Evidence of substrate binding and product release via belt-sulfur mobilization of the nitrogenase cofactoropen access
- Authors
- Lee, Chi Chung; Kang, Wonchull; Jasniewski, Andrew J.; Stiebritz, Martin T.; Tanifuji, Kazuki; Ribbe, Markus W.; Hu, Yilin
- Issue Date
- May-2022
- Publisher
- NATURE PORTFOLIO
- Citation
- NATURE CATALYSIS, v.5, no.5, pp.443 - 454
- Journal Title
- NATURE CATALYSIS
- Volume
- 5
- Number
- 5
- Start Page
- 443
- End Page
- 454
- URI
- http://scholarworks.bwise.kr/ssu/handle/2018.sw.ssu/42942
- DOI
- 10.1038/s41929-022-00782-7
- ISSN
- 2520-1158
- Abstract
- Molybdenum nitrogenase catalyses the ambient reduction of N-2 to NH3 at the M-cluster, a complex cofactor that comprises two metal-sulfur partial cubanes ligated by an interstitial carbide and three belt-sulfurs. A recent crystallographic study suggests binding of N-2 via displacement of the belt-sulfur(s) of the M-cluster upon turnover. However, direct proof of N-2 binding and belt-sulfur mobilization during catalysis remains elusive. Here we show that N-2 is captured on the M-cluster via electron and sulfur depletion, and that the N-2-captured state is catalytically competent in generating NH3. Moreover, we demonstrate that product release occurs only when sulfite is supplied along with a reductant, that sulfite is inserted as sulfide into the belt-sulfur-displaced positions and that there is a dynamic in-and-out of belt-sulfurs during catalysis. Together, these results establish the mobilization of cofactor belt-sulfurs as a crucial, yet overlooked, mechanistic element of the nitrogenase reaction.
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