Use of Tn5lac to study expression of genes required for production of the antibiotic TA

S. Tolchinsky*, N. Fuchs, M. Varon, E. Rosenberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The β-galactosidase activities arising from Tn5lac insertions in several genes required for antibiotic TA production were measured under different growth conditions. In all of the non-TA-producing mutants, the β- galactosidase specific activity was higher when the cells were grown in nutrient-limited 0.5CTS medium (0.5% Casitone plus alanine, serine, and glucose) than in rich 2CT medium (2% Casitone). One of the mutants, 420, had low β-galactosidase specific activity in both media. The other seven mutants containing inserts in genes essential for TA production had specific activities of 139 to 367 U/mg of protein in 0.5CTS medium and 11 to 48 U/mg of protein in 2CT medium. The β-galactosidase specific activities of two strains, 1030 and 420, increased during exponential growth in 0.5CTS medium. The β-galactosidase specific activities of both strains increased greatly when the cells were grown in the presence of magnesium phosphate, which traps ammonium ions. The Tn5lac insertions in 1030 and 420 were used to screen for mutants with increased levels of transcription. An N-methyl-N'-nitro-N- nitrosoguanidine-induced mutation in 1030 that mapped 17 kb from the Ω1010 insert increased the specific activity of β-galactosidase 21 times in 2CT medium. The regulatory mutation appears to release the repression caused by 2CT medium. A UV-induced mutation in 420 increased the β-galactosidase specific activity 1.4 to 2.4 times. Medium conditions that affect the transcription of TA genes are discussed in terms of enhanced antibiotic TA production.

Original languageEnglish
Pages (from-to)2322-2327
Number of pages6
JournalAntimicrobial Agents and Chemotherapy
Volume36
Issue number10
DOIs
StatePublished - 1992

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