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Abstract
Leaf Na+ exclusion, mediated by plasma membrane-localised Class 1 High-affinity potassium (K+) Transporters (HKTs), is a key mechanism contributing to salinity tolerance of several major crop plants. We determined previously that the leucine to proline residue substitution at position 189 (L189P) in barley HvHKT1;5 disrupts its characteristic plasma membrane localisation and Na+ conductance. Here, we focus on a surprising observation that a single residue deletion of methionine at position 372 (M372del) within the conserved VMMYL motif in plant HKTs, restores plasma membrane localisation but not Na+ conductance in HvHKT1;5 P189. To clarify why the singular M372 deletion regains plasma membrane localisation, we built 3D models and defined α-helical assembly pathways of the P189 M372del mutant, and compared these findings to the wild-type protein, and the HvHKT1;5 L189 variant and its M372del mutant. We find that α-helical association and assembly pathways in HvHKT1;5 proteins fall in two contrasting categories. Inspections of structural flexibility through molecular dynamics simulations revealed that the conformational states of HvHKT1;5 P189 diverge from those of the L189 variant and M372del mutants. We propose that M372del in HvHKT1;5 P189 instigates structural rearrangements allowing routing to the plasma membrane, while the restoration of conductance would require further interventions. We integrate the microscopy, electrophysiology, and biocomputational data and discuss how a profound structural change in HvHKT1;5 P189 M372del impacts its α-helical protein association pathway and flexibility, and how these features underlie a delicate balance leading to restoring plasma membrane localisation but not Na+ conductance.
Original language | English |
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Article number | 183669 |
Number of pages | 11 |
Journal | BBA - Biomembranes |
Volume | 1863 |
Issue number | 10 |
Early online date | 15 Jun 2021 |
DOIs | |
Publication status | Published - 1 Oct 2021 |
Keywords
- 3D protein modelling
- Confocal microscopy
- Molecular dynamics simulations
- Salinity
- Two-Electrode Voltage-Clamp
- α-Helical association and assembly pathways
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Cell Biology
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Dive into the research topics of 'A single residue deletion in the barley HKT1;5 P189 variant restores plasma membrane localisation but not Na+ conductance'. Together they form a unique fingerprint.Projects
- 1 Finished
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Exploiting Synergies in Barley Research (Partnering Award)
Brown, J. (Investigator), Halpin, C. (Investigator) & Waugh, R. (Investigator)
Biotechnology and Biological Sciences Research Council
26/06/14 → 25/12/18
Project: Research