Mechanism of tryptophanase induction in Escherichia coli

John P. Bilezikian*, Raymond O.R. Kaempfer, Boris Magasanik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

The addition of l-tryptophan to uninduced Escherichia coli K12 leads to the formation of inactive enzyme precursor which can be converted to active l-tryptophanase in the absence of polypeptide synthesis. The accumulation of this precursor begins approximately one minute after the onset of induction. Conversion of the precursor to tryptophanase requires another one to two minutes. In pre-induced cells, inducer removal or infection with phage T6 causes an exponential decay of tryptophanase-forming capacity after a delay of approximately two minutes. However, the capacity to form the enzyme precursor decays with very little delay. These results suggest that the synthesis of tryptophanase-specific messenger RNA is completed within one minute after addition of inducer. Phage infection or inducer removal halt the continued accumulation of tryptophanase-specific messenger RNA, presumably by preventing the initiation of its synthesis. In F- cells, the capacity to form the tryptophanase precursor decays twice as fast after phage infection as after inducer removal; in F+ cells, phage infection does not lead to this accelerated decay. In view of similar results in the case of β-galactosidase, it is possible that infection with T-even phage decreases the functional stability of all host messenger RNA in F-, but not in F+ cells.

Original languageEnglish
Pages (from-to)495-506
Number of pages12
JournalJournal of Molecular Biology
Volume27
Issue number3
DOIs
StatePublished - 14 Aug 1967
Externally publishedYes

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