Extended Data Fig. 1: Classification of DAases by the mechanism of product release from the NRPS. | Nature Catalysis

Extended Data Fig. 1: Classification of DAases by the mechanism of product release from the NRPS.

From: Catalytic mechanism and endo-to-exo selectivity reversion of an octalin-forming natural Diels–Alderase

Extended Data Fig. 1

a, Proposed two distinct mechanisms of substrate release from the NRPS. One type of the embedded terminal reductase domain of an NRPS catalyses reduction and Knoevenagel condensation of the thioester intermediate to give a pyrrolin-2-one product via a rote A. Another type catalyses a Dieckmann condensation of the intermediate to give a pyrrolidine-2,4-dione product via a rote B. b, Phylogenetic tree of the lipocalin-type DAase homologs. Phylogenetic analysis of the amino acid sequences of the representative homologs found in the protein database revealed that they could be divided clearly into two groups based on the types of tetramic acid moieties described above that the corresponding products bear. Pink represents enzymes predicted to catalyse Knoevenagel condensation to release the pyrrolin-2-one-type (type A) product. Purple represents enzymes predicted to catalyse Dieckmann condensation to release the pyrrolidine-2,4-dione-type (type B) product. The length of the black bar is scaled to represent the evolutionary distance of 0.1 amino acid substitution per site. The enzyme names are abbreviated for the ease of representation.

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