TY - JOUR
T1 - Functional characterization of a potassium-selective prokaryotic glutamate receptor
AU - Chen, Guo Qiang
AU - Cul, Changhal
AU - Mayer, Mark L.
AU - Gouaux, Eric
PY - 1999/12/16
Y1 - 1999/12/16
N2 - Ion channels are molecular pores that facilitate the passage of ions across cell membranes and participate in a range of biological processes, from excitatory signal transmission in the mammalian nervous system to the modulation of swimming behaviour in the protozoan Paramecium. Two particularly important families of ion channels are ionotropic glutamate receptors (GluRs) and potassium channels. GluRs are permeable to Na+, K+ and Ca2+, are gated by glutamate, and have previously been found only in eukaryotes. In contrast, potassium channels are selective for K+, are gated by a range of stimuli, and are found in both prokaryotes and eukaryotes. Here we report the discovery and functional characterization of GluR0 from Synechocystis PCC 6803, which is the first GluR found in a prokaryote. GluR0 binds glutamate, forms potassium-selective channels and is related in amino- acid sequence to both eukaryotic GluRs and potassium channels. On the basis of amino-acid sequence and functional relationships between GluR0 and eukaryotic GluRs, we propose that a prokaryotic GluR was the precursor to eukaryotic GluRs. GluR0 provides evidence for the missing link between potassium channels and GluRs, and we suggest that their ion channels have a similar architecture, that GluRs are tetramers and that the gating mechanisms of GluRs and potassium channels have some essential-features in common.
AB - Ion channels are molecular pores that facilitate the passage of ions across cell membranes and participate in a range of biological processes, from excitatory signal transmission in the mammalian nervous system to the modulation of swimming behaviour in the protozoan Paramecium. Two particularly important families of ion channels are ionotropic glutamate receptors (GluRs) and potassium channels. GluRs are permeable to Na+, K+ and Ca2+, are gated by glutamate, and have previously been found only in eukaryotes. In contrast, potassium channels are selective for K+, are gated by a range of stimuli, and are found in both prokaryotes and eukaryotes. Here we report the discovery and functional characterization of GluR0 from Synechocystis PCC 6803, which is the first GluR found in a prokaryote. GluR0 binds glutamate, forms potassium-selective channels and is related in amino- acid sequence to both eukaryotic GluRs and potassium channels. On the basis of amino-acid sequence and functional relationships between GluR0 and eukaryotic GluRs, we propose that a prokaryotic GluR was the precursor to eukaryotic GluRs. GluR0 provides evidence for the missing link between potassium channels and GluRs, and we suggest that their ion channels have a similar architecture, that GluRs are tetramers and that the gating mechanisms of GluRs and potassium channels have some essential-features in common.
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U2 - 10.1038/45568
DO - 10.1038/45568
M3 - Article
C2 - 10617203
AN - SCOPUS:0033576612
SN - 0028-0836
VL - 402
SP - 817
EP - 821
JO - Nature
JF - Nature
IS - 6763
ER -