Document Detail


Analyzing of expression of novel polypeptide complexes consisting of Shiga toxin B subunit and Adherence Fimbriae of Escherichia coli based on in silico modeling.
MedLine Citation:
PMID:  22527278     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Enterohemorrhagic (EHEC) and enteroaggregative (EAEC) are two pathotypes of diarrheagenic Escherichia coli. EAEC strains express adhesins called aggregate adherence fimbriae (AAFs) which the bacteria use to adhere to intestinal mucosa. EHEC virulence factor is Shiga toxin which belongs to the AB5 toxin family. B subunit, the nontoxic part of Shiga toxin (StxB), forms a homo pentamer and is responsible for binding to target cells. StxB has recently been proven to have adjuvant activity. In the current study we fused StxB encoding gene to 3' end of genes encoding two variants of AAFs, i.e., AAF/I and AAF/II. The in silico studies on tertiary structure and biochemical characteristics of Shiga toxin A subunit (StxA) revealed more resemblance to AAF/II than AAF/I. The constructs were prepared in a way that StxB could imitate its natural structure (pentamer formation) and its position (C-terminus) in the native toxin complex. The expression of these constructs showed the formation of AAF/II-B as a protein complex but with lower molecular mass than its expected size. In contrast, the AAF/I-B complex was not formed. Overall, the results of in silico studies and expression experiments together revealed that despite AAF/II-B expression, StxB failed to form pentamer. Therefore the observed protein complex has lower molecular mass. Since StxB is bound to AAF/II through disulfide bond, this bond prevents pentamer formation of StxB. However, due to the lack of disulfide bond between AAF/I and StxB, no protein complex is formed, thus StxB maintains its pentamer structure.
Authors:
Zeinab Noroozian; Mana Oloomi; Saeid Bouzari
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-04-24
Journal Detail:
Title:  Journal of molecular modeling     Volume:  18     ISSN:  0948-5023     ISO Abbreviation:  J Mol Model     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-08-29     Completed Date:  2013-01-14     Revised Date:  2013-03-15    
Medline Journal Info:
Nlm Unique ID:  9806569     Medline TA:  J Mol Model     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  4131-9     Citation Subset:  IM    
Affiliation:
Department of Molecular biology, Pasteur Institute of Iran, Tehran, Iran, 1316943551.
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MeSH Terms
Descriptor/Qualifier:
Adhesins, Escherichia coli / chemistry,  metabolism*
Bacterial Adhesion
Blotting, Western
Computational Biology / methods*
Disulfides / metabolism
Electrophoresis, Polyacrylamide Gel
Escherichia coli / metabolism*
Escherichia coli Proteins / chemistry,  metabolism*
Fimbriae Proteins / chemistry,  metabolism*
Models, Molecular*
Peptides / chemistry,  metabolism*
Protein Binding
Protein Structure, Secondary
Protein Structure, Tertiary
Protein Subunits / chemistry,  metabolism
Shiga Toxins / chemistry,  metabolism*
Chemical
Reg. No./Substance:
0/AafA protein, E coli; 0/Adhesins, Escherichia coli; 0/AggA protein, E coli; 0/Disulfides; 0/Escherichia coli Proteins; 0/Peptides; 0/Protein Subunits; 0/Shiga Toxins; 0/stxB toxin; 147680-16-8/Fimbriae Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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