Dynamic Na+/H+ exchanger 1 (NHE1) - calmodulin complexes of varying stoichiometry and structure regulate Ca2+-dependent NHE1 activation
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Dynamic Na+/H+ exchanger 1 (NHE1) - calmodulin complexes of varying stoichiometry and structure regulate Ca2+-dependent NHE1 activation. / Sjøgaard-Frich, Lise M.; Prestel, Andreas; Pedersen, Emilie S.; Severin, Marc; Kristensen, Kristian Kølby; Olsen, Johan G.; Kragelund, Birthe B.; Pedersen, Stine Falsig.
In: eLife, Vol. 10, e60889, 2021.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Dynamic Na+/H+ exchanger 1 (NHE1) - calmodulin complexes of varying stoichiometry and structure regulate Ca2+-dependent NHE1 activation
AU - Sjøgaard-Frich, Lise M.
AU - Prestel, Andreas
AU - Pedersen, Emilie S.
AU - Severin, Marc
AU - Kristensen, Kristian Kølby
AU - Olsen, Johan G.
AU - Kragelund, Birthe B.
AU - Pedersen, Stine Falsig
PY - 2021
Y1 - 2021
N2 - Calmodulin (CaM) engages in Ca2+-dependent interactions with numerous proteins, including a still incompletely understood physical and functional interaction with the human Na+/ H+-exchanger NHE1. Using nuclear magnetic resonance (NMR) spectroscopy, isothermal titration calorimetry, and fibroblasts stably expressing wildtype and mutant NHE1, we discovered multiple accessible states of this functionally important complex existing in different NHE1:CaM stoichiometries and structures. We determined the NMR solution structure of a ternary complex in which CaM links two NHE1 cytosolic tails. In vitro, stoichiometries and affinities could be tuned by variations in NHE1:CaM ratio and calcium ([Ca2+]) and by phosphorylation of S648 in the first CaM- binding α-helix. In cells, Ca2+-CaM-induced NHE1 activity was reduced by mimicking S648 phosphorylation and by mutation of the first CaM-binding α-helix, whereas it was unaffected by inhibition of Akt, one of several kinases phosphorylating S648. Our results demonstrate a diversity of NHE1:CaM interaction modes and suggest that CaM may contribute to NHE1 dimerization and thereby augment NHE1 regulation. We propose that a similar structural diversity is of relevance to many other CaM complexes.
AB - Calmodulin (CaM) engages in Ca2+-dependent interactions with numerous proteins, including a still incompletely understood physical and functional interaction with the human Na+/ H+-exchanger NHE1. Using nuclear magnetic resonance (NMR) spectroscopy, isothermal titration calorimetry, and fibroblasts stably expressing wildtype and mutant NHE1, we discovered multiple accessible states of this functionally important complex existing in different NHE1:CaM stoichiometries and structures. We determined the NMR solution structure of a ternary complex in which CaM links two NHE1 cytosolic tails. In vitro, stoichiometries and affinities could be tuned by variations in NHE1:CaM ratio and calcium ([Ca2+]) and by phosphorylation of S648 in the first CaM- binding α-helix. In cells, Ca2+-CaM-induced NHE1 activity was reduced by mimicking S648 phosphorylation and by mutation of the first CaM-binding α-helix, whereas it was unaffected by inhibition of Akt, one of several kinases phosphorylating S648. Our results demonstrate a diversity of NHE1:CaM interaction modes and suggest that CaM may contribute to NHE1 dimerization and thereby augment NHE1 regulation. We propose that a similar structural diversity is of relevance to many other CaM complexes.
U2 - 10.7554/eLife.60889
DO - 10.7554/eLife.60889
M3 - Journal article
C2 - 33655882
AN - SCOPUS:85103387207
VL - 10
JO - eLife
JF - eLife
SN - 2050-084X
M1 - e60889
ER -
ID: 260544977