Publications

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2019
Bauman, KD, Li J, Murata K, Mantovani SM, Dahesh S, Nizet V, Luhavaya H, Moore BS.  2019.  Refactoring the cryptic streptophenazine biosynthetic gene cluster unites phenazine, polyketide, and nonribosomal peptide biochemistry. Cell Chemical Biology. 26:724-+.   10.1016/j.chembiol.2019.02.004   AbstractWebsite

The disconnect between the genomic prediction of secondary metabolite biosynthetic potential and the observed laboratory production profile of microorganisms is well documented. While heterologous expression of biosynthetic gene clusters (BGCs) is often seen as a potential solution to bridge this gap, it is not immune to many challenges including impaired regulation, the inability to recruit essential building blocks, and transcriptional and/or translational silence of the biosynthetic genes. Here we report the discovery, cloning, refactoring, and heterologous expression of a cryptic hybrid phenazine-type BGC (spz) from the marine actinomycete Streptomyces sp. CNB-091. Overexpression of the engineered spz pathway resulted in increased production and chemical diversity of phenazine natural products belonging to the streptophenazine family, including bioactive members containing an unprecedented N-formylglycine attachment. An atypical discrete adenylation enzyme in the spz cluster is required to introduce the formylglycine moiety and represents a phylogenetically distinct class of adenylation proteins.

2018
Zhang, JJ, Moore BS, Tang XY.  2018.  Engineering Salinispora tropica for heterologous expression of natural product biosynthetic gene clusters. Applied Microbiology and Biotechnology. 102:8437-8446.   10.1007/s00253-018-9283-z   AbstractWebsite

The marine actinomycete genus Salinispora is a remarkably prolific source of structurally diverse and biologically active secondary metabolites. Herein, we select the model organism Salinispora tropica CNB-440 for development as a heterologous host for the expression of biosynthetic gene clusters (BGCs) to complement well-established Streptomyces host strains. In order to create an integratable host with a clean background of secondary metabolism, we replaced three genes (salA-C) essential for salinosporamide biosynthesis with a cassette containing the Streptomyces coelicolor Phi C31 phage attachment site attB to generate the mutant S. tropica CNB-4401 via double-crossover recombination. This mutagenesis not only knocks-in the attachment site attB in the genome of S. tropica CNB-440 but also abolishes production of the salinosporamides, thereby simplifying the strain's chemical background. We validated this new heterologous host with the successful integration and expression of the thiolactomycin BGC that we recently identified in several S. pacifica strains. When compared to the extensively engineered superhost S. coelicolor M1152, the production of thiolactomycins from S. tropica CNB-4401 was approximately 3-fold higher. To the best of our knowledge, this is the first example of using a marine actinomycete as a heterologous host for natural product BGC expression. The established heterologous host may provide a useful platform to accelerate the discovery of novel natural products and engineer biosynthetic pathways.

2016
Jordan, PA, Moore BS.  2016.  Biosynthetic pathway connects cryptic ribosomally synthesized posttranslationally modified peptide genes with pyrroloquinoline alkaloids. Cell Chemical Biology. 23:1504-1514.   10.1016/j.chembiol.2016.10.009   AbstractWebsite

In an era where natural product biosynthetic gene clusters can be rapidly identified from sequenced genomes, it is unusual for the biosynthesis of an entire natural product class to remain unknown. Yet, the genetic determinates for pyrroloquinoline alkaloid biosynthesis have remained obscure despite their abundance and deceptive structural simplicity. In this work, we have identified the biosynthetic gene cluster for ammosamides A-C, pyrroloquinoline alkaloids from Streptomyces sp. CNR-698. Through direct cloning, heterologous expression and gene deletions we have validated the ammosamide biosynthetic gene cluster and demonstrated that these seemingly simple molecules are derived from a surprisingly complex set of biosynthetic genes that are also found in the biosynthesis of lymphostin, a structurally related pyrroloquinoline alkaloid from Salinispora and Streptomyces. Our results implicate a conserved set of genes driving pyrroloquinoline biosynthesis that consist of genes frequently associated with ribosomal peptide natural product biosynthesis, and whose exact biochemical role remains enigmatic.

2015
Tang, XY, Li J, Millan-Aguinaga N, Zhang JJ, O'Neill EC, Ugalde JA, Jensen PR, Mantovani SM, Moore BS.  2015.  Identification of thiotetronic acid antibiotic biosynthetic pathways by target-directed genome mining. Acs Chemical Biology. 10:2841-2849.   10.1021/acschembio.5b00658   AbstractWebsite

Recent genome sequencing efforts have led to the rapid accumulation of uncharacterized or "orphaned" secondary metabolic biosynthesis gene clusters (BGCs) in public databases. This increase in DNA-sequenced big data has given rise to significant challenges in the applied field of natural product genome mining, including (i) how to prioritize the characterization of orphan BGCs and (ii) how to rapidly connect genes to biosynthesized small molecules. Here, we show that by correlating putative antibiotic resistance genes that encode target-modified proteins with orphan BGCs, we predict the biological function of pathway specific small molecules before they have been revealed in a process we call target-directed genome mining. By querying the pan-genome of 86 Salinispora bacterial genomes for duplicated house-keeping genes colocalized with natural product BGCs, we prioritized an orphan polyketide synthase-nonribosomal peptide synthetase hybrid BGC (tlm) with a putative fatty acid synthase resistance gene. We employed a new synthetic double-stranded DNA-mediated cloning strategy based on transformation-associated recombination to efficiently capture tlm and the related Mu BGCs directly from genomic DNA and to heterologously express them in Streptomyces hosts. We show the production of a group of unusual thiotetronic acid natural products, including the well-known fatty acid synthase inhibitor thiolactomycin that was first described over 30 years ago, yet never at the genetic level in regards to biosynthesis and autoresistance. This finding not only validates the target-directed genome mining strategy for the discovery of antibiotic producing gene clusters without a priori knowledge of the molecule synthesized but also paves the way for the investigation of novel: enzymology involved in thiotetronic, acid natural product biosynthesis.

Kim, E, Moore BS, Yoon YJ.  2015.  Reinvigorating natural product combinatorial biosynthesis with synthetic biology. Nature Chemical Biology. 11:649-659.   10.1038/nchembio.1893   AbstractWebsite

Natural products continue to play a pivotal role in drug-discovery efforts and in the understanding if human health. The ability to extend nature's chemistry through combinatorial biosynthesis-altering functional groups, regiochemistry and scaffold backbones through the manipulation of biosynthetic enzymes-offers unique opportunities to create natural product analogs. Incorporating emerging synthetic biology techniques has the potential to further accelerate the refinement of combinatorial biosynthesis as a robust platform for the diversification of natural chemical drug leads. Two decades after the field originated, we discuss the current limitations, the realities and the state of the art of combinatorial biosynthesis, including the engineering of substrate specificity of biosynthetic enzymes and the development of heterologous expression systems for biosynthetic pathways. We also propose a new perspective for the combinatorial biosynthesis of natural products that could reinvigorate drug discovery by using synthetic biology in combination with synthetic chemistry.

Duncan, KR, Crusemann M, Lechner A, Sarkar A, Li J, Ziemert N, Wang MX, Bandeira N, Moore BS, Dorrestein PC, Jensen PR.  2015.  Molecular networking and pattern-based genome mining improves discovery of biosynthetic gene clusters and their products from Salinispora species. Chemistry & Biology. 22:460-471.   10.1016/j.chembiol.2015.03.010   AbstractWebsite

Genome sequencing has revealed that bacteria contain many more biosynthetic gene clusters than predicted based on the number of secondary metabolites discovered to date. While this biosynthetic reservoir has fostered interest in new tools for natural product discovery, there remains a gap between gene cluster detection and compound discovery. Here we apply molecular networking and the new concept of pattern-based genome mining to 35 Salinispora strains, including 30 for which draft genome sequences were either available or obtained for this study. The results provide a method to simultaneously compare large numbers of complex microbial extracts, which facilitated the identification of media components, known compounds and their derivatives, and new compounds that could be prioritized for structure elucidation. These efforts revealed considerable metabolite diversity and led to several molecular family-gene cluster pairings, of which the quinomycin-type depsipeptide retimycin A was characterized and linked to gene cluster NRPS40 using pattern-based bioinformatic approaches.

2014
Yamanaka, K, Reynolds KA, Kersten RD, Ryan KS, Gonzalez DJ, Nizet V, Dorrestein PC, Moore BS.  2014.  Direct cloning and refactoring of a silent lipopeptide biosynthetic gene cluster yields the antibiotic taromycin A. Proceedings of the National Academy of Sciences of the United States of America. 111:1957-1962.   10.1073/pnas.1319584111   AbstractWebsite

Recent developments in next-generation sequencing technologies have brought recognition of microbial genomes as a rich resource for novel natural product discovery. However, owing to the scarcity of efficient procedures to connect genes to molecules, only a small fraction of secondary metabolomes have been investigated to date. Transformation-associated recombination (TAR) cloning takes advantage of the natural in vivo homologous recombination of Saccharomyces cerevisiae to directly capture large genomic loci. Here we report a TAR-based genetic platform that allows us to directly clone, refactor, and heterologously express a silent biosynthetic pathway to yield a new antibiotic. With this method, which involves regulatory gene remodeling, we successfully expressed a 67-kb nonribosomal peptide synthetase biosynthetic gene cluster from the marine actinomycete Saccharomonospora sp. CNQ-490 and produced the dichlorinated lipopeptide antibiotic taromycin A in the model expression host Streptomyces coelicolor. The taromycin gene cluster (tar) is highly similar to the clinically approved antibiotic daptomycin from Streptomyces roseosporus, but has notable structural differences in three amino acid residues and the lipid side chain. With the activation of the tar gene cluster and production of taromycin A, this study highlights a unique "plug-and-play" approach to efficiently gaining access to orphan pathways that may open avenues for novel natural product discoveries and drug development.

2011
Kersten, RD, Yang YL, Xu YQ, Cimermancic P, Nam SJ, Fenical W, Fischbach MA, Moore BS, Dorrestein PC.  2011.  A mass spectrometry-guided genome mining approach for natural product peptidogenomics. Nature Chemical Biology. 7:794-802.   10.1038/nchembio.684   AbstractWebsite

Peptide natural products show broad biological properties and are commonly produced by orthogonal ribosomal and nonribosomal pathways in prokaryotes and eukaryotes. To harvest this large and diverse resource of bioactive molecules, we introduce here natural product peptidogenomics (NPP), a new MS-guided genome-mining method that connects the chemotypes of peptide natural products to their biosynthetic gene clusters by iteratively matching de novo tandem MS (MS(n)) structures to genomics-based structures following biosynthetic logic. In this study, we show that NPP enabled the rapid characterization of over ten chemically diverse ribosomal and nonribosomal peptide natural products of previously unidentified composition from Streptomycete bacteria as a proof of concept to begin automating the genome-mining process. We show the identification of lantipeptides, lasso peptides, linardins, formylated peptides and lipopeptides, many of which are from well-characterized model Streptomycetes, highlighting the power of NPP in the discovery of new peptide natural products from even intensely studied organisms.

Lechner, A, Eustaquio AS, Gulder TAM, Hafner M, Moore BS.  2011.  Selective Overproduction of the Proteasome Inhibitor Salinosporamide A via Precursor Pathway Regulation. Chemistry & Biology. 18:1527-1536.   10.1016/j.chembiol.2011.10.014   AbstractWebsite

The chlorinated natural product salinosporamide A is a potent 20S proteasome inhibitor currently in clinical trials as an anticancer agent. To deepen our understanding of salinosporamide biosynthesis, we investigated the function of a LuxR-type pathway-specific regulatory gene, salR2, and observed a selective effect on the production of salinosporamide A over its less active aliphatic analogs. SalR2 specifically activates genes involved in the biosynthesis of the halogenated precursor chloroethylmalonyl-CoA, which is a dedicated precursor of salinosporamide A. Specifically, SalR2 activates transcription of two divergent operons-one of which contains the unique S-adenosyl-L-methionine-dependent chlorinase encoding gene salL. By applying this knowledge to rational engineering, we were able to selectively double salinosporamide A production. This study exemplifies the specialized regulation of a polyketide precursor pathway and its application to the selective overproduction of a specific natural product congener.

2009
Penn, K, Jenkins C, Nett M, Udwary DW, Gontang EA, McGlinchey RP, Foster B, Lapidus A, Podell S, Allen EE, Moore BS, Jensen PR.  2009.  Genomic islands link secondary metabolism to functional adaptation in marine Actinobacteria. Isme Journal. 3:1193-1203.   10.1038/ismej.2009.58   AbstractWebsite

Genomic islands have been shown to harbor functional traits that differentiate ecologically distinct populations of environmental bacteria. A comparative analysis of the complete genome sequences of the marine Actinobacteria Salinispora tropica and Salinispora arenicola reveals that 75% of the species-specific genes are located in 21 genomic islands. These islands are enriched in genes associated with secondary metabolite biosynthesis providing evidence that secondary metabolism is linked to functional adaptation. Secondary metabolism accounts for 8.8% and 10.9% of the genes in the S. tropica and S. arenicola genomes, respectively, and represents the major functional category of annotated genes that differentiates the two species. Genomic islands harbor all 25 of the species-specific biosynthetic pathways, the majority of which occur in S. arenicola and may contribute to the cosmopolitan distribution of this species. Genome evolution is dominated by gene duplication and acquisition, which in the case of secondary metabolism provide immediate opportunities for the production of new bioactive products. Evidence that secondary metabolic pathways are exchanged horizontally, coupled with earlier evidence for fixation among globally distributed populations, supports a functional role and suggests that the acquisition of natural product biosynthetic gene clusters represents a previously unrecognized force driving bacterial diversification. Species-specific differences observed in clustered regularly interspaced short palindromic repeat sequences suggest that S. arenicola may possess a higher level of phage immunity, whereas a highly duplicated family of polymorphic membrane proteins provides evidence for a new mechanism of marine adaptation in Gram-positive bacteria. The ISME Journal (2009) 3, 1193-1203; doi:10.1038/ismej.2009.58; published online 28 May 2009