View source for 6veb


==Precorrin-2-bound S128A S. typhimurium siroheme synthase==
<StructureSection load='6veb' size='340' side='right'caption='[[6veb]], [[Resolution|resolution]] 2.55&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6veb]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Salmonella_enterica_subsp._enterica Salmonella enterica subsp. enterica]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6VEB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6VEB 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]] 2.55&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=NAD:NICOTINAMIDE-ADENINE-DINUCLEOTIDE'>NAD</scene>, <scene name='pdbligand=PQ2:3,3,3,3-[(7S,8S,12S,13S)-3,8,13,17-tetrakis(carboxymethyl)-8,13-dimethyl-7,8,12,13,20,24-hexahydroporphyrin-2,7,12,18-tetrayl]tetrapropanoic+acid'>PQ2</scene>, <scene name='pdbligand=SAH:S-ADENOSYL-L-HOMOCYSTEINE'>SAH</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=6veb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6veb OCA], [https://pdbe.org/6veb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6veb RCSB], [https://www.ebi.ac.uk/pdbsum/6veb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6veb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CYSG_SALTY CYSG_SALTY] Multifunctional enzyme that catalyzes the SAM-dependent methylations of uroporphyrinogen III at position C-2 and C-7 to form precorrin-2 via precorrin-1. Then it catalyzes the NAD-dependent ring dehydrogenation of precorrin-2 to yield sirohydrochlorin. Finally, it catalyzes the ferrochelation of sirohydrochlorin to yield siroheme.<ref>PMID:14595395</ref> 
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== Publication Abstract from PubMed ==
Siroheme is the central cofactor in a conserved class of sulfite and nitrite reductases that catalyze the six-electron reduction of sulfite to sulfide and nitrite to ammonia. In Salmonella enterica serovar Typhimurium, siroheme is produced by a trifunctional enzyme, siroheme synthase (CysG). A bifunctional active site that is distinct from its methyltransferase activity catalyzes the final two steps, NAD(+)-dependent dehydrogenation and iron chelation. How this active site performs such different chemistries is unknown. Here, we report the structures of CysG bound to precorrin-2, the initial substrate; sirohydrochlorin, the dehydrogenation product/chelation substrate; and a cobalt-sirohydrochlorin product. We identified binding poses for all three tetrapyrroles and tested the roles of specific amino acids in both activities to give insights into how a bifunctional active site catalyzes two different chemistries and acts as an iron-specific chelatase in the final step of siroheme synthesis.

Siroheme synthase orients substrates for dehydrogenase and chelatase activities in a common active site.,Pennington JM, Kemp M, McGarry L, Chen Y, Stroupe ME Nat Commun. 2020 Feb 13;11(1):864. doi: 10.1038/s41467-020-14722-1. PMID:32054833<ref>PMID:32054833</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6veb" style="background-color:#fffaf0;"></div>

==See Also==
*[[Siroheme synthase|Siroheme synthase]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Salmonella enterica subsp. enterica]]
[[Category: Pennington JM]]
[[Category: Stroupe ME]]