2npd: Difference between revisions

Revision as of 19:09, 21 February 2008

An unusual twin-His arrangement in the pore of ammonia channels is essential for substrate conductance

OverviewOverview

Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine.

About this StructureAbout this Structure

2NPD is a Single protein structure of sequence from Escherichia coli with and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

An unusual twin-his arrangement in the pore of ammonia channels is essential for substrate conductance., Javelle A, Lupo D, Zheng L, Li XD, Winkler FK, Merrick M, J Biol Chem. 2006 Dec 22;281(51):39492-8. Epub 2006 Oct 12. PMID:17040913

Page seeded by OCA on Thu Feb 21 18:09:24 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

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-[[Image:2npd.gif|left|200px]]<br /><applet load="2npd" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:2npd.gif|left|200px]]<br /><applet load="2npd" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="2npd, resolution 2.10&Aring;" />
 '''An unusual twin-His arrangement in the pore of ammonia channels is essential for substrate conductance'''<br />
 ==Overview==
-Amt proteins constitute a class of ubiquitous integral membrane proteins, that mediate movement of ammonium across cell membranes. They are, homotrimers, in which each subunit contains a narrow pore through which, substrate transport occurs. Two conserved histidine residues in the pore, have been proposed to be necessary for ammonia conductance. By analyzing, 14 engineered polar and non-polar variants of these histidines, in, Escherichia coli AmtB, we show that both histidines are absolutely, required for optimum substrate conductance. Crystal structures of variants, confirm that substitution of the histidine residues does not affect AmtB, structure. In a subgroup of Amt proteins, found only in fungi, one of the, histidines is replaced by glutamate. The equivalent substitution in E., coli AmtB is partially active, and the structure of this variant suggests, that the glutamate side chain can make similar interactions to those made, by histidine.
+Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine.
 ==About this Structure==
-NPD 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 ACT and IMD as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2NPD OCA].
+NPD 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=ACT:'>ACT</scene> and <scene name='pdbligand=IMD:'>IMD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2NPD OCA].
 ==Reference==
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 [[Category: Single protein]]
 [[Category: Lupo, D.]]
-[[Category: Winkler, F.K.]]
+[[Category: Winkler, F K.]]
 [[Category: ACT]]
 [[Category: IMD]]
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 [[Category: membrane protein]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 12:49:56 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:09:24 2008''