The intracellular lipid-binding domain of human Na+/H+ exchanger 1 forms a lipid-protein co-structure essential for activity

The intracellular lipid-binding domain of human Na+/H+ exchanger 1 forms a lipid-protein co-structure essential for activity

Dynamic interactions of proteins with lipid membranes are essential regulatory events in biology, but remain rudimentarily understood and particularly overlooked in membrane proteins. The ubiquitously expressed membrane protein Na + /H + -exchanger 1 (NHE1) regulates intracellular pH (pH i ) with dy...

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Published in:Communications biology Vol. 3; no. 1; p. 731
Main Authors: Hendus-Altenburger, Ruth, Vogensen, Jens, Pedersen, Emilie Skotte, Luchini, Alessandra, Araya-Secchi, Raul, Bendsoe, Anne H., Prasad, Nanditha Shyam, Prestel, Andreas, Cardenas, Marité, Pedraz-Cuesta, Elena, Arleth, Lise, Pedersen, Stine F., Kragelund, Birthe B.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 03-12-2020
Nature Publishing Group
Subjects:
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13/1
14/63
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631/535
631/57
631/80
82/83
Animals
Biology
Biomedical and Life Sciences
Biotinylation
Cardiovascular diseases
CHO Cells
Circular Dichroism
Cricetinae
Cricetulus
Electrostatic properties
Humans
Hydrogen
Hydrophobicity
Immunofluorescence
Intracellular
Life Sciences
Lipid membranes
Lipids
Lipids - chemistry
Membrane proteins
Molecular modelling
Na+/H+-exchanging ATPase
Protein Binding
Protein Conformation
Protein Domains
Protein structure
Proteins
Sodium-Hydrogen Exchanger 1 - chemistry
Sodium-Hydrogen Exchanger 1 - metabolism
Structure-function relationships
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Summary:Dynamic interactions of proteins with lipid membranes are essential regulatory events in biology, but remain rudimentarily understood and particularly overlooked in membrane proteins. The ubiquitously expressed membrane protein Na + /H + -exchanger 1 (NHE1) regulates intracellular pH (pH i ) with dysregulation linked to e.g. cancer and cardiovascular diseases. NHE1 has a long, regulatory cytosolic domain carrying a membrane-proximal region described as a lipid-interacting domain (LID), yet, the LID structure and underlying molecular mechanisms are unknown. Here we decompose these, combining structural and biophysical methods, molecular dynamics simulations, cellular biotinylation- and immunofluorescence analysis and exchanger activity assays. We find that the NHE1-LID is intrinsically disordered and, in presence of membrane mimetics, forms a helical αα-hairpin co-structure with the membrane, anchoring the regulatory domain vis-a-vis the transport domain. This co-structure is fundamental for NHE1 activity, as its disintegration reduced steady-state pH i and the rate of pH i recovery after acid loading. We propose that regulatory lipid-protein co-structures may play equally important roles in other membrane proteins. Hendus-Altenburger et al. provide biochemical, structural and functional information on the lipid interaction domain (LID) of the Na+/H+ Exchanger 1 (NHE1). They find that NHE1-LID is intrinsically disordered, but, when allowed to interact with a lipid membrane, forms a helical αα-hairpin, stabilized by hydrophobic and electrostatic interactions. This co-structure is fundamental for NHE1 activity, giving insight into membrane protein regulation via disordered domains.
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ISSN:2399-3642
2399-3642
DOI:10.1038/s42003-020-01455-6