View source for 4jre


==Crystal structure of nitrate/nitrite exchanger NarK with nitrite bound==
<StructureSection load='4jre' size='340' side='right'caption='[[4jre]], [[Resolution|resolution]] 2.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4jre]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4JRE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4JRE FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GYP:METHYL-ALPHA-D-GLUCOPYRANOSIDE'>GYP</scene>, <scene name='pdbligand=NO2:NITRITE+ION'>NO2</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4jre FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4jre OCA], [https://pdbe.org/4jre PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4jre RCSB], [https://www.ebi.ac.uk/pdbsum/4jre PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4jre ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NARK_ECOLI NARK_ECOLI] Involved in excretion of nitrite produced by the dissimilatory reduction of nitrate.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Mineral nitrogen in nature is often found in the form of nitrate (NO3(-)). Numerous microorganisms evolved to assimilate nitrate and use it as a major source of mineral nitrogen uptake. Nitrate, which is central in nitrogen metabolism, is first reduced to nitrite (NO2(-)) through a two-electron reduction reaction. The accumulation of cellular nitrite can be harmful because nitrite can be reduced to the cytotoxic nitric oxide. Instead, nitrite is rapidly removed from the cell by channels and transporters, or reduced to ammonium or dinitrogen through the action of assimilatory enzymes. Despite decades of effort no structure is currently available for any nitrate transport protein and the mechanism by which nitrate is transported remains largely unknown. Here we report the structure of a bacterial nitrate/nitrite transport protein, NarK, from Escherichia coli, with and without substrate. The structures reveal a positively charged substrate-translocation pathway lacking protonatable residues, suggesting that NarK functions as a nitrate/nitrite exchanger and that protons are unlikely to be co-transported. Conserved arginine residues comprise the substrate-binding pocket, which is formed by association of helices from the two halves of NarK. Key residues that are important for substrate recognition and transport are identified and related to extensive mutagenesis and functional studies. We propose that NarK exchanges nitrate for nitrite by a rocker switch mechanism facilitated by inter-domain hydrogen bond networks.

Crystal structure of a nitrate/nitrite exchanger.,Zheng H, Wisedchaisri G, Gonen T Nature. 2013 May 30;497(7451):647-51. doi: 10.1038/nature12139. Epub 2013 May 12. PMID:23665960<ref>PMID:23665960</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4jre" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Gonen T]]
[[Category: Wisedchaisri G]]
[[Category: Zheng H]]