A discrete intermediate for the biosynthesis of both the enediyne core and the anthraquinone moiety of enediyne natural products.

The enediynes are structurally characterized by a 1,5-diyne-3-ene motif within a 9- or 10-membered enediyne core. The anthraquinone-fused enediynes (AFEs) are a subclass of 10-membered enediynes that contain an anthraquinone moiety fused to the enediyne core as exemplified by dynemicins and tiancimycins. A conserved iterative type I polyketide synthase (PKSE) is known to initiate the biosynthesis of all enediyne cores, and evidence has recently been reported to suggest that the anthraquinone moiety also originates from the PKSE product.

Genetic Incorporation of Noncanonical Amino Acids Using Two Mutually Orthogonal Quadruplet Codons.

Genetic incorporation of noncanonical amino acids has emerged as a powerful tool for the study of protein structure and function. While the three triplet nonsense codons have been widely explored, quadruplet codons have attracted attention for the potential of creating additional blank codons for noncanonical amino acid mutagenesis. Here we demonstrated for the first time that two orthogonal quadruplet codons could be used to simultaneously encode two different noncanonical amino acids within a single protein in bacterial cells.

Characterization of Carboxylic Acid Reductases for Biocatalytic Synthesis of Industrial Chemicals.

Carboxylic acid reductases (CARs) catalyze the reduction of a broad range of carboxylic acids into aldehydes, which can serve as common biosynthetic precursors to many industrial chemicals. This work presents the systematic biochemical characterization of five carboxylic acid reductases from different microorganisms, including two known and three new ones, by using a panel of short-chain dicarboxylic acids and hydroxy acids, which are common cellular metabolites. All enzymes displayed broad substrate specificities.