Specific Action of 4-Nitropyridine 1-Oxide on Escherichia coli K-12 Pro+ Strains Leading to the Isolation of Proline-Requiring Mutants: Isolation and Characterization of Pro− Mutants

AUTOR(ES)

Inuzuka, Manabu

RESUMO

A specific action of 4-nitropyridine 1-oxide on Escherichia coli K-12 Pro+ strains leading to highly efficient, selective isolation of Pro− mutants is described. Incubation of Pro+ cells with a sublethal concentration of 4-nitropyridine 1-oxide in Penassay broth gave Pro− mutants, which lacked either the biosynthetic pathway of proline from glutamic acid to glutamyl γ-phosphate (proB−) or the pathway from glutamyl γ-phosphate to glutamic γ-semialdehyde (proA−) or both. Pro− mutants, which have the metabolic block between Δ1 pyrroline-5-carboxylate (the cyclized dehydration product of glutamic γ-semialdehyde) and proline (proC−) were not found among survivors. Treatment of Pro+ cells with N-methyl-N′-nitro-N-nitrosoguanidine led to isolation of all three types of Pro− mutants, suggesting that the action of 4-nitropyridine 1-oxide on Pro+ cells is apparently distinct from the action of N-methyl-N′-nitro-N-nitrosoguanidine. F-duction and interrupted mating experiments led to determination of the correlation between proline loci and the biosynthetic pathway of proline from glutamic acid.

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