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2abm

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{{STRUCTURE_2abm| PDB=2abm | SCENE= }}
{{STRUCTURE_2abm| PDB=2abm | SCENE= }}
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'''Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels'''
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===Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels===
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==Overview==
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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.
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{{ABSTRACT_PUBMED_16239219}}
==About this Structure==
==About this Structure==
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[[Category: Aquaporin]]
[[Category: Aquaporin]]
[[Category: Membrane protein]]
[[Category: Membrane protein]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 18:51:15 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 02:27:05 2008''

Revision as of 23:27, 27 July 2008

Image:2abm.png

Template:STRUCTURE 2abm

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

Template:ABSTRACT PUBMED 16239219

About this Structure

2ABM is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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 BV, Fu D, J Biol Chem. 2006 Jan 6;281(1):454-60. Epub 2005 Oct 20. PMID:16239219

Page seeded by OCA on Mon Jul 28 02:27:05 2008

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