Open AccessEVOLUTION OF A REGULATED OPERON IN THE LABORATORY
Author(s) -
Barry G. Hall
Publication year - 1982
Publication title -
genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.792
H-Index - 246
eISSN - 1943-2631
pISSN - 0016-6731
DOI - 10.1093/genetics/101.3-4.335
Subject(s) - lac operon , lac repressor , operon , inducer , biology , repressor , permease , enzyme , lactose , beta galactosidase , trp operon , gene , l arabinose operon , mutation , lactose permease , genetics , regulation of gene expression , structural gene , gal operon , biochemistry , gene expression , escherichia coli
The evolution of new metabolic functions is being studied in the laboratory using the EBG system of E. coli as a model system. It is demonstrated that the evolution of lactose utilization by lacZ deletion strains requires a series of structural and regulatory gene mutations. Two structural gene mutations act to increase the activity of ebg enzyme toward lactose, and to permit ebg enzyme to convert lactose into allolactose, and inducer of the lac operon. A regulatory mutation increases the sensitivity of the ebg repressor of lactose, and permits sufficient ebg enzyme activity for growth. The resulting fully evolved ebg operon regulates its own expression, and also regulates the synthesis of the lactose permease.