Role of arginine 180 and glutamic acid 177 of ricin toxin a chain in enzymatic inactivation of ribosomes

Arthur Frankel, Phil Welsh, Jane Richardson, Jon D. Robertus

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Abstract

The gene for ricin toxin A chain was modified by site-specific mutagenesis to change arginine 180 to alanine, glutamine, methionine, lysine, or histidine. Separately, glutamic acid 177 was changed to alanine and glutamic acid 208 was changed to aspartic acid. Both the wild-type and mutant proteins were expressed in Escherichia coli and, when soluble, purified and tested quantitatively for enzyme activity. A positive charge at position 180 was found necessary for solubility of the protein and for enzyme activity. Similarly, a negative charge with a proper geometry in the vicinity of position 177 was critical for ricin toxin A chain catalysis. When glutamic acid 177 was converted to alanine, nearby glutamic acid 208 could largely substitute for it. This observation provided valuable structural information concerning the nature of second-site mutations.

Original languageEnglish (US)
Pages (from-to)6257-6263
Number of pages7
JournalMolecular and cellular biology
Volume10
Issue number12
DOIs
StatePublished - Jan 1 1990

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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