2abm: Difference between revisions

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[[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size="350" color="white" frame="true" align="right" spinBox="true"

caption="2abm, resolution 3.20Å" />

'''Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels'''<br />

==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.

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 [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://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=2ABM OCA].

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==

Line 13:

[[Category: Escherichia coli]]

[[Category: Single protein]]

[[Category: Daniels, B.V.]]

[[Category: Daniels, B V.]]

[[Category: Fu, D.]]

[[Category: Jiang, J.]]

Line 25:

[[Category: membrane protein]]

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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:25:49 2008''

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@@ Line 1: / Line 1: @@
-[[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:2abm.gif|left|200px]]<br /><applet load="2abm" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="2abm, resolution 3.20&Aring;" />
 '''Crystal Structure of Aquaporin Z Tetramer Reveals both Open and Closed Water-conducting Channels'''<br />
 ==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.
+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==
-ABM 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://ispc.weizmann.ac.il/oca-bin/ocashort?id=2ABM OCA].
+ABM 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==
@@ Line 13: / Line 13: @@
 [[Category: Escherichia coli]]
 [[Category: Single protein]]
-[[Category: Daniels, B.V.]]
+[[Category: Daniels, B V.]]
 [[Category: Fu, D.]]
 [[Category: Jiang, J.]]
@@ Line 25: / Line 25: @@
 [[Category: membrane protein]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 08:02:20 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:25:49 2008''