CheBP

CheBP is an abbreviation used in some scientific literature to denote the phosphorylated form of the chemotaxis response regulator CheB, commonly written CheB-P. The usage is not standardized across all sources, and some texts simply refer to CheB-P, while others use CheBP to emphasize the phosphorylation state.

In the bacterial chemotaxis signaling pathway, CheB is a two-domain response regulator that modulates receptor activity through demethylation. Its activity is increased when it is phosphorylated on a conserved aspartate residue by the histidine kinase CheA. Phosphorylated CheB (CheB-P) demethylates methylated sites on methyl-accepting chemotaxis proteins (MCPs), thereby altering receptor sensitivity and contributing to adaptation to persistent stimuli. CheB-P operates in balance with CheR, which methylates MCPs; together these enzymes tune the signaling output to maintain appropriate chemotactic responsiveness.

Structure and regulation: CheB typically contains an N-terminal receiver domain that accepts phosphate and a C-terminal methylesterase domain that carries out demethylation. Phosphorylation of the receiver domain enhances the catalytic activity of the methylesterase domain, and dephosphorylation reduces activity, allowing rapid reversible control of adaptation.

Distribution: CheB-family proteins with CheB-like receiver and methylesterase domains are found across many bacteria possessing chemotaxis systems. The term CheBP is most common in older literature or in organism-specific contexts; contemporary annotations often use CheB-P to denote the phosphorylated form.

See also: CheA, CheY, CheR, MCPs, bacterial chemotaxis, two-component signaling systems.