Isolation, genetic analysis, and characterization of Escherichia coli mutants with defects in the lacY gene
- 1 September 1977
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 131 (3), 830-838
- https://doi.org/10.1128/jb.131.3.830-838.1977
Abstract
LacY mutants (535) were isolated from an E. coli strain carrying the lactose operon on an F'' factor, without mutagenesis or after mutagenesis with 2-aminopurine or N-methyl-N''-nitro-N-nitrosoguanidine. Crosses against 48 independently isolated deletions ending in the lacY gene divided the gene into 36 deletion groups. Suppressibility studies with 7 nonsense suppressor strains classified 276 mutants as nonsense mutants and 78 as missense (or nonsuppressible) mutants. Mutants (179) were leaky and could not be so allocated, and 2 had small internal deletions. Nonsense mutants could in many cases be subdivided even within deletion groups on the basis of their suppressibility pattern, giving a total of 70 groups of nonsense mutants. Studies of these mutants allow the following conclusions: lactose and melibiose most probably do not have separate binding sites on the permease; the lacY region most likely consists of 1 cistron, and so both active transport and facilitated diffusion are functions of 1 protein; and there is probably no small defined region of the permease responsible for energy coupling of transport.This publication has 25 references indexed in Scilit:
- Lac repressor and Lac operatorProgress in Biophysics and Molecular Biology, 1976
- Mechanisms of active transport in isolated bacterial membrane vesicles. 28. Membrane potential and active transport in membrane vesicles from Escherichia coliBiochemistry, 1975
- INFORMATIONAL SUPPRESSIONAnnual Review of Genetics, 1970
- More mutant tyrosine transfer ribonucleic acidsJournal of Molecular Biology, 1970
- A mutant in Escherichia coli energy-uncoupled for lactose transport; A defect in the lactose-operonBiochemical and Biophysical Research Communications, 1970
- Fine structure of the gradient of polarity in the z gene of the lac operon of Escherichia coliJournal of Molecular Biology, 1970
- Directed transposition of the arabinose operon: A technique for the isolation of specialized transducing bacteriophages for any Escherichia coli geneJournal of Molecular Biology, 1969
- Frameshift Mutations in the Lactose Operon of E. coliPublished by Cold Spring Harbor Laboratory ,1966
- The role of permease in transportBiochimica et Biophysica Acta (BBA) - Specialized Section on Biophysical Subjects, 1964
- The specific mutagenic effect of base analogues on Phage T4Journal of Molecular Biology, 1959