2abm
From Proteopedia
(New page: 200px<br /><applet load="2abm" size="450" color="white" frame="true" align="right" spinBox="true" caption="2abm, resolution 3.20Å" /> '''Crystal Structure of...) |
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| - | [[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size=" | + | [[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2abm, resolution 3.20Å" /> | caption="2abm, resolution 3.20Å" /> | ||
'''Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels'''<br /> | '''Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels'''<br /> | ||
==Overview== | ==Overview== | ||
| - | AqpZ is a homotetramer of four water-conducting channels that facilitate | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 2ABM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with BGL, PO4, POQ, PEE, 3PG and AGA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 2ABM is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=BGL:'>BGL</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=POQ:'>POQ</scene>, <scene name='pdbligand=PEE:'>PEE</scene>, <scene name='pdbligand=3PG:'>3PG</scene> and <scene name='pdbligand=AGA:'>AGA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2ABM OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Daniels, B | + | [[Category: Daniels, B V.]] |
[[Category: Fu, D.]] | [[Category: Fu, D.]] | ||
[[Category: Jiang, J.]] | [[Category: Jiang, J.]] | ||
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[[Category: membrane protein]] | [[Category: membrane protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:25:49 2008'' |
Revision as of 14:25, 21 February 2008
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Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels
Overview
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.
About this Structure
2ABM is a Single protein structure of sequence from Escherichia coli with , , , , and as ligands. 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 Thu Feb 21 16:25:49 2008
Categories: Escherichia coli | Single protein | Daniels, B V. | Fu, D. | Jiang, J. | 3PG | AGA | BGL | PEE | PO4 | POQ | Aquaporin | Membrane protein
