2ABM

Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.186 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history. 

Literature

Crystal Structure of AqpZ Tetramer Reveals Two Distinct Arg-189 Conformations Associated with Water Permeation through the Narrowest Constriction of the Water-conducting Channel.

Jiang, J., Daniels, B.V., Fu, D.

(2006) J.Biol.Chem. 281: 454-460

  • DOI: 10.1074/jbc.M508926200

  • PubMed Abstract: 

    • AqpZ is a homotetramer of four water-conducting channels that facilitate rapid water movements across the plasma membrane of Escherichia coli. Here we report a 3.2 angstroms crystal structure of the tetrameric AqpZ (tAqpZ). All channel-lining residue ...

    AqpZ is a homotetramer of four water-conducting channels that facilitate rapid water movements across the plasma membrane of Escherichia coli. Here we report a 3.2 angstroms crystal structure of the tetrameric AqpZ (tAqpZ). All channel-lining residues in the four monomeric channels are found orientated in nearly identical positions with one marked exception at the narrowest channel constriction, where the side chain of a highly conserved Arg-189 adopts two distinct conformational orientations. In one of the four monomers, the guanidino group of Arg-189 points toward the periplasmic vestibule, opening up the constriction to accommodate the binding of a water molecule through a tridentate H-bond. In the other three monomers, the Arg-189 guanidino group bends over to form an H-bond with carbonyl oxygen of the Thr-183, thus occluding the channel. Therefore, the tAqpZ structure reveals two distinct Arg-189 confirmations associated with water permeation through the channel constrictions. Alternation between the two Arg-189 conformations disrupts continuous flow of water, thus regulating the open probability of the water pore. Further, the difference in Arg-189 displacements is correlated with a strong electron density found between the first transmembrane helices of two open channels, suggesting that the observed Arg-189 conformations are stabilized by asymmetrical subunit interactions in tAqpZ.

    Organizational Affiliation: 

    Department of Biology, Brookhaven National Laboratory, Upton, New York 11973, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Aquaporin Z
A, B, C, D, E, F, G, H
231Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: aqpZ (bniP)
Membrane protein
mpstruct		Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL		Sub Group: 
Channels: Aquaporins and Glyceroporins		Protein: 
AqpZ aquaporin water channel
Find proteins for P60844 (Escherichia coli (strain K12))
Go to UniProtKB:  P60844
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4
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B, C, F, G
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
BGL
Query on BGL
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A, B, E
B-2-OCTYLGLUCOSIDE
C14 H28 O6
BVHPDIWLWHHJPD-RKQHYHRCSA-N
 Ligand Interaction
AGA
Query on AGA
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C, G
(1S)-2-{[{[(2S)-2,3-DIHYDROXYPROPYL]OXY}(HYDROXY)PHOSPHORYL]OXY}-1-[(PENTANOYLOXY)METHYL]ETHYL OCTANOATE
PHOSPHATIDYL GLYCEROL
C19 H36 O10 P
UQSXQYRZHMGKIE-DLBZAZTESA-M
 Ligand Interaction
POQ
Query on POQ
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A
BIS(((3S,4S,5R,6R)-5-(ETHYL(PHOSPHORYLOXY))-3,4,6-TRIHYDROXY-TETRAHYDRO-2H-PYRAN-2-YL)METHYL) HYDROGEN PHOSPHATE
C16 H33 O20 P3
QTCHWELPTUAUQX-ASCZGESISA-N
 Ligand Interaction
3PG
Query on 3PG
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C, G
3-PHOSPHOGLYCERIC ACID
C3 H7 O7 P
OSJPPGNTCRNQQC-UWTATZPHSA-N
 Ligand Interaction
PEE
Query on PEE
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A, B, E, F, G
1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine
DOPE
C41 H83 N O8 P
LVNGJLRDBYCPGB-LDLOPFEMSA-O
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.186 
  • Space Group: P 41 2 2
Unit Cell:
Length (Å)Angle (°)
a = 119.152α = 90.00
b = 119.152β = 90.00
c = 380.394γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
CNSphasing
SCALEPACKdata scaling
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-09-20
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2014-10-29
    Type: Non-polymer description