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==Crystal structure of the Coenzyme F420-dependent sulfite reductase from Methanocaldococcus jannaschii at 2.3-A resolution==
<StructureSection load='7np8' size='340' side='right'caption='[[7np8]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7np8]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Methanocaldococcus_jannaschii_DSM_2661 Methanocaldococcus jannaschii DSM 2661]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7NP8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7NP8 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]] 2.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=FAD:FLAVIN-ADENINE+DINUCLEOTIDE'>FAD</scene>, <scene name='pdbligand=FE:FE+(III)+ION'>FE</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MPD:(4S)-2-METHYL-2,4-PENTANEDIOL'>MPD</scene>, <scene name='pdbligand=SF4:IRON/SULFUR+CLUSTER'>SF4</scene>, <scene name='pdbligand=SO3:SULFITE+ION'>SO3</scene>, <scene name='pdbligand=SRM:SIROHEME'>SRM</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=7np8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7np8 OCA], [https://pdbe.org/7np8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7np8 RCSB], [https://www.ebi.ac.uk/pdbsum/7np8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7np8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/FSR_METJA FSR_METJA] Catalyzes the reduction of sulfite to sulfide using reduced F420 as the electron source. Involved in sulfite detoxification and assimilation. Cannot use NADH or NADPH.<ref>PMID:16048999</ref> <ref>PMID:18378657</ref> 
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== Publication Abstract from PubMed ==
Methanogenic archaea are main actors in the carbon cycle but are sensitive to reactive sulfite. Some methanogens use a sulfite detoxification system that combines an F(420)H(2)-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F(420)-dependent sulfite reductase (Group I Fsr), obtained from two marine methanogens. Fsr organizes as a homotetramer, harboring an intertwined six-[4Fe-4S] cluster relay characterized by spectroscopy. The wire, spanning 5.4 nm, electronically connects the flavin to the siroheme center. Despite a structural architecture similar to dissimilatory sulfite reductases, Fsr shows a siroheme coordination and a reaction mechanism identical to assimilatory sulfite reductases. Accordingly, the reaction of Fsr is unidirectional, reducing sulfite or nitrite with F(420)H(2). Our results provide structural insights into this unique fusion, in which a primitive sulfite reductase turns a poison into an elementary block of life.

Structures of the sulfite detoxifying F(420)-dependent enzyme from Methanococcales.,Jespersen M, Pierik AJ, Wagner T Nat Chem Biol. 2023 Jan 19. doi: 10.1038/s41589-022-01232-y. PMID:36658338<ref>PMID:36658338</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Methanocaldococcus jannaschii DSM 2661]]
[[Category: Jespersen M]]
[[Category: Wagner T]]