Silhavy TJ, Boos W. Selection procedure for mutants defective in the beta-methylgalactoside transport system of Escherichia coli utilizing the compound 2R-glyceryl-beta-D-galactopyranoside.
J Bacteriol 1974;
120:424-32. [PMID:
4607764 PMCID:
PMC245779 DOI:
10.1128/jb.120.1.424-432.1974]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
A procedure has been devised that allows selection of mutants defective in the beta-methylgalactoside transport system (mgl) of Escherichia coli. This procedure utilizes the compound 2R-glyceryl-beta-d-galactopyranoside (glycerylgalactoside), which is known to be transported by only two transport system in E. coli, namely, the lactose and the beta-methylgalactoside transport systems. Mutants lacking glycerol-3-phosphate dehydrogenase (glpD) are sensitive to glycerol. Similarly, mutants lacking uridine diphosphate-galactose-4-epimerase (galE) are sensitive to galactose. Glycerylgalactoside is an inducer of the lactose operon and also a substrate for beta-galactosidase. Thus, a mgl(+)glpD galE lacY strain will not grow in the presence of glycerylgalactoside owing to accumulated glycerol-3-phosphate, galactose-1-phosphate, and uridine diphosphate-galactose. We have constructed such a strain and shown that mgl mutants can be obtained by selecting for those that grow in the presence of glycerylgalactoside.
Collapse