Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada; Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, United Kingdom. Electronic address:
Published: February 2020
AI Article Synopsis
Article Abstract
Prenylated flavin mononucleotide (prFMN) is a recently discovered flavin cofactor produced by the UbiX family of FMN prenyltransferases, and is required for the activity of UbiD-like reversible decarboxylases. The latter enzymes are known to be involved in ubiquinone biosynthesis and biotransformation of lignin, aromatic compounds, and unsaturated aliphatic acids. However, exploration of uncharacterized UbiD proteins for biotechnological applications is hindered by our limited knowledge about the biochemistry of prFMN and prFMN-dependent enzymes. Here, we describe experimental protocols and considerations for the biosynthesis of prFMN in vivo and in vitro, in addition to cofactor extraction and application for activation of UbiD proteins.
Centre for Environmental Biotechnology, School of Environmental and Natural Sciences, Bangor University, Bangor, United Kingdom; Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada. Electronic address:
Microbial carboxylases and decarboxylases play important roles in the global carbon cycle and have many potential applications in biocatalysis and synthetic biology. The widespread family of reversible UbiD-like (de)carboxylases are of particular interest because these enzymes are active against a diverse range of substrates. Several characterized UbiD enzymes have been shown to catalyze reversible (de)carboxylation of aromatic and aliphatic substrates using the recently discovered prenylated FMN (prFMN) cofactor, which is produced by the associated family of UbiX FMN prenyltransferases.
The microbial UbiX-UbiD system facilitates the reversible (de)carboxylation of alpha, beta-unsaturated carboxylic acids, including aromatic compounds. The direct C-H carboxylation presents an attractive method for functionalisation and carbon capture but is difficult to achieve under mild conditions. Hence, UbiD-mediated Csp2-H activation can serve as a versatile tool for developing new biocatalytic routes to transform aryl or alkene compounds and carbon dioxide into valuable commodity chemicals.
Prenylated-FMN (prFMN) is the cofactor used by the UbiD-like family of decarboxylases that catalyzes the decarboxylation of various aromatic and unsaturated carboxylic acids. prFMN is synthesized from reduced FMN and dimethylallyl phosphate (DMAP) by a specialized prenyl transferase, UbiX. UbiX catalyzes the sequential formation of two bonds, the first between N5 of the flavin and C1 of DMAP, and the second between C6 of the flavin and C3 of DMAP.
The prenylated-flavin mononucleotide-dependent decarboxylases (also known as UbiD-like enzymes) are the most recently discovered family of decarboxylases. The modified flavin facilitates the decarboxylation of unsaturated carboxylic acids through a novel mechanism involving 1,3-dipolar cyclo-addition chemistry. UbiD-like enzymes have attracted considerable interest for biocatalysis applications due to their ability to catalyse (de)carboxylation reactions on a broad range of aromatic substrates at otherwise unreactive carbon centres.
The UbiD enzyme family of prenylated flavin (prFMN)-dependent reversible decarboxylases is near ubiquitously present in microbes. For some UbiD family members, enzyme activation through prFMNH binding and subsequent oxidative maturation of the cofactor readily occurs, both in vivo in a heterologous host and through in vitro reconstitution. However, isolation of the active holo-enzyme has proven intractable for others, notably the canonical Escherichia coli UbiD.
