Genetic Fine Structure of the Leucine Operon of Escherichia coli K-12
AUTOR(ES)
Somers, J. M.
RESUMO
The order of mutational sites in 10 independently isolated leucine auxotrophys of Escherichia coli K-12 was determined by three-point reciprocal transductions. The sites of mutation mapped in linear sequence in a cluster; all leucine auxotrophic mutations were cotransducible with mutations in the arabinose operon. The mutations were assigned to four complementation groups by abortive transduction tests, designated D, C, B, and A, reading in a clockwise direction from the arabinose operon. Enzyme analyses showed that strains with a mutation in gene A lacked α-isopropylmalate synthetase activity (EC 4.1.3), and those with a mutation in gene B lacked β-isopropylmalate dehydrogenase activity (EC 1.1.1). It is concluded that the gross structure of the leucine operon in E. coli is closely similar to, if not identical with, the gross structure of the leucine operon in Salmonella typhimurium.
