Purification of the STBenterotoxin of Escherichia coli and the role of selected amino acids on its secretion, stability and toxicity
| Autor: | L A, Dreyfus, R G, Urban, S C, Whipp, C, Slaughter, K, Tachias, Y M, Kupersztoch, L A, Drefus |
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| Rok vydání: | 1992 |
| Předmět: |
DNA
Bacterial Proteolysis Bacterial Toxins Molecular Sequence Data Enterotoxin Biology medicine.disease_cause Microbiology Enterotoxins Structure-Activity Relationship Residue (chemistry) Escherichia coli medicine Amino Acid Sequence Disulfides Amino Acids Site-directed mutagenesis Molecular Biology chemistry.chemical_classification Base Sequence medicine.diagnostic_test Edman degradation Escherichia coli Proteins Periplasmic space Amino acid Biochemistry chemistry Mutagenesis Site-Directed Electrophoresis Polyacrylamide Gel |
| Zdroj: | Molecular Microbiology. 6:2397-2406 |
| ISSN: | 1365-2958 0950-382X |
| DOI: | 10.1111/j.1365-2958.1992.tb01414.x |
| Popis: | Summary The methanol-insolouble heat-stable enterotoxin of Escherichia coli (STB) was purified and characterized by automated Edman degradation and tryptic peptide analysis. The amino-terminal residue, Ser-24, confirmed that the first 23 amino acids inferred from the gene sequence were removed during translocation through the E. coli inner membrane. Tryptic peptide analysis coupled with automated Edman degradation revealed that disulphide bonds are formed between residues Cys-33 and Cys-71 and between Cys-44 and Cys-59. Oligonucleotide-directed mutagenesis performed on the STB gene demonstrated that disulphide bond formation does not precede translocation of the polypeptide through the inner membrane and that disulphide bridge formation is a periplasmic event; apparently, elimination of either of two disulphides of STB renders the molecule susceptible to periplasmic proteolysis. In addition, a loop defined by the Cys-44—Cys-59 bond contains at least two amino acids (Arg-52 and Asp-53) required for STQ toxic activity. |
| Databáze: | OpenAIRE |
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