TY - JOUR TI - Cryo-EM structures of an LRRC8 chimera with native functional properties reveal heptameric assembly AU - Takahashi, Hirohide AU - Yamada, Toshiki AU - Denton, Jerod S AU - Strange, Kevin AU - Karakas, Erkan A2 - Maduke, Merritt A2 - Aldrich, Richard W VL - 12 PY - 2023 DA - 2023/03/10 SP - e82431 C1 - eLife 2023;12:e82431 DO - 10.7554/eLife.82431 UR - https://doi.org/10.7554/eLife.82431 AB - Volume-regulated anion channels (VRACs) mediate volume regulatory Cl- and organic solute efflux from vertebrate cells. VRACs are heteromeric assemblies of LRRC8A-E proteins with unknown stoichiometries. Homomeric LRRC8A and LRRC8D channels have a small pore, hexameric structure. However, these channels are either non-functional or exhibit abnormal regulation and pharmacology, limiting their utility for structure-function analyses. We circumvented these limitations by developing novel homomeric LRRC8 chimeric channels with functional properties consistent with those of native VRAC/LRRC8 channels. We demonstrate here that the LRRC8C-LRRC8A(IL125) chimera comprising LRRC8C and 25 amino acids unique to the first intracellular loop (IL1) of LRRC8A has a heptameric structure like that of homologous pannexin channels. Unlike homomeric LRRC8A and LRRC8D channels, heptameric LRRC8C-LRRC8A(IL125) channels have a large-diameter pore similar to that estimated for native VRACs, exhibit normal DCPIB pharmacology, and have higher permeability to large organic anions. Lipid-like densities are located between LRRC8C-LRRC8A(IL125) subunits and occlude the channel pore. Our findings provide new insights into VRAC/LRRC8 channel structure and suggest that lipids may play important roles in channel gating and regulation. KW - cryo-EM KW - VRAC KW - LRRC8C KW - LRRC8A KW - chimera KW - ion channel JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -