TY - JOUR
T1 - Tuning the ion selectivity of two-pore channels
AU - Guo, Jiangtao
AU - Zeng, Weizhong
AU - Jiang, Youxing
N1 - Funding Information:
The Argonne National Laboratory is operated by UChicago Argonne, LLC, for the US Department of Energy, Office of Biological and Environmental Research under Contract DEAC02-06CH11357. The Berkeley Center for Structural Biology is supported, in part, by the NIH, National Institute of General Medical Sciences, and Howard Hughes Medical Institute. The ALS is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract DE-AC02-05CH11231. This work was supported, in part, by the Howard Hughes Medical Institute and by grants from the NIH (Grant GM079179 to Y.J.) and the Welch Foundation (Grant I-1578 to Y.J.).
PY - 2017/1/31
Y1 - 2017/1/31
N2 - Organellar two-pore channels (TPCs) contain two copies of a Shakerlike six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in plants and animals. Interestingly, plant and animal TPCs share high sequence similarity in the filter region, yet exhibit drastically different ion selectivity. Plant TPC1 functions as a nonselective cation channel on the vacuole membrane, whereas mammalian TPC channels have been shown to be endo/lysosomal Na+-selective or Ca2+-release channels. In this study, we performed systematic characterization of the ion selectivity of TPC1 from Arabidopsis thaliana (AtTPC1) and compared its selectivity with the selectivity of human TPC2 (HsTPC2). We demonstrate that AtTPC1 is selective for Ca2+ over Na+, but nonselective among monovalent cations (Li+, Na+, and K+). Our results also confirm that HsTPC2 is a Na+-selective channel activated by phosphatidylinositol 3,5-bisphosphate. Guided by our recent structure of AtTPC1, we converted AtTPC1 to a Na+-selective channel by mimicking the selectivity filter of HsTPC2 and identified key residues in the TPC filters that differentiate the selectivity between AtTPC1 and HsTPC2. Furthermore, the structure of the Na+-selective AtTPC1 mutant elucidates the structural basis for Na+ selectivity in mammalian TPCs.
AB - Organellar two-pore channels (TPCs) contain two copies of a Shakerlike six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in plants and animals. Interestingly, plant and animal TPCs share high sequence similarity in the filter region, yet exhibit drastically different ion selectivity. Plant TPC1 functions as a nonselective cation channel on the vacuole membrane, whereas mammalian TPC channels have been shown to be endo/lysosomal Na+-selective or Ca2+-release channels. In this study, we performed systematic characterization of the ion selectivity of TPC1 from Arabidopsis thaliana (AtTPC1) and compared its selectivity with the selectivity of human TPC2 (HsTPC2). We demonstrate that AtTPC1 is selective for Ca2+ over Na+, but nonselective among monovalent cations (Li+, Na+, and K+). Our results also confirm that HsTPC2 is a Na+-selective channel activated by phosphatidylinositol 3,5-bisphosphate. Guided by our recent structure of AtTPC1, we converted AtTPC1 to a Na+-selective channel by mimicking the selectivity filter of HsTPC2 and identified key residues in the TPC filters that differentiate the selectivity between AtTPC1 and HsTPC2. Furthermore, the structure of the Na+-selective AtTPC1 mutant elucidates the structural basis for Na+ selectivity in mammalian TPCs.
KW - Crystal structure
KW - Ion selectivity
KW - Two-pore channel
UR - http://www.scopus.com/inward/record.url?scp=85011260719&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85011260719&partnerID=8YFLogxK
U2 - 10.1073/pnas.1616191114
DO - 10.1073/pnas.1616191114
M3 - Article
C2 - 28096396
AN - SCOPUS:85011260719
SN - 0027-8424
VL - 114
SP - 1009
EP - 1014
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 5
ER -