TY - JOUR
T1 - SLO2 Channels are inhibited by all divalent cations that activate SLO1 K- channels
AU - Budelli, Gonzalo
AU - Sun, Qi
AU - Ferreira, Juan
AU - Butler, Alice
AU - Santi, Celia M.
AU - Salkoff, Lawrence
N1 - Publisher Copyright:
©2016 by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - Two members of the family of high conductance K+ channels SLO1 and SLO2 are both activated by intracellular cations. However, SLO1 is activated by Ca2+ and other divalent cations, while SLO2 (Slack or SLO2.2 from rat) is activated by Na+ . Curiously though, we found that SLO2.2 is inhibited by all divalent cations that activate SLO1, with Zn2+ being the most effective inhibitor with an IC50 of 8 μM in contrast to Mg2+, the least effective, with an IC50 of 1.5 mM. Our results suggest that divalent cations are not SLO2 pore blockers, but rather inhibit channel activity by an allosteric modification of channel gating. By site-directed mutagenesis we show that a histidine residue (His-347) downstream of S6 reduces inhibition by divalent cations. An analogous His residue present in someCNGchannels is an inhibitory cation binding site. To investigate whether inhibition by divalent cations is conserved in an invertebrate SLO2 channel we cloned the SLO2 channel from Drosophila (dSLO2) and compared its properties to those of rat SLO2.2. We found that, like rat SLO2.2, dSLO2 was also activated by Na+ and inhibited by divalent cations. Inhibition of SLO2 channels in mammals and Drosophila by divalent cations that have second messenger functions may reflect the physiological regulation of these channels by one or more of these ions.A.
AB - Two members of the family of high conductance K+ channels SLO1 and SLO2 are both activated by intracellular cations. However, SLO1 is activated by Ca2+ and other divalent cations, while SLO2 (Slack or SLO2.2 from rat) is activated by Na+ . Curiously though, we found that SLO2.2 is inhibited by all divalent cations that activate SLO1, with Zn2+ being the most effective inhibitor with an IC50 of 8 μM in contrast to Mg2+, the least effective, with an IC50 of 1.5 mM. Our results suggest that divalent cations are not SLO2 pore blockers, but rather inhibit channel activity by an allosteric modification of channel gating. By site-directed mutagenesis we show that a histidine residue (His-347) downstream of S6 reduces inhibition by divalent cations. An analogous His residue present in someCNGchannels is an inhibitory cation binding site. To investigate whether inhibition by divalent cations is conserved in an invertebrate SLO2 channel we cloned the SLO2 channel from Drosophila (dSLO2) and compared its properties to those of rat SLO2.2. We found that, like rat SLO2.2, dSLO2 was also activated by Na+ and inhibited by divalent cations. Inhibition of SLO2 channels in mammals and Drosophila by divalent cations that have second messenger functions may reflect the physiological regulation of these channels by one or more of these ions.A.
UR - http://www.scopus.com/inward/record.url?scp=84965131365&partnerID=8YFLogxK
U2 - 10.1074/jbc.M115.709436
DO - 10.1074/jbc.M115.709436
M3 - Article
C2 - 26823461
AN - SCOPUS:84965131365
SN - 0021-9258
VL - 291
SP - 7347
EP - 7356
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 14
ER -