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Team:INSA-Lyon/Project/Stage3/Theory/ompR
From 2010.igem.org
ompR
The OmpR protein, in special osmolarity conditions detected by the captor EnvZ, is phosphoryled. This phosphorylation facilitates its DNA binding on the csgD promoter to activate the CsgD protein synthesis. But, in wild-type classical laboratory strains of E.coli K12, curli, a particular class of envelope organelles, are not synthesized at a level sufficient to allow adherence.
When these strains are maintained in continuous culture for long-term experiences or industrial processes, adherent mutant cells are generated. A regulatory mutation is necessary to activate curli expression and gain adherence. This point mutation affects the regulatory properties of the OmpR protein and causes overproduction of curli. This mutation results in the replacement of a leucine by an arginine residue at position 43 due to the replacement of a T base by an G one at position 234.
It seems that the point mutation on OmpR234 protein facilitate phosphorylation and consequently its DNA binding. Therefore, the CsgD protein synthesis is increased and consequently it increases the expression of the csgB and csgA genes and so the production of curli.
