Fig. 1: Selected O- and C-alkylating enzymes.
From: BrtB is an O-alkylating enzyme that generates fatty acid-bartoloside esters
a BioC is a SAM-dependent methyltransferase acting in biotin biosynthesis. b CMLE is an eukaryotic beta-propeller enzyme catalyzing an intramolecular addition of a carboxylate to a double bond. c NosN, a radical SAM enzyme, generates an exomethylene intermediate that drives intramolecular ester bond formation. d Dehalogenation of alkyl halides catalyzed by l-2-haloacid dehalogenases involves the transient formation of an ester species resulting from the nucleophilic attack of a side chain carboxylate onto the chlorinated carbon. e In cylindrocyclophane biosynthesis, each alkylresorcinol moiety is alkylated at the C-2 position by CylK. f The brt gene cluster from Synechocystis salina LEGE 06099 encodes the production of a number of bartolosides, the most abundant of which are bartolosides 1 and 5 (depicted). g BrtB catalyzes O–C bond formation between non-activated fatty acids and bartolosides.
