Identifying Selectivity Filters in Protein Biosensor for Ligand Screening

Abstract

Bacterial transcription initiation mainly occurs via two diverse RNA polymerases, namely 70 and 54. While 70 polymerase transcribes housekeeping genes and does not require any external activation to form transcriptionally competent open complex, the alternate polymerase 54 require regulatory proteins, typically AAA+ ATPases, that aid in converting the closed RNA polymerase complex to an active open state.1,2 External stimuli and environmental cues trigger 54 RNA polymerases that then govern several cellular processes ranging from speci c transport systems, alternative carbon catabolism as energy source, production of extracellular structures, and virulence determinants.3,4 The AAA+ sub-class of 54 activators proteins, also known as enhancer binding proteins (EBPs), possess a modular architecture and it is via their ubiquitous central AAA+ ATPase domain that they assemble into competent ATPase motors that in turn activate the 54 RNA polymerase holoenzyme.5,6 The assembly of the ATPase domain however, is regulated by the N-terminal signal sensing domain of EBPs.7,8 This N-terminal domain is a specialized domain that controls the whole downstream relay via sensing appropriate external stimuli.