3tez

Crystal Structure of Anthrax Protective Antigen Mutant S337C N664C and dithiolacetone modified to 1.8-A resolution

spinqualitylabelsall models 3tez, resolution 1.83Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3tez is a 1 chain structure with sequence from Bacillus anthracis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.83Å Ligands: ACN, CA, MXE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PAG_BACAN One of the three proteins composing the anthrax toxin, the agent which infects many mammalian species and that may cause death. PA binds to a receptor (ATR) in sensitive eukaryotic cells, thereby facilitating the translocation of the enzymatic toxin components, edema factor and lethal factor, across the target cell membrane. PA associated with LF causes death when injected, PA associated with EF produces edema. PA induces immunity to infection with anthrax. Publication Abstract from PubMed The three protein components of anthrax toxin are nontoxic individually, but they form active holotoxin complexes upon assembly. The role of the protective antigen (PA) component of the toxin is to deliver two other enzyme components, lethal factor and edema factor, across the plasma membrane and into the cytoplasm of target cells. PA is produced as a proprotein, which must be proteolytically activated; generally, cell surface activation is mediated by a furin family protease. Activated PA can then assemble into one of two noninterconverting oligomers, a homoheptamer and a homooctamer, which have unique properties. Herein we describe molecular determinants that influence the stoichiometry of PA in toxin complexes. By tethering PA domain 4 (D4) to domain 2 with two different-length cross-links, we can control the relative proportions of PA heptamers and octamers. The longer cross-link favors octamer formation, whereas the shorter one favors formation of the heptamer. X-ray crystal structures of PA (up to 1.45 A resolution), including these cross-linked PA constructs, reveal that a hinge-like movement of D4 correlates with the relative preference for each oligomeric architecture. Furthermore, we report the conformation of the flexible loop containing the furin cleavage site and show that, for efficient processing, the furin site cannot be moved ~5 or 6 residues within the loop. We propose that there are different orientations of D4 relative to the main body of PA that favor the formation of either the heptamer or the octamer. Domain flexibility modulates the heterogeneous assembly mechanism of anthrax toxin protective antigen.,Feld GK, Kintzer AF, Tang II, Thoren KL, Krantz BA J Mol Biol. 2012 Jan 6;415(1):159-74. Epub 2011 Oct 31. PMID:22063095 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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