View source for 6fpi


==Structure of fully reduced Hydrogenase (Hyd-1) variant E28Q==
<StructureSection load='6fpi' size='340' side='right' caption='[[6fpi]], [[Resolution|resolution]] 1.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6fpi]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Escherichia_coli_k-12 Escherichia coli k-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6FPI OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6FPI FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=EJ2:NI-FE+REDUCED+ACTIVE+CENTER'>EJ2</scene>, <scene name='pdbligand=F3S:FE3-S4+CLUSTER'>F3S</scene>, <scene name='pdbligand=LMT:DODECYL-BETA-D-MALTOSIDE'>LMT</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=SF3:FE4-S3+CLUSTER'>SF3</scene>, <scene name='pdbligand=SF4:IRON/SULFUR+CLUSTER'>SF4</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[5lmm|5lmm]]</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Hydrogenase_(acceptor) Hydrogenase (acceptor)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.12.99.6 1.12.99.6] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6fpi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6fpi OCA], [http://pdbe.org/6fpi PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6fpi RCSB], [http://www.ebi.ac.uk/pdbsum/6fpi PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6fpi ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/MBHS_ECOLI MBHS_ECOLI]] This is one of three E.coli hydrogenases synthesized in response to different physiological conditions. HYD1 is believed to have a role in hydrogen cycling during fermentative growth. [[http://www.uniprot.org/uniprot/MBHL_ECOLI MBHL_ECOLI]] This is one of three E.coli hydrogenases synthesized in response to different physiological conditions. HYD1 is believed to have a role in hydrogen cycling during fermentative growth. 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Catalytic long-range proton transfer in [NiFe]-hydrogenases has long been associated with a highly conserved glutamate (E) situated within 4 A of the active site. Substituting for glutamine (Q) in the O2-tolerant [NiFe]-hydrogenase-1 from Escherichia coli produces a variant (E28Q) with unique properties that have been investigated using protein film electrochemistry, protein film infrared electrochemistry, and X-ray crystallography. At pH 7 and moderate potential, E28Q displays approximately 1% of the activity of the native enzyme, high enough to allow detailed infrared measurements under steady-state conditions. Atomic-level crystal structures reveal partial displacement of the amide side chain by a hydroxide ion, the occupancy of which increases with pH or under oxidizing conditions supporting formation of the superoxidized state of the unusual proximal [4Fe-3S] cluster located nearby. Under these special conditions, the essential exit pathway for at least one of the H(+) ions produced by H2 oxidation, and assumed to be blocked in the E28Q variant, is partially repaired. During steady-state H2 oxidation at neutral pH (i.e., when the barrier to H(+) exit via Q28 is almost totally closed), the catalytic cycle is dominated by the reduced states "Nia-R" and "Nia-C", even under highly oxidizing conditions. Hence, E28 is not involved in the initial activation/deprotonation of H2, but facilitates H(+) exit later in the catalytic cycle to regenerate the initial oxidized active state, assumed to be Nia-SI. Accordingly, the oxidized inactive resting state, "Ni-B", is not produced by E28Q in the presence of H2 at high potential because Nia-SI (the precursor for Ni-B) cannot accumulate. The results have important implications for understanding the catalytic mechanism of [NiFe]-hydrogenases and the control of long-range proton-coupled electron transfer in hydrogenases and other enzymes.

Mechanistic Exploitation of a Self-Repairing, Blocked Proton Transfer Pathway in an O2-Tolerant [NiFe]-Hydrogenase.,Evans RM, Ash PA, Beaton SE, Brooke EJ, Vincent KA, Carr SB, Armstrong FA J Am Chem Soc. 2018 Aug 15;140(32):10208-10220. doi: 10.1021/jacs.8b04798. Epub, 2018 Aug 2. PMID:30070475<ref>PMID:30070475</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6fpi" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli k-12]]
[[Category: Armstrong, F A]]
[[Category: Carr, S B]]
[[Category: Evans, R M]]
[[Category: Hydrogen]]
[[Category: Iron sulphur cluster]]
[[Category: Nife hydrogenase]]
[[Category: Oxidoreductase]]
[[Category: Periplasm]]