Stress-response regulators tune enterobacterial common antigen synthesis to support acid and reactive nitrogen species stress resistance

Deleting regulator genes in Escherichia coli K-12 showed that GadX and MetJ directly repress wec operon transcription, and ECA supports growth under acidic pH and RNS stress.

• Why it matters: ECA is an OM/periplasm glycan barrier, but how its wec biosynthesis is controlled during envelope-damaging acid and reactive nitrogen species stress was unclear.
• What they did: The study measured wec promoter activity across deletions of 36 candidate regulator genes, then used in vitro binding to test direct control by GadX and MetJ.
• The result: wec promoter activity increased under acidic pH and RNS stress, and loss of ECA impaired growth under both conditions and fitness in acidic pH.