Abstract:
Therapeutic strategies have been reported that depend on synthetic network devices in which a uratesensing
transcriptional regulator detects pathological levels of urate and triggers production or release
of urate oxidase. The transcription factor involved, HucR, is a member of the multiple antibiotic resistance
(MarR) protein family. We show that protonation of stacked histidine residues at the pivot point of long
helices that form the scaffold of the dimer interface leads to reversible formation of a molten globule
state and significantly attenuated DNA binding at physiological temperatures. We also show that binding of
urate to symmetrical sites in each protein lobe is communicated via the dimer interface. This is the first
demonstration of regulation of a MarR family transcription factor by pH-dependent interconversion
between a molten globule and a compact folded state. Our data further suggest that HucR may be
utilized in synthetic devices that depend on detection of pH changes.
