Role of glutamic acid 177 of the ricin toxin A chain in enzymatic inactivation of ribosomes.

D. Schlossman, D. Withers, P. Welsh, A. Alexander, J. Robertus, A. Frankel

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The gene for the A chain of ricin toxin was fused to a beta-galactosidase marker cistron via a DNA sequence encoding a short collagen linker, and the tripartite fusion protein was expressed in Escherichia coli. Site-specific mutagenesis was used to change glutamic acid residue 177 to aspartic acid or alanine. When the mutant proteins were expressed, purified, and tested quantitatively for enzymatic activity, the carboxylate function at position 177 was found not to be absolutely essential for ricin toxin A-chain catalysis.

Original languageEnglish (US)
Pages (from-to)5012-5021
Number of pages10
JournalMolecular and cellular biology
Issue number11
StatePublished - Nov 1989


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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