Discovery and Biosynthesis of Azabicyclene, a Conserved Nonribosomal Peptide in Pseudomonas aeruginosa

Abstract

Azabicyclene, an azetidine-containing natural product, was identified using quorum-sensing molecules to upregulate expression of a gene cluster highly conserved in the human pathogen Pseudomonas aeruginosa. Mutational studies of the gene cluster revealed essential genes for biosynthesis, including an unusual nonribosomal peptide synthetase. Reconstitution of this enzyme in vitro identified key biosynthetic intermediates. This work demonstrates a useful strategy for discovering quorum-sensing-regulated natural products. It sets the stage for understanding the biosynthesis and bioactivity of azabicyclene.

Draft Genome Sequence of Pseudomonas aeruginosa Strain LMG 1272, an Atypical White Line Reaction Producer

“…P. aeruginosa LMG 1272 carries homologues of pyocin genes S4 and S11 and also a homologue of F-type tailocin gene cluster (10). Genome analysis using antiSMASH 5.0 (11) to identify biosynthetic gene clusters of secondary metabolites revealed the capacity to produce pyoluteorin (12), pyochelin (13), 2-amino-4-methoxy-trans-3butenoic acid (14), and azabicyclene (15). The lack of characteristic CLP biosynthetic genes (16) indicates that a different diffusible factor is involved in the WLR phenotype.…”

Discovery and Biosynthetic Investigation of a New Antibacterial Dehydrated Non‐Ribosomal Tripeptide

“…Although only two peptide bonds are present in 6,t hree condensation domains were observed, suggesting that some of these Cdomains may be involved in unconventional processes.Phylogenetic analysis of Cdomains [23] revealed that, while AlbA-C 1 is an ormaL L-amino acid condensation domain, AlbB-C 2 and C 3 belong to au nique group of C* domains which are also found in the biosynthetic pathways of NPs, such as methoxyvinylglycine, [9] legonmycin, [24] azabicyclene, [8] puwainaphycin, [25] FK228, [26] bleomycin, [27] hassallidin, [28] nodularin [29] and microcystin [30] (Figure 4B). All of these NPs contain either dhAA motifs or motifs derived from dhAA residues.…”

“…[4] Although less common, Dha and Dhb motifs do appear in non-ribosomal peptides (NRPs). Fore xample,t hey are present in the cyclic pentadepsipeptide,p homalide 1, [5] the cycloheptapeptide,[D-Asp 3 ,(Z)-Dhb 7 ]microcystin 2, [6] the blactam antibiotic norcardicin 3, [7] thep yrrolizidine alkaloid azabicyclene 4 [8] and the nonproteinogenic amino acid methoxyvinylglycine 5 [9] ( Figure 1A). In contrast to RiPPs, both (Z)-and (E)-Dhb geometries have been found in NRPs.…”

“…[14] In vitro biosynthetic reconstitution of two NRPS-derived metabolites, azabicyclene 4 and methoxyvinylglycine 5,also suggested that two noncanonical C* domains are likely to be responsible for the formation of cryptic Dha and cis-a,b dehydroglumate intermediates,respectively,inthe corresponding NRPS pathways. [8,9] However,t he formation of Dhb residues in NRPs remains to be determined. This is the particular case for (E)-Dhb residues.U nlike (Z)-Dhb,t he bio-origin of (E)-Dhb is less obvious.I th as raised aq uestion of whether (E)-Dhb residues in NRPs are derived from L-allo-Thr [12] via facile anti-elimination or they directly descend from syn-elimination in which two vicinal substituents (e.g.…”

Coordinated Action of NRPS, Baeyer-Villiger Monooxygenase, and Methyltransferase Ensures the Economical Biosynthesis of Bohemamines in Streptomyces sp. CB02009

“…In fact, no hydroxyl congeners were reported for pyrrolixenamides, lipocyclocarbamates, azetidomonamides or azabicyclene. 34 Taken together, the BMVOs involved in bacterial pyrrolizdine biosynthesis might only involve a remarkable three-step cascade reaction, and the final hydroxylation reaction catalyzed by LgnC might be an exception. 18 Compounds 6 and 7 would be produced by air-oxidation of 5ʹ.…”