6PR0
P133H-S128A S. typhimurium siroheme synthase
Summary for 6PR0
| Entry DOI | 10.2210/pdb6pr0/pdb |
| Related | 1PJS |
| Descriptor | Siroheme synthase, S-ADENOSYL-L-HOMOCYSTEINE (3 entities in total) |
| Functional Keywords | precorrin-2, tetrapyrrole biosynthesis, cysg, transferase |
| Biological source | Salmonella typhimurium |
| Total number of polymer chains | 2 |
| Total formula weight | 101231.88 |
| Authors | Pennington, J.M.,Stroupe, M.E. (deposition date: 2019-07-10, release date: 2020-02-26, Last modification date: 2023-10-11) |
| Primary citation | Pennington, J.M.,Kemp, M.,McGarry, L.,Chen, Y.,Stroupe, M.E. Siroheme synthase orients substrates for dehydrogenase and chelatase activities in a common active site. Nat Commun, 11:864-864, 2020 Cited by PubMed Abstract: 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. PubMed: 32054833DOI: 10.1038/s41467-020-14722-1 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.9 Å) |
Structure validation
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