Operator-constitutive mutants in the threonine operon of Escherichia coli K-12.
نویسندگان
چکیده
Three Escherichia coli K-12 mutant strains resistant to DL-alpha-amino-beta-hydroxyvaleric acid were isolated in which the expression of the thr operon is constitutive. The localization and dominance properties of the mutations involved, called thrO, are those of operator mutations. The gene sequence is OABC as suggested by earlier studies.
منابع مشابه
Study of Organic Solvent Tolerance and Increased Antibiotic Resistance Properties in E. coli gyrA Mutants
Ciprofloxacin is one of the most widely used antibiotics for the treatment of several infections caused by Gram-negative bacteria, like E. coli. Changes in gyrA, encoding GyrA subunit of DNA gyrase, cause the resistance to ciprofloxacin. Some ciprofloxacin resistant gyrA mutants acquired constitutive expression of marRAB operon due to the gaining mutations in marR, a repressor of this operon...
متن کاملStudy of Organic Solvent Tolerance and Increased Antibiotic Resistance Properties in E. coli gyrA Mutants
Ciprofloxacin is one of the most widely used antibiotics for the treatment of several infections caused by Gram-negative bacteria, like E. coli. Changes in gyrA, encoding GyrA subunit of DNA gyrase, cause the resistance to ciprofloxacin. Some ciprofloxacin resistant gyrA mutants acquired constitutive expression of marRAB operon due to the gaining mutations in marR, a repressor of this operon...
متن کاملCharacterization of the operator sites of the exu regulon in Escherichia coli K-12 by operator-constitutive mutations and repressor titration.
In Escherichia coli, the exu regulon of the hexuronate system involves the three exuT, uxaCA and uxaB operons and is under the negative control of the exuR regulatory gene product. The technique developed by Casadaban, Chou and Cohen was employed to construct two plasmids containing operon fusions in which the lactose genes were fused to the uxaCA and exuT operons. These fusions were transferre...
متن کاملThreonyl-transfer ribonucleic acid synthetase and the regulation of the threonine operon in Escherichia coli.
Two threonine-requiring mutants with derepressed expression of the threonine operon were isolated from an Escherichia coli K-12 strain containing two copies of the thr operon. One of them carries a leaky mutation in ilvA (the structural gene for threonine deaminase), which creates an isoleucine limitation and therefore derepression of the thr operon. In the second mutant, the enzymes of the thr...
متن کاملExpression of acrA and acrB Genes in Esherichia coli Mutants with or without marR or acrR Mutations
Objective(s): The major antibiotic efflux pump of Esherichia coli is AcrAB-TolC. The first part of the pump, AcrAB, is encoded by acrAB operon. The expression of this operon can be kept elevated by overexpression of an activator, MarA following inactivation of MarR and AcrR repressors due to mutation in encoding genes, marR and acrR, respectively. The aims of this research were to us...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of bacteriology
دوره 124 3 شماره
صفحات -
تاریخ انتشار 1975