A single amino acid substitution in the A subunit of Escherichia coli enterotoxin results in a loss of its toxic activity

Takao Tsuji, Takashi Inoue, Akio Miyama, Keinosuke Okamoto, Takeshi Honda, Toshio Miwatani

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Abstract

A plasmid encoding a mutant gene of heat-labile enterotoxin (LT), produced by enterotoxigenic Escherichia coli, was induced by treatment of plasmid EWD 299 with hydroxylamine. A mutant strain of E. coli HB 101 carrying the mutant plasmid pTUH 6A produced a low toxic LT analogue (mutant LT), which was cross-reactive with anti-LT antibody. The mutant LT activity was less than 0.15 and 0.006% of the normal LT in the rabbit ileal loop test and in the rabbit skin permeability test, respectively. The amino acid composition of the mutant LT-B subunit was the same as that of the normal B subunit. Though the A2 fragment of the mutant LT was identical to normal LT by DNA analysis, the A1 fragment of the mutant LT differed from the normal A1 fragment in one amino acid at position 112; namely it had lysine instead of glutamic acid from the N terminus. These data suggest that glutamic acid at position 112 from the N terminus of the A1 fragment is important for the A subunit to express its biological activity.

Original languageEnglish
Pages (from-to)22520-22525
Number of pages6
JournalJournal of Biological Chemistry
Volume265
Issue number36
Publication statusPublished - Dec 25 1990
Externally publishedYes

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Poisons
Enterotoxins
Amino Acid Substitution
Escherichia coli
Plasmids
Substitution reactions
Amino Acids
Glutamic Acid
Rabbits
Enterotoxigenic Escherichia coli
Hydroxylamine
Bioactivity
Skin Tests
varespladib methyl
Lysine
Anti-Idiotypic Antibodies
Permeability
Skin
Hot Temperature
Genes

ASJC Scopus subject areas

  • Biochemistry

Cite this

A single amino acid substitution in the A subunit of Escherichia coli enterotoxin results in a loss of its toxic activity. / Tsuji, Takao; Inoue, Takashi; Miyama, Akio; Okamoto, Keinosuke; Honda, Takeshi; Miwatani, Toshio.

In: Journal of Biological Chemistry, Vol. 265, No. 36, 25.12.1990, p. 22520-22525.

Research output: Contribution to journalArticle

Tsuji, Takao ; Inoue, Takashi ; Miyama, Akio ; Okamoto, Keinosuke ; Honda, Takeshi ; Miwatani, Toshio. / A single amino acid substitution in the A subunit of Escherichia coli enterotoxin results in a loss of its toxic activity. In: Journal of Biological Chemistry. 1990 ; Vol. 265, No. 36. pp. 22520-22525.
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