INVESTIGADORES
SPITZMAUL Guillermo Federico
artículos
Título:
Molecular Mechanisms and Binding Site Location for the Noncompetitive Antagonist Crystal Violet on Nicotinic Acetylcholine Receptors
Autor/es:
ARIAS, HUGO R; BHUMIREDDY, PANKAJ; SPITZMAUL, GUILLERMO; TRUDELL, JAMES R.; BOUZAT, CECILIA
Revista:
BIOCHEMISTRY
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2006 vol. 45 p. 2014 - 2026
ISSN:
0006-2960
Resumen:
We investigated the molecular mechanisms and
the binding site location for the fluorophor crystal violet (CrV), a
noncompetitive antagonist of the nicotinic acetylcholine receptor (AChR). To
this end, radiolabeled competition binding, fluorescence spectroscopy,
Schild-type analysis, patch-clamp recordings, and molecular dynamics approaches
were used. The results indicate that: (1) CrV interacts with the
desensitized Torpedo AChR with higher affinity than the resting state at
several temperatures (5-37° C); (2) CrV-induced
inhibition of the phencyclidine (PCP) analog [3H]thienylcyclohexylpiperidine
binding to the desensitized or resting AChR, probably by a steric mechanism; (3)
tetracaine inhibits CrV binding to the resting AChR, probably by a steric
mechanism; (4) barbiturates modulate CrV binding to the resting AChR by
an allosteric mechanism; (5) CrV itself induces AChR desensitization; (6)
CrV decreases the peak of macroscopic currents by acting on the resting AChR,
but without affecting the desensitization rate from the open state; and (7)
two tertiary amino groups from CrV may bind to the alpha1-Glu262
residues (located at position 20) in the resting state. We conclude that the
CrV binding site partially overlaps the PCP locus in the resting and
desensitized state. We conclude that the CrV binding site overlaps the PCP
locus in the resting and desensitized state. The noncompetitive action of CrV
may be explained by an allosteric mechanism in which the binding of CrV to the
extracellular mouth of the resting receptor leads to an inhibition of channel
opening. Binding of CrV probably increases desensitization of the resting
channel and stabilizes the desensitized state.