed without realigning the particles. The red arrows highlight the position of LF with respect to (PA63)7. ∼70% of the particles were found to be oriented as shown in F, whereas ∼30% were oriented as in G. The orientations of volumes shown in F and G are compared with H in the top view orientation. The yellow and cyan ovals indicate overlapping densities corresponding to LF.

Mentions: To generate the initial model, 11,061 particles were analyzed using the EMAN1 package (Ludtke et al., 1999). Reconstructions were generated using seven different starting models (Fig. S2) refined with an angular sampling of 14.3° and low pass filtering at 30 Å at each iteration. Refinement was run until volumes became similar. These volumes were then aligned and merged using the align3d and avg3d commands of EMAN giving the starting model. Refinement of this initial model was conducted using XMIPPv2.3 (Fourier reconstruction method; Scheres et al., 2008). Proper alignment of the gap was ensured by classification without realigning the particles (Fig. 2). The model obtained after classification was used for the final refinement.


Structure of anthrax lethal toxin prepore complex suggests a pathway for efficient cell entry
Alignment of (PA63)7–(LF)3 complexes. (A–C) The volume obtained after initial refinement is shown in three orientations. The densities corresponding to 1LF (C) are double as highlighted with the arrows. An atomic model was generated by rigid-body docking of LF (1JKY; Pannifer et al., 2001) and (PA63)7 (Lacy et al., 2004) into this volume and used as reference (D and E) after low pass filtering at 30 Å to ensure correct alignment of the large gap between 1LF and 3LF. Classification was performed without realigning the particles. The red arrows highlight the position of LF with respect to (PA63)7. ∼70% of the particles were found to be oriented as shown in F, whereas ∼30% were oriented as in G. The orientations of volumes shown in F and G are compared with H in the top view orientation. The yellow and cyan ovals indicate overlapping densities corresponding to LF.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5037343&req=5

fig2: Alignment of (PA63)7–(LF)3 complexes. (A–C) The volume obtained after initial refinement is shown in three orientations. The densities corresponding to 1LF (C) are double as highlighted with the arrows. An atomic model was generated by rigid-body docking of LF (1JKY; Pannifer et al., 2001) and (PA63)7 (Lacy et al., 2004) into this volume and used as reference (D and E) after low pass filtering at 30 Å to ensure correct alignment of the large gap between 1LF and 3LF. Classification was performed without realigning the particles. The red arrows highlight the position of LF with respect to (PA63)7. ∼70% of the particles were found to be oriented as shown in F, whereas ∼30% were oriented as in G. The orientations of volumes shown in F and G are compared with H in the top view orientation. The yellow and cyan ovals indicate overlapping densities corresponding to LF.
Mentions: To generate the initial model, 11,061 particles were analyzed using the EMAN1 package (Ludtke et al., 1999). Reconstructions were generated using seven different starting models (Fig. S2) refined with an angular sampling of 14.3° and low pass filtering at 30 Å at each iteration. Refinement was run until volumes became similar. These volumes were then aligned and merged using the align3d and avg3d commands of EMAN giving the starting model. Refinement of this initial model was conducted using XMIPPv2.3 (Fourier reconstruction method; Scheres et al., 2008). Proper alignment of the gap was ensured by classification without realigning the particles (Fig. 2). The model obtained after classification was used for the final refinement.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Anthrax toxin is a tripartite complex in which the protective antigen moiety forms a pore through which lethal factor and edema factor are translocated. Fabre et al. reveal a mechanism for efficient translocation in their structure of the heptameric protective antigen prepore bound to three lethal factors.

No MeSH data available.