Enterotoxicity and immunological properties of two mutant forms of Escherichia coli STIp with lysine or arginine substituted for the asparagine residue at position 11

Keinosuke Okamoto, Jun Yukitake, Kyoko Okamoto, Akio Miyama

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1 Citation (Scopus)


Two variants of Escherichia coli heat-stable enterotoxin Ip, in which the amino acid residue at position 11 was substituted with lysine or arginine, were purified to near homogeneity from the culture supernatants of toxin-producing mutant strains. Neither the purified heat-stable enterotoxin Ip(Lys-11) nor the purified heat-stable enterotoxin Ip(Arg-11) showed a positive response in the suckling mouse assay or in the mouse intestinal loop assay. Furthermore, live bacteria producing these mutant heat-stable Ip enterotoxins did not cause fluid accumulation in mouse intestinal loops, in contrast to bacteria producing native heat-stable enterotoxin Ip. Nevertheless, antisera raised against both heat-stable enterotoxin Ip(Lys-11) and heat-stable enterotoxin Ip(Arg-11) neutralized the enterotoxic activity of native heat-stable enterotoxin Ip. These results demonstrate that heat-stable enterotoxin Ip(Lys-11) and heat-stable enterotoxin Ip(Arg-11) lose enterotoxicity but retain epitopes which are common to native heat-stable enterotoxin Ip.

Original languageEnglish
Pages (from-to)191-195
Number of pages5
JournalFEMS Microbiology Letters
Issue number1-3
Publication statusPublished - Nov 1 1992
Externally publishedYes



  • Diarrhea
  • Escherichia coli
  • Heat-stable enterotoxin
  • Mutation
  • Vaccine

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Genetics

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