Rotación CAR Rotación AR QUIMIOTAXIS Movimiento hacia un atrayente químico y desde un repelente químico.

Presentación del tema: "Rotación CAR Rotación AR QUIMIOTAXIS Movimiento hacia un atrayente químico y desde un repelente químico."— Transcripción de la presentación:

1 Rotación CAR Rotación AR QUIMIOTAXIS Movimiento hacia un atrayente químico y desde un repelente químico.

2 PROTEÍNAS DEL PROCESO DE QUIMIOTAXIS CheA: Regulador central - proteínquinasa que se autofosforila y CheY CheY-P CheB CheB-P CheW: acoplamiento de CheA al dominio citoplasmático del MCP CheY: en la forma CheY-P aumenta la probabilidad de inversión del giro CAR/AR CheZ: desfosforila CheY-P CheR: metiltransferasa. Metilación del dominio citoplasmático del MCP CheB: metilesterasa, CheB-P desmetila el dominio citoplasmático del MCP MCP: PROTEINAS ACEPTORAS DE METILOS (transductores)

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4 The chemotactic movement toward attractants is achieved by an adaptation mechanism that involves the methyltransferase CheR and the methylesterase CheB. CheR transfers methyl groups from S-adenosylmethionine to four to six glutamate residues in the MCP, and CheB, after its phosphorylation by CheA, removes these methyl groups. In the absence of chemotactic stimuli MCPs are continuously methylated and demethylated, leading to a basal level of receptor methylation that maintains an intermediate run-tumble behavior. Binding of an attractant to an MCP leads to inhibition of CheA activity and a drop in the CheB-P levels, causing increased methylation of the receptor by CheR that counteracts the attractant-dependent inhibition of CheA activity. The net consequence of this pathway is an adaptation of the receptor, resulting in a return of its signaling state to prestimulus levels. In this way a continuous sensing of concentration gradients of attractants is possible, and the periodical running induced by dephosphorylated CheA (and CheY) leads to a net movement toward the source of attractant.