3CLL

Crystal structure of the Spinach Aquaporin SoPIP2;1 S115E mutant


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.193 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.166 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Structural and functional analysis of SoPIP2;1 mutants adds insight into plant aquaporin gating.

Nyblom, M.Frick, A.Wang, Y.Ekvall, M.Hallgren, K.Hedfalk, K.Neutze, R.Tajkhorshid, E.Tornroth-Horsefield, S.

(2009) J Mol Biol 387: 653-668

  • DOI: https://doi.org/10.1016/j.jmb.2009.01.065
  • Primary Citation of Related Structures:  
    3CLL, 3CN5, 3CN6

  • PubMed Abstract: 

    Plant plasma membrane aquaporins facilitate water flux into and out of plant cells, thus coupling their cellular function to basic aspects of plant physiology. Posttranslational modifications of conserved phosphorylation sites, changes in cytoplasmic pH and the binding of Ca(2+) can regulate water transport activity by gating the plasma membrane aquaporins. A structural mechanism unifying these diverse biochemical signals has emerged for the spinach aquaporin SoPIP2;1, although several questions concerning the opening mechanism remain. Here, we describe the X-ray structures of the S115E and S274E single SoPIP2;1 mutants and the corresponding double mutant. Phosphorylation of these serines is believed to increase water transport activity of SoPIP2;1 by opening the channel. However, all mutants crystallised in a closed conformation, as confirmed by water transport assays, implying that neither substitution fully mimics the phosphorylated state. Nevertheless, a half-turn extension of transmembrane helix 1 occurs upon the substitution of Ser115, which draws the C(alpha) atom of Glu31 10 A away from its wild-type conformation, thereby disrupting the divalent cation binding site involved in the gating mechanism. Mutation of Ser274 disorders the C-terminus but no other significant conformational changes are observed. Inspection of the hydrogen-bond interactions within loop D suggested that the phosphorylation of Ser188 may also produce an open channel, and this was supported by an increased water transport activity for the S188E mutant and molecular dynamics simulations. These findings add additional insight into the general mechanism of plant aquaporin gating.


  • Organizational Affiliation

    Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Aquaporin300Spinacia oleraceaMutation(s): 1 
Membrane Entity: Yes 
UniProt
Find proteins for Q41372 (Spinacia oleracea)
Explore Q41372 
Go to UniProtKB:  Q41372
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ41372
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.193 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.166 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86.855α = 90
b = 86.855β = 90
c = 86.534γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-02-24
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-20
    Changes: Database references
  • Version 1.3: 2023-08-30
    Changes: Data collection, Refinement description