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Identification of hypoxanthine and guanine as the co‐repressors for the purine regulon genes of Escherichia coli
Author(s) -
Meng L. M.,
Nygaard P.
Publication year - 1990
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1990.tb00580.x
Subject(s) - regulon , biology , escherichia coli , hypoxanthine , purine , guanine , identification (biology) , gene , repressor , purine metabolism , genetics , biochemistry , microbiology and biotechnology , transcription factor , nucleotide , botany , enzyme
Summary Addition of purine compounds to the growth medium of Escherichia coli and Salmonella typhimurium causes repressed synthesis of the purine biosynthetic enzymes. The repression is mediated through a regulatory protein, PurR. To identify the co‐repressor(s) of PurR, two approaches were used: (i) mutations were introduced into purine salvage genes and the effects of different purines on pur gene expression were determined; (ii) purine compounds which dictate the binding of the PurR protein to its operator DNA were resolved by gel retardation. Both the in vivo and the in vitro data indicated that guanine and hypoxanthine are co‐repressors. The toxic purine analogues 6‐mercaptopurjne and 6‐thioguanine also activated the binding of PurR to its operator DNA.