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==Crystal structure of SsuE FMN reductase Y118A mutant in apo form.==
<StructureSection load='6dqi' size='340' side='right'caption='[[6dqi]], [[Resolution|resolution]] 1.95&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6dqi]] is a 2 chain structure with sequence from [https://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=6DQI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6DQI 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]] 1.95&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=6dqi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6dqi OCA], [https://pdbe.org/6dqi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6dqi RCSB], [https://www.ebi.ac.uk/pdbsum/6dqi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6dqi ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SSUE_ECOLI SSUE_ECOLI] Catalyzes an NADPH-dependent reduction of FMN, but is also able to reduce FAD or riboflavin.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The pi-helix located at the tetramer interface of two-component FMN-dependent reductases contributes to the structural divergence from canonical FMN-bound reductases within the NADPH:FMN reductase family. The pi-helix in the SsuE FMN-dependent reductase of the alkanesulfonate monooxygenase system has been proposed to be generated by the insertion of a Tyr residue in the conserved alpha4-helix. Variants of Tyr118 were generated, and their X-ray crystal structures determined, to evaluate how these alterations affect the structural integrity of the pi-helix. The structure of the Y118A SsuE pi-helix was converted to an alpha-helix, similar to the FMN-bound members of the NADPH:FMN reductase family. Although the pi-helix was altered, the FMN binding region remained unchanged. Conversely, deletion of Tyr118 disrupted the secondary structural properties of the pi-helix, generating a random coil region in the middle of helix 4. Both the Y118A and Delta118 SsuE SsuE variants crystallize as a dimer. The MsuE FMN reductase involved in the desulfonation of methanesulfonates is structurally similar to SsuE, but the pi-helix contains a His insertional residue. Exchanging the pi-helix insertional residue of each enzyme did not result in equivalent kinetic properties. Structure-based sequence analysis further demonstrated the presence of a similar Tyr residue in an FMN-bound reductase in the NADPH:FMN reductase family that is not sufficient to generate a pi-helix. Results from the structural and functional studies of the FMN-dependent reductases suggest that the insertional residue alone is not solely responsible for generating the pi-helix, and additional structural adaptions occur to provide the altered gain of function.

Not as easy as pi: An insertional residue does not explain the pi-helix gain-of-function in two-component FMN reductases.,McFarlane JS, Hagen RA, Chilton AS, Forbes DL, Lamb AL, Ellis HR Protein Sci. 2019 Jan;28(1):123-134. doi: 10.1002/pro.3504. Epub 2018 Nov 15. PMID:30171650<ref>PMID:30171650</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6dqi" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Ellis HR]]
[[Category: Lamb AL]]
[[Category: McFarlane JS]]