Resonance assignments of the cytoplasmic domain of ECF sigma factor W pathway protein YsdB from Bacillus subtilis.

Bacterial sigma (σ) factor, along with RNA polymerase core enzyme, initiates gene transcription from specific promoter regions and therefore regulates clusters of genes in response to a particular situation. The extracytoplasmic function (ECF) σ factors are a class of alternative σ factors that are often associated with environmental signal transduction across the bacterial membrane, in which external signal triggers the release of active σ from the membrane-anchored anti-σ factor. Gram-positive model organism Bacillus subtilis (B. subtilis) has seven ECF σ factors: σ, σ, σ, σ, σ, σ and σ. Although all these ECF σ factors were found to be involved in B. subtilis antibiotic resistance, σ is among the most studied and considered to play a pivotal role in responding to antimicrobial stresses. σ is under tight control and remains deactivated until exposure to external stimuli, after which proteases PrsW and RasP cleave the specific anti-sigma factor-RsiW to release and activate σ. Membrane anchored protein YsdB is a negative regulator of this activation, possibly via its direct interaction with PrsW and/or RsiW. Importantly, YsdB is well conserved among Bacilli, including pathogenic bacteria like Bacillus cereus. In this study, we describe the chemical shift assignments of the cytoplasmic domain of YsdB (29-130) of B. subtilis in solution as a basis for further interaction studies and structure determination. The near-complete assignment and the solution structure that will follow could provide a further understanding in σ regulation.