1ikp
From Proteopedia
(New page: 200px<br /><applet load="1ikp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ikp, resolution 1.45Å" /> '''Pseudomonas Aerugino...) |
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| - | [[Image:1ikp.jpg|left|200px]]<br /><applet load="1ikp" size=" | + | [[Image:1ikp.jpg|left|200px]]<br /><applet load="1ikp" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ikp, resolution 1.45Å" /> | caption="1ikp, resolution 1.45Å" /> | ||
'''Pseudomonas Aeruginosa Exotoxin A, P201Q, W281A mutant'''<br /> | '''Pseudomonas Aeruginosa Exotoxin A, P201Q, W281A mutant'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Exotoxin A of Pseudomonas aeruginosa asserts its cellular toxicity through | + | Exotoxin A of Pseudomonas aeruginosa asserts its cellular toxicity through ADP-ribosylation of translation elongation factor 2, predicated on binding to specific cell surface receptors and intracellular trafficking via a complex pathway that ultimately results in translocation of an enzymatic activity into the cytoplasm. In early work, the crystallographic structure of exotoxin A was determined to 3.0 A resolution, revealing a tertiary fold having three distinct structural domains; subsequent work has shown that the domains are individually responsible for the receptor binding (domain I), transmembrane targeting (domain II), and ADP-ribosyl transferase (domain III) activities, respectively. Here, we report the structures of wild-type and W281A mutant toxin proteins at pH 8.0, refined with data to 1.62 A and 1.45 A resolution, respectively. The refined models clarify several ionic interactions within structural domains I and II that may modulate an obligatory conformational change that is induced by low pH. Proteolytic cleavage by furin is also obligatory for toxicity; the W281A mutant protein is substantially more susceptible to cleavage than the wild-type toxin. The tertiary structures of the furin cleavage sites of the wild-type and W281 mutant toxins are similar; however, the mutant toxin has significantly higher B-factors around the cleavage site, suggesting that the greater susceptibility to furin cleavage is due to increased local disorder/flexibility at the site, rather than to differences in static tertiary structure. Comparison of the refined structures of full-length toxin, which lacks ADP-ribosyl transferase activity, to that of the enzymatic domain alone reveals a salt bridge between Arg467 of the catalytic domain and Glu348 of domain II that restrains the substrate binding cleft in a conformation that precludes NAD+ binding. The refined structures of exotoxin A provide precise models for the design and interpretation of further studies of the mechanism of intoxication. |
==About this Structure== | ==About this Structure== | ||
| - | 1IKP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa] with CL and NA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1IKP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_aeruginosa Pseudomonas aeruginosa] with <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=NA:'>NA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IKP OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Pseudomonas aeruginosa]] | [[Category: Pseudomonas aeruginosa]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: McKay, D | + | [[Category: McKay, D B.]] |
| - | [[Category: Trame, C | + | [[Category: Trame, C B.]] |
| - | [[Category: Wedekind, J | + | [[Category: Wedekind, J E.]] |
[[Category: CL]] | [[Category: CL]] | ||
[[Category: NA]] | [[Category: NA]] | ||
[[Category: all 3 exotoxin a domains]] | [[Category: all 3 exotoxin a domains]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:12:53 2008'' |
Revision as of 11:12, 21 February 2008
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Pseudomonas Aeruginosa Exotoxin A, P201Q, W281A mutant
Overview
Exotoxin A of Pseudomonas aeruginosa asserts its cellular toxicity through ADP-ribosylation of translation elongation factor 2, predicated on binding to specific cell surface receptors and intracellular trafficking via a complex pathway that ultimately results in translocation of an enzymatic activity into the cytoplasm. In early work, the crystallographic structure of exotoxin A was determined to 3.0 A resolution, revealing a tertiary fold having three distinct structural domains; subsequent work has shown that the domains are individually responsible for the receptor binding (domain I), transmembrane targeting (domain II), and ADP-ribosyl transferase (domain III) activities, respectively. Here, we report the structures of wild-type and W281A mutant toxin proteins at pH 8.0, refined with data to 1.62 A and 1.45 A resolution, respectively. The refined models clarify several ionic interactions within structural domains I and II that may modulate an obligatory conformational change that is induced by low pH. Proteolytic cleavage by furin is also obligatory for toxicity; the W281A mutant protein is substantially more susceptible to cleavage than the wild-type toxin. The tertiary structures of the furin cleavage sites of the wild-type and W281 mutant toxins are similar; however, the mutant toxin has significantly higher B-factors around the cleavage site, suggesting that the greater susceptibility to furin cleavage is due to increased local disorder/flexibility at the site, rather than to differences in static tertiary structure. Comparison of the refined structures of full-length toxin, which lacks ADP-ribosyl transferase activity, to that of the enzymatic domain alone reveals a salt bridge between Arg467 of the catalytic domain and Glu348 of domain II that restrains the substrate binding cleft in a conformation that precludes NAD+ binding. The refined structures of exotoxin A provide precise models for the design and interpretation of further studies of the mechanism of intoxication.
About this Structure
1IKP is a Single protein structure of sequence from Pseudomonas aeruginosa with and as ligands. Full crystallographic information is available from OCA.
Reference
Refined crystallographic structure of Pseudomonas aeruginosa exotoxin A and its implications for the molecular mechanism of toxicity., Wedekind JE, Trame CB, Dorywalska M, Koehl P, Raschke TM, McKee M, FitzGerald D, Collier RJ, McKay DB, J Mol Biol. 2001 Dec 7;314(4):823-37. PMID:11734000
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