High zinc sensitivity and pore formation in an invertebrate P2X receptor.
To investigate fast purinergic signaling in invertebrates, we examined the functional properties of a P2X receptor subunit cloned from the parasitic platyhelminth Schistosoma mansoni. This purinoceptor (SmP2X) displays unambiguous homology of primary sequence with vertebrate P2X subunits. SmP2X subunits assemble into homomeric ATP-gated channels that exhibit slow activation kinetics and are blocked by suramin and PPADS but not TNP-ATP. SmP2X mediates the uptake of the dye YO-PRO-1 through the formation of large pores and can be blocked by submicromolar concentrations of extracellular Zn2+ ions (IC50 = 0.4 microM). The unique receptor phenotype defined by SmP2X suggests that slow kinetics, modulation by zinc and the ability to form large pores are ancestral properties of P2X receptors. The high sensitivity of SmP2X to zinc further reveals a zinc regulation requirement for the parasite's physiology that could potentially be exploited for therapeutic purposes.
Raouf
Ramin
R
Montreal Neurological Institute, Dept. Neurology and Neurosurgery, McGill University, 3801 University, Montreal, Que., Canada H3A 2B4.
Blais
Dominique
D
Séguéla
Philippe
P
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D007700:Kinetics; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058469:Receptors, Purinergic P2X; D012550:Schistosoma mansoni / Q000378:metabolism; D014981:Xenopus; D015032:Zinc / Q000378:metabolism*
D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D000255:Adenosine Triphosphate; D015032:Zinc