2xxf: Difference between revisions
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< | ==Cu metallated H254F mutant of nitrite reductase== | ||
<StructureSection load='2xxf' size='340' side='right'caption='[[2xxf]], [[Resolution|resolution]] 1.50Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[2xxf]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Achromobacter_xylosoxidans Achromobacter xylosoxidans]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=2jl3 2jl3]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2XXF OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2XXF 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]] 1.5Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CU:COPPER+(II)+ION'>CU</scene>, <scene name='pdbligand=MES:2-(N-MORPHOLINO)-ETHANESULFONIC+ACID'>MES</scene>, <scene name='pdbligand=PEG:DI(HYDROXYETHYL)ETHER'>PEG</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</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=2xxf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2xxf OCA], [https://pdbe.org/2xxf PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2xxf RCSB], [https://www.ebi.ac.uk/pdbsum/2xxf PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2xxf ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/O68601_ALCXX O68601_ALCXX] | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
We demonstrated recently that two protons are involved in reduction of nitrite to nitric oxide through a proton-coupled electron transfer (ET) reaction catalyzed by the blue Cu-dependent nitrite reductase (Cu NiR) of Alcaligenes xylosoxidans (AxNiR). Here, the functionality of two putative proton channels, one involving Asn90 and the other His254, is studied using single (N90S, H254F) and double (N90S-H254F) mutants. All mutants studied are active, indicating that protons are still able to reach the active site. The H254F mutation has no effect on the catalytic activity, while the N90S mutation results in approximately 70% decrease in activity. Laser flash-photolysis experiments show that in H254F and wild-type enzyme electrons enter at the level of the T1Cu and then redistribute between the two Cu sites. Complete ET from T1Cu to T2Cu occurs only when nitrite binds at the T2Cu site. This indicates that substrate binding to T2Cu promotes ET from T1Cu, suggesting that the enzyme operates an ordered mechanism. In fact, in the N90S and N90S-H254F variants, where the T1Cu site redox potential is elevated by approximately 60 mV, inter-Cu ET is only observed in the presence of nitrite. From these results it is evident that the Asn90 channel is the main proton channel in AxNiR, though protons can still reach the active site if this channel is disrupted. Crystallographic structures provide a clear structural rationale for these observations, including restoration of the proton delivery via a significant movement of the loop connecting the T1Cu ligands Cys130 and His139 that occurs on binding of nitrite. Notably, a role for this loop in facilitating interaction of cytochrome c(551) with Cu NiR has been suggested previously based on a crystal structure of the binary complex. | |||
Proton-Coupled Electron Transfer in the Catalytic Cycle of Alcaligenes xylosoxidans Copper-Dependent Nitrite Reductase.,Leferink NG, Han C, Antonyuk SV, Heyes DJ, Rigby SE, Hough MA, Eady RR, Scrutton NS, Hasnain SS Biochemistry. 2011 May 17;50(19):4121-31. Epub 2011 Apr 19. PMID:21469743<ref>PMID:21469743</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 2xxf" style="background-color:#fffaf0;"></div> | |||
==See Also== | |||
*[[Nitrite reductase 3D structures|Nitrite reductase 3D structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
[[ | |||
== | |||
< | |||
[[Category: Achromobacter xylosoxidans]] | [[Category: Achromobacter xylosoxidans]] | ||
[[Category: Eady | [[Category: Large Structures]] | ||
[[Category: Hasnain | [[Category: Eady RR]] | ||
[[Category: Hough | [[Category: Hasnain SS]] | ||
[[Category: Hough MA]] | |||
Latest revision as of 13:40, 20 December 2023
Cu metallated H254F mutant of nitrite reductaseCu metallated H254F mutant of nitrite reductase
Structural highlights
FunctionPublication Abstract from PubMedWe demonstrated recently that two protons are involved in reduction of nitrite to nitric oxide through a proton-coupled electron transfer (ET) reaction catalyzed by the blue Cu-dependent nitrite reductase (Cu NiR) of Alcaligenes xylosoxidans (AxNiR). Here, the functionality of two putative proton channels, one involving Asn90 and the other His254, is studied using single (N90S, H254F) and double (N90S-H254F) mutants. All mutants studied are active, indicating that protons are still able to reach the active site. The H254F mutation has no effect on the catalytic activity, while the N90S mutation results in approximately 70% decrease in activity. Laser flash-photolysis experiments show that in H254F and wild-type enzyme electrons enter at the level of the T1Cu and then redistribute between the two Cu sites. Complete ET from T1Cu to T2Cu occurs only when nitrite binds at the T2Cu site. This indicates that substrate binding to T2Cu promotes ET from T1Cu, suggesting that the enzyme operates an ordered mechanism. In fact, in the N90S and N90S-H254F variants, where the T1Cu site redox potential is elevated by approximately 60 mV, inter-Cu ET is only observed in the presence of nitrite. From these results it is evident that the Asn90 channel is the main proton channel in AxNiR, though protons can still reach the active site if this channel is disrupted. Crystallographic structures provide a clear structural rationale for these observations, including restoration of the proton delivery via a significant movement of the loop connecting the T1Cu ligands Cys130 and His139 that occurs on binding of nitrite. Notably, a role for this loop in facilitating interaction of cytochrome c(551) with Cu NiR has been suggested previously based on a crystal structure of the binary complex. Proton-Coupled Electron Transfer in the Catalytic Cycle of Alcaligenes xylosoxidans Copper-Dependent Nitrite Reductase.,Leferink NG, Han C, Antonyuk SV, Heyes DJ, Rigby SE, Hough MA, Eady RR, Scrutton NS, Hasnain SS Biochemistry. 2011 May 17;50(19):4121-31. Epub 2011 Apr 19. PMID:21469743[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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