Molecular Basis of C–N Bond Cleavage by the Glycyl Radical Enzyme Choline Trimethylamine-Lyase. Issue 10 (20th October 2016)

• Record Type: Journal Article
• Authors: Bodea, Smaranda; Funk, Michael A.; Balskus, Emily P.; Drennan, Catherine L.
• Is Part Of: Cell chemical biology. Volume 23:Issue 10(2016)
• Page Start: 1206
• Page End: 1216
• Publication Date: 2016-10-20
• Subjects: Biochemistry -- Periodicals; 572.05
• DOI: 10.1016/j.chembiol.2016.07.020
• Languages: English
• ISSNs: 2451-9456

Abstract

Summary: Deamination of choline catalyzed by the glycyl radical enzyme choline trimethylamine-lyase (CutC) has emerged as an important route for the production of trimethylamine, a microbial metabolite associated with both human disease and biological methane production. Here, we have determined five high-resolution X-ray structures of wild-type CutC and mechanistically informative mutants in the presence of choline. Within an unexpectedly polar active site, CutC orients choline through hydrogen bonding with a putative general base, and through close interactions between phenolic and carboxylate oxygen atoms of the protein scaffold and the polarized methyl groups of the trimethylammonium moiety. These structural data, along with biochemical analysis of active site mutants, support a mechanism that involves direct elimination of trimethylamine. This work broadens our understanding of radical-based enzyme catalysis and will aid in the rational design of inhibitors of bacterial trimethylamine production. Graphical Abstract: Highlights: Molecular basis for trimethylamine production in human gut Crystallographic snapshots of radical-based enzyme catalysis CH—O hydrogen bonds help bind choline in an enzyme active site Microbial mechanism and human health linkage explored Abstract : This crystallographic and biochemical study provides a molecular depiction of how trimethylamine, a metabolite associated with both liver and cardiovascular disease, is generated from choline by the human gut microbiota.