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Abstract:
Ss-LrpB is an Lrp-like transcriptional regulator from
Sulfolobus solfataricus. Previously, in vitro binding of
Ss-LrpB to the control region of its own gene has
been extensively studied. However, nothing was
known about the physiological role of this regulator
yet. Here, using the knowledge of the DNA-binding
sequence specificity of Ss-LrpB, several potential
binding sites were predicted in silico in promoter
regions of genes located adjacently to the Ss-lrpB
gene. These genes include an operon encoding a
pyruvate ferredoxin oxidoreductase (porDAB) and
two genes encoding putative permeases. In vitro
protein–DNA interaction studies allowed the identification
of the Ss-LrpB binding sites in the cognate
control regions. Intriguingly, the binding site organization
in the por operator is identical to that in the
Ss-lrpB control region. An Ss-lrpB gene disruption
mutant was constructed and the gene expression of
the above-mentioned targets in this mutant was
analysed by qRT-PCR and compared with isogenic
wild type. Our data demonstrate that in vivo Ss-LrpB
acts as an activator at the promoters of the three
predicted targets. Based on these results, it appears
that not all regulators belonging to the archaeal Lrp
family perform a function related to the amino acid
metabolism, unlike the bacterial Lrp-like regulators
