Structural Bases of Dihydroxy Acid Dehydratase Inhibition and Biodesign for Self-Resistance.

Dihydroxy acid dehydratase (DHAD) is the third enzyme in the plant branched-chain amino acid biosynthetic pathway and the target for commercial herbicide development. We have previously reported the discovery of fungal natural product aspterric acid (AA) as a submicromolar inhibitor of DHAD through self-resistance gene directed genome mining. Here, we reveal the mechanism of AA inhibition on DHAD and the self-resistance mechanism of AstD, which is encoded by the self-resistance gene D.

Cell-Free Total Biosynthesis of Plant Terpene Natural Products using an Orthogonal Cofactor Regeneration System.

Here we report the one-pot, cell-free enzymatic synthesis of the plant monoterpene nepetalactol starting from the readily available geraniol. A pair of orthogonal cofactor regeneration systems permitted NAD-dependent geraniol oxidation followed by NADPH-dependent reductive cyclization without isolation of intermediates. The orthogonal cofactor regeneration system maintained a high ratio of NAD to NADH and a low ratio of NADP to NADPH.

Iterative Catalysis in the Biosynthesis of Mitochondrial Complex II Inhibitors Harzianopyridone and Atpenin B.

The pentasubstituted pyridine natural products harzianopyridone and atpenins are potent inhibitors of mitochondrial complex II. We identified the pathways of these compounds from their fungal producers and uncovered that the biosynthetic steps require multiple iterative enzymes. In particular, a methyltransferase and a flavin-dependent monooxygenase are used iteratively to introduce C5 and C6 methoxy groups.

Isolation of four xylanases capable of hydrolyzing corn fiber xylan from sp. H2C.

Corn fibre xylan (CX) shows high resistance to enzymatic hydrolysis due to its densely decorated side chains. To find enzymes capable of hydrolyzing CX, we isolated a bacterial strain (named H2C) from soil, by enrichment culture using non-starch polysaccharides of corn as the sole carbon source. Analysis based on the 16S rRNA sequence placed strain H2C within genus .

Resistance-gene-directed discovery of a natural-product herbicide with a new mode of action.

Bioactive natural products have evolved to inhibit specific cellular targets and have served as lead molecules for health and agricultural applications for the past century. The post-genomics era has brought a renaissance in the discovery of natural products using synthetic-biology tools. However, compared to traditional bioactivity-guided approaches, genome mining of natural products with specific and potent biological activities remains challenging.