Unprecedented Noncanonical Features of the Nonlinear Nonribosomal Peptide Synthetase Assembly Line for WS9326A Biosynthesis

Abstract

Systematic inactivation of nonribosomal peptide synthetase (NRPS) domains and translocation of the thioesterase (TE) domain revealed several unprecedented nonlinear NRPS assembly processes during the biosynthesis of the cyclodepsipeptide WS9326A in Streptomyces sp. SNM55. First, two sets of type ΙΙ TE (TEΙΙ)‐like enzymes mediate the shuttling of activated amino acids between two sets of stand‐alone adenylation (A)‐thiolation (T) didomain modules and an “A‐less” condensation (C)‐T module with distinctive specificities and flexibilities. This was confirmed by the elucidation of the affinities of the A‐T didomains for the TEΙΙs and its structure. Second, the C‐T didomain module operates iteratively and independently from other modules in the same protein to catalyze two chain elongation cycles. Third, this biosynthetic pathway includes the first example of module skipping, where the interpolated C and T domains are required for chain transfer.

Taeanamides A and B, Nonribosomal Lipo-Decapeptides Isolated from an Intertidal-Mudflat-Derived Streptomyces sp.

“…SNM55 and were reported to act as Candida albicans isocitrate lyase inhibitors [8]. Deeper analysis of the metabolites and the genomic sequence of the SNM55 strain elucidated unprecedented noncanonical features in terms of the biosynthesis of WS9326A [9]. Furthermore, our co-cultivation of marine Streptomyces and Bacillus strains induced the production of a new cyclic hexapeptide, dentigerumycin E, and we elucidated its NRP biosynthetic pathway along with its antiproliferative and antimetastatic activities against human cancer cell lines [10].…”

Identification of the Cirratiomycin Biosynthesis Gene Cluster in Streptomyces Cirratus: Elucidation of the Biosynthetic Pathways for 2,3‐Diaminobutyric Acid and Hydroxymethylserine

“…[47] CirA9 belongs to the same clade as LgnA, Cal20, and Cal5, the thioesterases which were shown to catalyze transacylation of an amino acid between two T domains. [5,6] Therefore, CirA9 was assumed to have a similar function and was expected to transfer an amino acid from an AÀ T didomain (CirA2 or CirA4) to an NRPS module lacking the A domain (the first module of CirA10 or CirA8). In contrast, CirA12 belongs to a different clade (Figure S11).…”

“…[4] Since the first module lacks the A domain, which selects and activates the amino acid, the module was reported to use an alternative strategy to load an amino acid; a specific type II thioesterase (Te II ) catalyzes the transfer of an aminoacyl chain to the T 1 domain of the assembly line from another T domain. [5,6] Another example of an unusual assembly line is that with an X domain. The X domain is a homolog of the C domain that lacks catalytic activity and recruits monooxygenase to oxidize a peptide intermediate tethered to the T domain.…”

Engineering of Specific Single-Module Nonribosomal Peptide Synthetases of the RXP Type for the Production of Defined Peptides

“…Nonlinear type C NRPSs are literally the extended family of iterative NRPSs. The domain organizations are generally unusual and certain domain is inactive but another acts more than once for the assembly of one or multiple NRPs. , They can be represented by VibF for the synthesis of siderophore vibriobactin, more impressive NRPSs involved in yersiniabactin − and WS9326A biosynthesis, respectively. However, with an increasing number of reports on ribosomally independent peptides that are assembled by atypical NRPS systems, the Hertweck group recognized the problem of previous NRPS nomenclature and recently proposed a new framework to classify ribosome-independent peptide synthetases.…”