Chemotaxis feedback proteins

Chemotaxis feedback proteins alter the internal signalling state of a chemotactic cell in response to pathway activity. In the canonical Escherichia coli system, CheR adds receptor methyl groups and CheB removes them, with CheB activity coupled to phosphorylation. Their opposing actions help restore receptor-pathway output after a persistent stimulus. This changes response sensitivity while allowing continued detection of subsequent changes in attractant concentration. ^[ref]

CheW is a coupling protein linking chemotaxis receptor arrays to CheA-associated signalling complexes. Removing it from a reconstituted system can test its functional requirement, while a physical-interface assay addresses direct contacts.

CheA is the signaling enzyme that promotes phosphorylation of CheY and CheB in the chemotaxis feedback regulation pathway.

CheB is an enzyme that reverses receptor methylation in chemotaxis; its regulation contributes to negative feedback.

CheR is an enzyme that catalyzes receptor methylation in chemotaxis, contributing to signaling adaptation.

Its methyltransferase activity opposes receptor demethylation by CheB. Adjusting modification state changes receptor sensitivity after sustained stimulation, allowing a new stimulus change to remain detectable. ^[ref]

CheY is a bacterial response-regulator protein whose phosphorylation state couples receptor-pathway activity to bacterial flagellar motor behaviour. In Escherichia coli, CheA transfers phosphate to CheY, and phosphorylated CheY interacts with the motor switch, including FliM. CheZ accelerates signal removal through dephosphorylation. Production and removal therefore jointly control motor bias, allowing a biochemical pathway to regulate swimming without the motor directly sensing external attractant. ^[ref]

CheZ is an enzyme that binds phosphorylated CheY and accelerates removal of its phosphate.

Accelerated dephosphorylation shortens the lifetime of the motor-regulating CheY signal. The output depends on both phosphorylation and removal, so equal kinase activity can produce different steady signalling when CheZ activity changes. ^[ref]