1fnw
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(New page: 200px<br /><applet load="1fnw" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fnw, resolution 3.9Å" /> '''CRYSTAL STRUCTURE OF ...)
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Revision as of 12:57, 20 November 2007
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CRYSTAL STRUCTURE OF STREPTOCOCCAL PYROGENIC EXOTOXIN A
Overview
The streptococcal pyrogenic toxins A, B, and C (SPEA, SPEB, and SPEC) are, responsible for the fever, rash, and other toxicities associated with, scarlet fever and streptococcal toxic shock syndrome. This role, together, with the ubiquity of diseases caused by Streptococcus pyogenes, have, prompted structural analyses of SPEA by several groups. Papageorgiou et, al. (1999) have recently reported the structure of SPEA crystallized in, the absence of zinc. Zinc has been shown to be important in the ability of, some staphylococcal and streptococcal toxins to stimulate proliferation of, CD4+ T-cells. Since cadmium is more electron dense than zinc and typically, binds interchangeably, we grew crystals in the presence of 10 mM CdCl2., Crystals have been obtained in three space groups, and the structure in, the P2(1)2(1)2(1) crystal form has been refined to 1.9 A resolution. The, structural analysis revealed an identical tetramer as well as a novel, tetrahedral cluster of cadmium in all three crystal forms on a disulfide, loop encompassing residues 87-98. No cadmium was bound at the site, homologous to the zinc site in staphylococcal enterotoxins C (SECs), despite the high structural homology between SPEA and SECs. Subsequent, soaking of crystals grown in the presence of cadmium in 10 mM ZnCl2 showed, that zinc binds in this site (indicating it can discriminate between zinc, and cadmium ions) using the three ligands (Asp77, His106, and His110), homologous to the SECs plus a fourth ligand (Glu33).
About this Structure
1FNW is a Single protein structure of sequence from Streptococcus pyogenes with CD as ligand. Full crystallographic information is available from OCA.
Reference
Structure of streptococcal pyrogenic exotoxin A reveals a novel metal cluster., Earhart CA, Vath GM, Roggiani M, Schlievert PM, Ohlendorf DH, Protein Sci. 2000 Sep;9(9):1847-51. PMID:11045630
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