Heterologous characterization of mechercharmycin A biosynthesis reveals alternative insights into post-translational modifications for RiPPs.

Mechercharmycin A (MCM-A) is a marine natural product belonging to a family of polyazole cyclopeptides with remarkable bioactivities and unique structures. Identification, heterologous expression, and genetic characterizations of the MCM biosynthetic gene cluster in Bacillus subtilis revealed that it is a ribosomally synthesized and post-translationally modified peptide (RiPP) possessing complex with distinctive modifications. Based on this heterologous expression system, two MCM analogs with comparable antitumor activity are generated by engineering the biosynthetic pathway.

Directed production of aurantizolicin and new members based on a YM-216391 biosynthetic system.

Using a highly effective heterologous expression system, the YM-216391 (1) biosynthetic gene cluster was engineered to yield aurantizolicin (2) and the hybrid compound 3. Both of these compounds were isolated and fully structurally characterised and the bioactivity was evaluated. The results indicate that compound 3 exhibits significantly improved antitumor activity.

A radical S-adenosyl-L-methionine enzyme and a methyltransferase catalyze cyclopropane formation in natural product biosynthesis.

Cyclopropanation of unactivated olefinic bonds via addition of a reactive one-carbon species is well developed in synthetic chemistry, whereas natural cyclopropane biosynthesis employing this strategy is very limited. Here, we identify a two-component cyclopropanase system, composed of a HemN-like radical S-adenosyl-L-methionine (SAM) enzyme C10P and a methyltransferase C10Q, catalyzes chemically challenging cyclopropanation in the antitumor antibiotic CC-1065 biosynthesis. C10P uses its [4Fe-4S] cluster for reductive cleavage of the first SAM to yield a highly reactive 5'-deoxyadenosyl radical, which abstracts a hydrogen from the second SAM to produce a SAM methylene radical that adds to an sp-hybridized carbon of substrate to form a SAM-substrate adduct.

A Six-Oxidase Cascade for Tandem C-H Bond Activation Revealed by Reconstitution of Bicyclomycin Biosynthesis.

As a commercial antibiotic, bicyclomycin (BCM) is currently the only known natural product targeting the transcription termination factor rho. It belongs to a family of highly functionalized diketopiperazine (DKP) alkaloids and bears a unique O-bridged bicyclo[4.2.

Unified Biosynthetic Origin of the Benzodipyrrole Subunits in CC-1065.

CC-1065 is the first characterized member of a family of naturally occurring antibiotics including yatakemycin and duocarmycins with exceptionally potent antitumor activity. CC-1065 contains three benzodipyrroles (1a-, 1b-, and 1c-) of which the 1a-subunit is remarkable by being composed of a cyclopropane ring, and the mechanism for the biological formation of benzodipyrrole rings remains elusive. Previously, biosynthetic studies of CC-1065 were limited to radioactively labeled precursor feeding experiments, which showed that tyrosine (Tyr) and serine (Ser) were incorporated into the two benzodipyrrole (1b- and 1c-) subunits via the same mode but that this was different from the key cyclopropabenzodipyrrole (1a-) subunit with N1-C2-C3 derived from Ser.

Hijacking a hydroxyethyl unit from a central metabolic ketose into a nonribosomal peptide assembly line.

Nonribosomal peptide synthetases (NRPSs) usually catalyze the biosynthesis of peptide natural products by sequential selection, activation, and condensation of amino acid precursors. It was reported that some fatty acids, α-ketoacids, and α-hydroxyacids originating from amino acid metabolism as well as polyketide-derived units can also be used by NRPS assembly lines as an alternative to amino acids. Ecteinascidin 743 (ET-743), naphthyridinomycin (NDM), and quinocarcin (QNC) are three important antitumor natural products belonging to the tetrahydroisoquinoline family.

Analysis of YM-216391 biosynthetic gene cluster and improvement of the cyclopeptide production in a heterologous host.

YM-216391, an antitumor natural product, represents a new class of cyclic peptides containing a polyoxazole-thiazole moiety. Herein we describe its gene cluster encoding the biosynthetic paradigm featuring a ribosomally synthesizing precursor peptide followed by a series of novel posttranslational modifications, which include (i) cleavage of both N-terminal leader peptide and C-terminal extension peptide and cyclization in a head-to-tail fashion, (ii) conversion of an L-Ile to D-allo-Ile, and (iii) β-hydroxylation of Phe by a P450 monooxygenase followed by further heterocyclization and oxidation to form a phenyloxazole moiety. The cluster was heterologously expressed in Streptomyces lividans to bypass difficult genetic manipulation.

Insulin increases shedding of syndecan-1 in the serum of patients with type 2 diabetes mellitus.

Aims: To detect the level of serum syndecan-1 of patients with type 2 diabetes.

Methods: Subjects with diabetes were categorized into 4 subgroups, oral-agents, insulin therapy for 12 months. Serum syndecan-1 was detected by ELISA, and potential correlation between syndecan-1 levels and clinical characteristics was analyzed.