Evolution of a Second Gene for β-Galactosidase in Escherichia coli
- 1 June 1973
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 70 (6), 1841-1845
- https://doi.org/10.1073/pnas.70.6.1841
Abstract
Mutants of E. coli K12 with deletions of the beta-galactosidase gene (lacZ) can reacquire the ability to hydrolyze beta-galactosides during prolonged intense selection for growth on lactose. Full lactose competence is restored through a sequence of at least five mutations. Cell extracts of these derived strains hydrolyze o-nitrophenyl-beta-D-galactoside, the standard substrate for assay of beta-galactosidase. The enzyme responsible for this activity differs in its immunological, kinetic, and sedimentation characteristics from the lacZ beta-galactosidase of wild-type E. coli. Its genetic determinant, designated ebg-5, maps at 59 min on the E. coli chromosome, whereas the lac operon maps at 10 min. We suggest that a gene not involved in lactose utilization has been progressively changed into a form capable of specifying a beta-galactosidase and that this process is similar to that whereby genes with new functions are evolved by natural selection.Keywords
This publication has 18 references indexed in Scilit:
- The tolC locus in Escherichia coli K12.1971
- Classification and intragenic position of mutations in the β-galactosidase gene of Escherichia coliMolecular Genetics and Genomics, 1969
- Genetic evidence for the disposition of the substrate binding site of beta-galactosidase.Proceedings of the National Academy of Sciences, 1968
- Frameshift Mutations in the Lactose Operon of E. coliPublished by Cold Spring Harbor Laboratory ,1966
- Effect of Nonsense Mutations on Translation of the Lactose Operon of Escherichia coliCold Spring Harbor Symposia on Quantitative Biology, 1966
- PURIFICATION COMPOSITION AND MOLECULAR WEIGHT OF BETA-GALACTOSIDASE OF ESCHERICHIA COLI K121965
- [THE PROMOTOR, A GENETIC ELEMENT NECESSARY TO THE EXPRESSION OF AN OPERON].1964
- A Method for Determining the Sedimentation Behavior of Enzymes: Application to Protein MixturesJournal of Biological Chemistry, 1961
- THE EFFECT OF ACRIDINE DYES ON MATING TYPE FACTORS IN ESCHERICHIA COLIProceedings of the National Academy of Sciences, 1960
- The determination of enzyme inhibitor constantsBiochemical Journal, 1953