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Revision as of 03:19, 28 September 2013

GadA-RBS is a pH sensitive promoter

GadA-RBS is a pH sensitive promoter that has been shown to initiate transcription at low pH.

Usage and Biology

The gadA gene is a part of the gad system, which is an acid-inducible glutamate decarboxylase-based acid resistance system that enables the survival of E. coli under acid stress conditions. GadA is a gene encoding a glutamate decarboxylase. The process of decarboxylating glutamate consumes protons that leach into the cell under acid stress. In this manner, the gad system manages protons that would otherwise drop the cellular pH below levels at which E. coli could survive.

The function of the gad system explains why these genes experience high transcription levels at low pH. Despite this functional explanation, modes of transcriptional control over the gad system are rather complex. Transcriptional factors RpoS, cyclic AMP receptor protein, HN-S and EvgA all play a role in transcriptional regulation. Transcriptional regulators GadW and GadX also affect induction of the gad system through intricate interactions both with the GadA promoter region, as well as with one another. Due to this complexity, our strategy was to characterize the gadA promoter empirically.

Sequence and Features