Rieske Oxygenase Catalyzed C-H Bond Functionalization Reactions in Chlorophyll Biosynthesis.

Rieske oxygenases perform precise C-H bond functionalization reactions in anabolic and catabolic pathways. These reactions are typically characterized as monooxygenation or dioxygenation reactions, but other divergent reactions are also catalyzed by Rieske oxygenases. Chlorophyll(ide) oxygenase (CAO), for example is proposed to catalyze two monooxygenation reactions to transform a methyl-group into the formyl-group of Chlorophyll .

Purification and structural elucidation of a cobalamin-dependent radical SAM enzyme.

The cobalamin (Cbl)-dependent radical S-adenosylmethionine (SAM) enzymes use a [4Fe-4S] cluster, SAM, and Cbl to carry out remarkable catalytic feats in a large number of biosynthetic pathways. However, despite the abundance of annotated Cbl-dependent radical SAM enzymes, relatively few molecular details exist regarding how these enzymes function. Traditionally, challenges associated with purifying and reconstituting Cbl-dependent radical SAM enzymes have hindered biochemical studies aimed at elucidating the structures and mechanisms of these enzymes.

The A-type domain in NfuA is required for regenerating the auxiliary [4Fe-4S] cluster in lipoyl synthase.

The lipoyl cofactor plays an integral role in several essential biological processes. The last step in its biosynthetic pathway, the attachment of two sulfur atoms at C6 and C8 of an -octanoyllysyl chain, is catalyzed by lipoyl synthase (LipA), a member of the radical SAM superfamily. In addition to the [4Fe-4S] cluster common to all radical SAM enzymes, LipA contains a second [4Fe-4S] auxiliary cluster, which is sacrificed during catalysis to supply the requisite sulfur atoms, rendering the protein inactive for further turnovers.