DegQ and SwrA differentially modulate protease production and flagellar motility in Bacillus subtilis

DegQ increases secreted protease production in stationary-phase Bacillus subtilis and inhibits swarming during exponential growth, with both effects requiring DegS and DegU.

• Why it matters: DegS–DegU controls adaptive responses, but how third-party modulators DegQ and SwrA differentially shape DegU-linked phenotypes is unclear.
• What they did: In the ancestral Bacillus subtilis strain functional for both proteins, the study compared DegQ and SwrA contributions to protease production and fla/che operon transcription, using DegS- and DegU-dependent mechanisms.
• The result: DegQ-mediated swarming inhibition involved reduced transcription within the long fla/che operon, while SwrA activated the fla/che promoter via DegU but not DegS and inhibited extracellular protease production by suppressing DegQ expression.