Premium
A mutant constitutive for aromatic permease
Author(s) -
Hadar R.,
Kuhn J.
Publication year - 1977
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(77)80124-5
Subject(s) - library science , chemistry , philosophy , computer science
The aromatic amino acids are transported in Escherichia coli by a combination of the general aromatic permease and permeases specific for each amino acid [ 1,2] . In contrast, D-tryptophan enters the cell only via the aromatic permease 131. Mutants lacking this permease have been isolated [2,3]. The aromatic permease is repressed by Ltyrosine [3] . Since trp dadR strains growing on D-tryptophan are absolutely dependent on aromatic permease activity, an attempt was made to isolate constitutive mutants on the basis of Ltyrosine resistance [3]. However the major class obtained involved changes in D-tryptophan oxidase [4] which like the aromatic permease is sensitive to competitive inhibition by Ltyrosine. We therefore sought compounds that are without effect on the oxidase. By using resistance to 5-methyltryptophan we were able to isolate the desired constitutive mutant.