Abstract
During DNA microarray analysis, we discovered that the GlnK-GlnL (formerly YcbA-YcbB) two-component system positively regulates the expression of the glsA-glnT (formerly ybgJ-ybgH) operon in response to glutamine in the culture medium on Northern analysis. As a result of gel retardation and DNase I footprinting analyses, we found that the GlnL protein interacts with a region (bases -13 to -56; +1 is the transcription initiation base determined on primer extension analysis of glsA-glnT) in which a direct repeat, TTTTGTN4TTTTGT, is present. Furthermore, the glsA and glnT genes were biochemically verified to encode glutaminase and glutamine transporter, respectively.