5glg
From Proteopedia
The novel function of Osm1 under anaerobic condition in the ER was revealed by crystal structure of Osm1, a soluble fumarate reductase in yeast
Structural highlights
FunctionOSM1_YEAST Irreversibly catalyzes the reduction of fumarate to succinate. Together with the second isozyme of soluble fumarate reductase (FRD1), essential for anaerobic growth. Involved in maintaining redox balance during oxygen deficiency conditions. Reduction of fumarate is the main source of succinate during fermentation, and under anaerobic conditions, the formation of succinate is strictly required for the reoxidation of FADH(2).[1] [2] [3] [4] Publication Abstract from PubMedOsm1 and Frd1 are soluble fumarate reductases from yeast that are critical for allowing survival under anaerobic conditions. Although they maintain redox balance during anaerobiosis, the underlying mechanism is not understood. Here, we report the crystal structure of a eukaryotic soluble fumarate reductase, which is unique among soluble fumarate reductases as it lacks a heme domain. Structural and enzymatic analyses indicate that Osm1 has a specific binding pocket for flavin molecules, including FAD, FMN, and riboflavin, catalyzing their oxidation while reducing fumarate to succinate. Moreover, ER-resident Osm1 can transfer electrons from the Ero1 FAD cofactor to fumarate either by free FAD or by a direct interaction, allowing de novo disulfide bond formation in the absence of oxygen. We conclude that soluble eukaryotic fumarate reductases can maintain an oxidizing environment under anaerobic conditions, either by oxidizing cellular flavin cofactors or by a direct interaction with flavoenzymes such as Ero1. Molecular basis of maintaining an oxidizing environment under anaerobiosis by soluble fumarate reductase.,Kim S, Kim CM, Son YJ, Choi JY, Siegenthaler RK, Lee Y, Jang TH, Song J, Kang H, Kaiser CA, Park HH Nat Commun. 2018 Nov 19;9(1):4867. doi: 10.1038/s41467-018-07285-9. PMID:30451826[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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