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| - | [[Image:2ici.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_2ici| PDB=2ici | SCENE= }} | | {{STRUCTURE_2ici| PDB=2ici | SCENE= }} |
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| - | '''Crystal Structure of Streptococcal Pyrogenic Exotoxin I'''
| + | ===Crystal Structure of Streptococcal Pyrogenic Exotoxin I=== |
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| - | ==Overview==
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| - | Superantigens (SAgs) are potent microbial toxins that bind simultaneously to T cell receptors (TCRs) and class II major histocompatibility complex molecules, resulting in the activation and expansion of large T cell subsets and the onset of numerous human diseases. Within the bacterial SAg family, streptococcal pyrogenic exotoxin I (SpeI) has been classified as belonging to the group V SAg subclass, which are characterized by a unique, relatively conserved approximately 15 amino acid extension (amino acid residues 154 to 170 in SpeI; herein referred to as the alpha3-beta8 loop), absent in SAg groups I through IV. Here, we report the crystal structure of SpeI at 1.56 A resolution. Although the alpha3-beta8 loop in SpeI is several residues shorter than that of another group V SAg, staphylococcal enterotoxin serotype I, the C-terminal portions of these loops, which are located adjacent to the putative TCR binding site, are structurally similar. Mutagenesis and subsequent functional analysis of SpeI indicates that TCR beta-chains are likely engaged in a similar general orientation as other characterized SAgs. We show, however, that the alpha3-beta8 loop length, and the presence of key glycine residues, are necessary for optimal activation of T cells. Based on Vbeta-skewing analysis of human T cells activated with SpeI and structural models, we propose that the alpha3-beta8 loop is positioned to form productive intermolecular contacts with the TCR beta-chain, likely in framework region 3, and that these contacts are required for optimal TCR recognition by SpeI, and likely all other group V SAgs.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17303163}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17303163 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_17303163}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Varma, A K.]] | | [[Category: Varma, A K.]] |
| | [[Category: Streptococcal superantigen spei]] | | [[Category: Streptococcal superantigen spei]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:19:45 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:28:48 2008'' |
Revision as of 01:28, 29 July 2008
Template:STRUCTURE 2ici
Crystal Structure of Streptococcal Pyrogenic Exotoxin I
Template:ABSTRACT PUBMED 17303163
About this Structure
2ICI is a Single protein structure of sequence from Streptococcus pyogenes. Full crystallographic information is available from OCA.
Reference
Crystal structure of the streptococcal superantigen SpeI and functional role of a novel loop domain in T cell activation by group V superantigens., Brouillard JN, Gunther S, Varma AK, Gryski I, Herfst CA, Rahman AK, Leung DY, Schlievert PM, Madrenas J, Sundberg EJ, McCormick JK, J Mol Biol. 2007 Apr 6;367(4):925-34. Epub 2007 Jan 12. PMID:17303163
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