Structural highlights
Function
[ISLA_BILW3] Involved in an anaerobic respiration pathway that converts the sulfonate taurine (2-aminoethanesulfonate) to ammonia, acetate and sulfide. Catalyzes the radical-mediated C-S bond cleavage of isethionate (2-hydroxyethanesulfonate) to form sulfite and acetaldehyde. Is not able to use any alternate organosulfonate or (S)-1,2-propanediol or choline as a substrate, showing that this enzyme is highly specific for isethionate.[1]
Publication Abstract from PubMed
Desulfonation of isethionate by the bacterial glycyl radical enzyme (GRE) isethionate sulfite-lyase (IslA) generates sulfite, a substrate for respiration that in turn produces the disease-associated metabolite hydrogen sulfide. Here, we present a 2.7 A resolution X-ray structure of wild-type IslA from Bilophila wadsworthia with isethionate bound. In comparison with other GREs, alternate positioning of the active site beta strands allows for distinct residue positions to contribute to substrate binding. These structural differences, combined with sequence variations, create a highly tailored active site for the binding of the negatively charged isethionate substrate. Through the kinetic analysis of 14 IslA variants and computational analyses, we probe the mechanism by which radical chemistry is used for C-S bond cleavage. This work further elucidates the structural basis of chemistry within the GRE superfamily and will inform structure-based inhibitor design of IsIA and thus of microbial hydrogen sulfide production.
Molecular basis of C-S bond cleavage in the glycyl radical enzyme isethionate sulfite-lyase.,Dawson CD, Irwin SM, Backman LRF, Le C, Wang JX, Vennelakanti V, Yang Z, Kulik HJ, Drennan CL, Balskus EP Cell Chem Biol. 2021 Mar 19. pii: S2451-9456(21)00110-0. doi:, 10.1016/j.chembiol.2021.03.001. PMID:33773110[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Peck SC, Denger K, Burrichter A, Irwin SM, Balskus EP, Schleheck D. A glycyl radical enzyme enables hydrogen sulfide production by the human intestinal bacterium Bilophila wadsworthia. Proc Natl Acad Sci U S A. 2019 Feb 19;116(8):3171-3176. doi:, 10.1073/pnas.1815661116. Epub 2019 Feb 4. PMID:30718429 doi:http://dx.doi.org/10.1073/pnas.1815661116
- ↑ Dawson CD, Irwin SM, Backman LRF, Le C, Wang JX, Vennelakanti V, Yang Z, Kulik HJ, Drennan CL, Balskus EP. Molecular basis of C-S bond cleavage in the glycyl radical enzyme isethionate sulfite-lyase. Cell Chem Biol. 2021 Mar 19. pii: S2451-9456(21)00110-0. doi:, 10.1016/j.chembiol.2021.03.001. PMID:33773110 doi:http://dx.doi.org/10.1016/j.chembiol.2021.03.001
