Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Two-component systems (TCSs) consisting of a membrane-anchored histidine kinase (HK) and a response regulator (RR) with DNA-binding activity. are major players in signal transduction in prokaryotes. Whereas most TCSs in
<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Escherichia coli</jats:named-content>
are well characterized, almost nothing is known about the LytS-like HK YehU and the corresponding LytTR-like RR YehT. To identify YehT-regulated genes, we compared the transcriptomes of
<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">E. coli</jats:named-content>
cells overproducing either YehT or the RR KdpE (control). The expression levels of 32 genes differed more than 8-fold between the two strains. A comprehensive evaluation of these genes identified
<jats:italic>yjiY</jats:italic>
as a target of YehT. Electrophoretic mobility shift assays with purified YehT confirmed that YehT interacts directly with the
<jats:italic>yjiY</jats:italic>
promoter. Specifically, YehT binds to two direct repeats of the motif ACC(G/A)CT(C/T)A separated by a 13-bp spacer in the
<jats:italic>yjiY</jats:italic>
promoter. The target gene
<jats:italic>yjiY</jats:italic>
encodes an inner membrane protein belonging to the CstA superfamily of transporters. In
<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">E. coli</jats:named-content>
cells growing in media containing peptides or amino acids as a carbon source,
<jats:italic>yjiY</jats:italic>
is strongly induced at the onset of the stationary-growth phase. Moreover, expression was found to be dependent on cyclic AMP (cAMP)/cAMP receptor protein (CRP). It is suggested that YehU/YehT participates in the stationary-phase control network.
</jats:p>