Premium
Requirement of the dephospho‐form of enzyme IIA Ntr for derepression of Escherichia coli K‐12 ilvBN expression
Author(s) -
Lee ChangRo,
Koo ByoungMo,
Cho SeungHyon,
Kim YuJung,
Yoon MiJeong,
Peterkofsky Alan,
Seok YeongJae
Publication year - 2005
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.1365-2958.2005.04834.x
Subject(s) - pep group translocation , derepression , biology , biochemistry , operon , enzyme , escherichia coli , mutant , leucine , phosphotransferase , transferase , threonine , amino acid , gene , phosphoenolpyruvate carboxykinase , serine , gene expression , psychological repression
Summary While the proteins of the phosphoenolpyruvate:carbohydrate phosphotransferase system (carbohydrate PTS) have been shown to regulate numerous targets, little such information is available for the nitrogen‐metabolic phosphotransferase system (nitrogen‐metabolic PTS). To elucidate the physiological role of the nitrogen‐metabolic PTS, we carried out phenotype microarray (PM) analysis with Escherichia coli K‐12 strain MG1655 deleted for the ptsP gene encoding the first enzyme of the nitrogen‐metabolic PTS. Together with the PM data, growth studies revealed that a ptsN (encoding enzyme IIA Ntr ) mutant became extremely sensitive to leucine‐containing peptides (LCPs), while both ptsP (encoding enzyme I Ntr ) and ptsO (encoding NPr) mutants were more resistant than wild type. The toxicity of LCPs was found to be due to leucine and the dephospho‐form of enzyme IIA Ntr was found to be necessary to neutralize leucine toxicity. Further studies showed that the dephospho‐form of enzyme IIA Ntr is required for derepression of the ilvBN operon encoding acetohydroxy acid synthase I catalysing the first step common to the biosynthesis of the branched‐chain amino acids.