Fig. 2: Bartoloside-fatty acid esters are formed in vivo and in vitro by BrtB.
From: BrtB is an O-alkylating enzyme that generates fatty acid-bartoloside esters
In cultures of S. salina LEGE 06099 supplemented with 50 mg L−1 of 6-heptynoic acid (2), formation of the bartoloside esters 3, 6a/6b and 4 with concomitant depletion of the corresponding bartolosides (A, 1 or G, 5) was observed by LC-HRESIMS (a). Analysis (LC-HRESIMS) of the NStrep-BrtB-mediated O-alkylation of bartoloside A (1) with 2 to generate diester 3 and monoesters 6a/6b (b) or with palmitic acid to generate monoesters 7a/7b and diester 8, the latter in much lower amount (c). Full reactions contained 1 μM recombinant NStrep-BrtB, 100 μM of 1 and 200 μM of either 2 (b) or palmitic acid (c).
