(S,S)‐2,3‐Dihydroxy‐2,3‐dihydrobenzoic Acid: Microbial Access with Engineered Cells of Escherichia coli and Application as Starting Material in Natural‐Product Synthesis

Abstract

Cyclohexadiene-trans-5,6-diols such as (S,S)-2,3-dihydroxy-2,3-dihydrobenzoic acid (2,3-trans-CHD) have been shown to be of importance as chiral starting materials for the syntheses of bioactive substances, especially for the syntheses of carbasugars. By using methods of metabolic-pathway engineering, the Escherichia coli genes entB and entC, which encode isochorismatase and isochorismate synthase, were cloned and over-expressed in E. coli strains with a deficiency of entA, which encodes 2,3-dihydroxybenzoate synthase. A 30-fold increase in the corresponding EntB/EntC enzyme activities affects the accumulation of 2,3-trans-CHD in the cultivation medium. Although the strains did not contain deletions in chorismate-utilising pathways towards aromatic amino acids, neither chorismate nor any other metabolic intermediates were found as by-products. Fermentation of these strains in a 30 L pH-controlled stirred tank reactor showed that 2,3-trans-CHD could be obtained in concentrations of up to 4.6 g L(-1). This demonstrates that post-chorismate metabolites are accessible on a preparative scale by using techniques of metabolic-pathway engineering. Isolation and separation from fermentation salts could be performed economically in one step through anion-exchange chromatography or, alternatively, by reactive extraction. Starting from 2,3-trans-CHD as an example, we established short syntheses towards new carbasugar derivatives.

Diversity‐Oriented Production of Metabolites Derived from Chorismate and Their Use in Organic Synthesis

“…We showed in earlier work that 2,3-trans-CHD (5) is a beneficial building block for the synthesis of natural product derivatives by stereo-and regioselective epoxidation and dihydroxylation. [13,14] In a similar approach, 3,4-trans-CHD (9) was regio-and stereoselectively functionalized on each of the two carbon-carbon double bonds. Steric hindrance and induced preferential conformations are the key issues for stereoselectivity.…”

Novel Insights into Siderophore Formation in Myxobacteria

“…The last compounds represent important intermediates of primary and secondary metabolism, for example, anthranilic, acid is used for aurachin biosynthesis in S. aurantiaca Sg a15 [1] and 2,3-dihydro-2,3-dihydroxybenzoic acid is an intermediate of the DHBA biosynthetic pathway. [32] l-Ornithine was used to replace l-lysine. From all of these assays, only two novel compounds (1 and 2) were identified by HPLC as shown in Figure 3.…”

Endogenous Siderophore 2,5-Dihydroxybenzoic Acid Deficiency Promotes Anemia and Splenic Iron Overload in Mice

“…EntA, an NAD ϩ -dependent 2,3-dihydro-2,3-dihydrobenzoate dehydrogenase, catalyzes the rate-limiting step in the biosynthesis of 2,3-DHBA. Elimination of EntA completely abolishes the synthesis of 2,3-DHBA (20). BDH2 is a functional homologue of bacterial EntA in eukaryotes that catalyzes an enzymatic reaction leading to the synthesis of 2,5-DHBA.…”