MopR from Acinetobacter calcoaceticus is an AAA+ Enhancer Binding Protein (belongs to NtrC family of transcriptional regulators) that act as molecular machine involved in the remodeling of DNA with σ-54 dependent RNA polymerases and initiate transcription. This remodeling is crucial for survival of the bacteria under stressful conditions such as those created by a toxic environment and/or by pathogenic bacteria for onset of virulence. MopR possesses a modular design consisting of three major domains; a N-terminal signal reception (A) domain which binds phenol, followed by a central ATPase(C) domain responsible for ATP hydrolysis and a C-terminally located DNA binding (D) domain. The ATP hydrolysis is foremost phenomena for DNA remodeling and is allosterically regulated via the phenol binding sensor domain. In the absence of phenol, the sensor domain adopts conformation that represses the ATPase activity whereas in the presence of the effector, derepression takes place which restore ATP hydrolysis. Additionally, it has been proposed that this event also results in signal transduction between domains and leads to shift in the protein population from a lower oligomeric (dimer) to a higher oligomeric assembly which then adopts a complex allostery mechanism of functioning. However, the exact mechanism of phenol binding as well as depression and the allosteric regulation both intra- and inter- subunits is poorly understood. Therefore, here by employing a combination of crystallography, computational and biochemical studies, we have identified the allosteric hotspots and also developed an allosteric model which describe the functioning of this mechanoenzymes. Additionally, since this protein has the ability to hydrolyse ATP upon sensing phenol and its derivatives, therefore, this was complimented to a read-out assay to design a biosensor. Further, we have carefully examined the crystal structure and have made mutations in the sensor domain, and have attempted to generate selectivity towards a broader spectrum of toxic aromatic compounds beyond its actual substrate scope for its application in the field of biosensors.

Elucidating the allosteric regulation in the NtrC family transcriptional regulator, MopR and its application in the field of biosensor

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.