1372785-82-4Relevant academic research and scientific papers
Oefin isomerization regiochemistries during tandem action of BacA and BacB on prephenate in bacilysin biosynthesis
Parker, Jared B.,Walsh, Christopher T.
experimental part, p. 3241 - 3251 (2012/07/30)
BacA and BacB, the first two enzymes of the bacilysin pathway, convert prephenate to an exocylic regioisomer of dihydrohydroxyphenylpyruvate (ex-H 2HPP) on the way to the epoxycyclohexanone warhead in the dipeptide antibiotic, bacilysin. BacA decarboxylates prephenate without aromatization, converting the 1,4-diene in prephenate to the endocyclic 1,3-diene in Δ4,Δ8-dihydrohydroxyphenylpyruvate (en-H 2HPP). BacB then performs an allylic isomerization to bring the diene into conjugation with the 2-ketone in the product Δ3, Δ5-dihydrohydroxyphenylpyruvate (ex-H2HPP). To prove that BacA acts regiospecifically on one of the two prochiral olefins in prephenate, we generated 1,5,8-[13C]-chorismate from bacterial fermentation of 5-[13C]-glucose and in turn produced 2,4,6-[ 13C]-prephenate via chorismate mutase. Tandem action of BacA and BacB gave 2,4,8-[13C]-7R-ex-H2HPP, showing that BacA isomerizes only the pro-R double bond in prephenate. Nonenzymatic isomerization of the BacA product into conjugation gives only the Δ3E- geometric isomer of Δ3,Δ5-ex-H2HPP. On the other hand, acceleration of the allylic isomerization by BacB gives a mixture of the E- and Z-geometric isomers of the 7R- product, indicating some rerouting of the flux, likely through dienolate geometric isomers.
