EXPERIMENTAL EVOLUTION OF A NEW ENZYMATIC FUNCTION. II. EVOLUTION OF MULTIPLE FUNCTIONS FOR EBG ENZYME IN E. COLI
Open Access
- 20 July 1978
- journal article
- research article
- Published by Oxford University Press (OUP) in Genetics
- Vol. 89 (3) , 453-465
- https://doi.org/10.1093/genetics/89.3.453
Abstract
The evolution of ebgo enzyme of Escherichia coli, an enzyme which is unable to hydrolyze lactose, lactulose, lactobionate, or galactose-arabinoside effectively, has been directed in successive steps so that the evolved enzyme is able to hydrolyze these galactosides effectively. I show that in order for a strain of E. coli with a lacZ deletion to evolve the ability to use lactobionate as a carbon source, a series of mutations must occur in the ebg genes, and that these mutations must be selected in a particular order. The ordered series of mutations constitutes an obligatory evolutionary pathway for the acquisition of a new function for ebgo enzyme. A comparison of newly evolved strains with parental strains shows that when ebg enzyme acquires a new function, its old functions often suffer; but that in several cases old functions are either unaffected or are improved. I conclude that divergence of functions catalyzed by an enzyme need not require gene duplication.This publication has 2 references indexed in Scilit: