Diketopiperazines as advanced intermediates in the biosynthesis of ecteinascidins

abstract: The ecteinascidins are a family of tetrahydroisoquinoline alkaloids isolated from the tunicate Ecteinascidia turbinata. Ecteinascidin 743 is a candidate for the treatment of several human cancers. Ecteinascidins have been shown to kill tumor cells in vitro, inhibit tumor growth in vivo, suppress allograft rejection, diminish host reactions to tissue grafts, and inhibit lymphocyte proliferation. The ecteinascidins have two mechanisms of action -- they are unique alkylating agents and also disaggregate microtubule complexes without affecting tubulin itself. In this paper, the diketopiperazines of phenylalanine, tyrosine and DOPA were synthesized from 14 C-labeled amino acids and clarified as intermediates in the biosynthesis of the ecteinascidins

Analysis of 51 cyclodipeptide synthases reveals the basis for substrate specificity.

International audienceCyclodipeptide synthases (CDPSs) constitute a family of peptide bond-forming enzymes that use aminoacyl-tRNAs for the synthesis of cyclodipeptides. Here, we describe the activity of 41 new CDPSs. We also show that CDPSs can be classified into two main phylogenetically distinct subfamilies characterized by specific functional subsequence signatures, named NYH and XYP. All 11 previously characterized CDPSs belong to the NYH subfamily, suggesting that further special features may be yet to be discovered in the other subfamily. CDPSs synthesize a large diversity of cyclodipeptides made up of 17 proteinogenic amino acids. The identification of several CDPSs having the same specificity led us to determine specificity sequence motifs that, in combination with the phylogenetic distribution of CDPSs, provide a first step toward being able to predict the cyclodipeptides synthesized by newly discovered CDPSs. The determination of the activity of ten more CDPSs with predicted functions constitutes a first experimental validation of this predictive approach

Cyclodipeptide synthases are a family of tRNA-dependent peptide bond–forming enzymes

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