methyl accepting chemotaxis protein complex

Definition

Target type: cellularcomponent

A transmembrane protein complex that consists of multiple methyl-accepting chemoreceptor protein subunits, a histidine kinase and a connector protein and which functions in the regulation of flagellar rotary motor activity in response to an external chemical stimulus. [GOC:dos, PMID:1326408, PMID:15802240]

The methyl-accepting chemotaxis protein (MCP) complex is a transmembrane signaling complex found in bacteria that plays a crucial role in chemotaxis, the directed movement of bacteria towards attractants and away from repellants. The complex is composed of multiple protein subunits, including:

1. **MCPs (Methyl-accepting Chemotaxis Proteins):** These are the sensory receptors that bind to attractants or repellants in the environment. They are transmembrane proteins with a periplasmic domain that binds the ligand and a cytoplasmic domain that interacts with the CheA histidine kinase.
2. **CheA (Histidine Kinase):** This protein is located in the cytoplasm and phosphorylates itself on a histidine residue in response to changes in the conformation of the MCPs.
3. **CheW (Coupling Protein):** CheW is a small protein that acts as a linker between the MCPs and CheA. It helps to facilitate the transfer of information from the MCPs to CheA.
4. **CheY (Response Regulator):** CheY is also a cytoplasmic protein that is phosphorylated by CheA. Phosphorylated CheY interacts with the flagellar motor, causing a change in the direction of rotation of the flagella. This change in flagellar rotation is responsible for the directed movement of the bacterium.

The MCP complex is assembled in the bacterial membrane. Each MCP subunit is a trimer, and multiple trimers can associate to form larger oligomers. The organization of the MCPs in the complex is important for its function. The arrangement of the MCPs allows for cooperative binding of ligands, which amplifies the signal. The complex also exhibits a mechanism of adaptation, which allows the bacteria to reset their response after prolonged exposure to a stimulus. This is achieved by methylation of the MCPs, which counteracts the phosphorylation of CheA.

The methylation and demethylation of the MCPs is controlled by the proteins CheR and CheB, respectively. CheR is a methyltransferase that adds methyl groups to specific glutamate residues on the MCPs, while CheB is a methylesterase that removes methyl groups. The balance between methylation and demethylation determines the sensitivity of the MCP complex to stimuli.

In summary, the MCP complex is a sophisticated signaling system that enables bacteria to sense and respond to environmental cues. The complex is highly regulated and exhibits a dynamic interplay between phosphorylation, methylation, and demethylation, allowing bacteria to adapt and navigate their environment.'
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Proteins (1)

Compounds (1)