title: Reduced expression of the isoleucine and valine enzymes in integration host factor mutants of Escherichia coli.
abstract: The level of the isoleucine and valine (Ilv) enzymes specified by the ilvB and ilvGEDA operons is reduced in integration host factor mutants (himA and himD) of Escherichia coli K-12. Growth inhibition of these strains in minimal medium can be explained by the decreased amounts of one of the Ilv enzymes, acetohydroxy acid synthase I (AHASI). No growth inhibition, or reduction in AHASI activity, was found in a himA derivative of a mutant strain containing high constitutive levels of AHASI. A strong correlation was observed in himA strains between the reduced amount of the Ilv enzymes and of Ilv-specific messenger RNA. These data suggest that integration host factor may be a positive effector for transcription of the ilvB and ilvGEDA operons.
mesh_terms: D000095:Acetolactate Synthase / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D005786:Gene Expression Regulation; D019426:Integrases; D007532:Isoleucine / Q000235:genetics*; D009154:Mutation; D014633:Valine / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D007532:Isoleucine; D000095:Acetolactate Synthase; D019426:Integrases; D014633:Valine