Publications

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2018
Reynolds, KA, Luhavaya H, Li J, Dahesh S, Nizet V, Yamanaka K, Moore BS.  2018.  Isolation and structure elucidation of lipopeptide antibiotic taromycin B from the activated taromycin biosynthetic gene cluster. Journal of Antibiotics. 71:333-338.   10.1038/ja.2017.146   AbstractWebsite

In the ongoing effort to unlock the chemical potential of marine bacteria, genetic engineering of biosynthetic gene clusters (BGCs) is increasingly used to awake or improve expression of biosynthetic genes that may lead to discovery of novel bioactive natural products. Previously, we reported the successful capture, engineering and heterologous expression of an orphan BGC from the marine actinomycete Saccharomonospora sp. CNQ-490, which resulted in the isolation of the novel lipopeptide antibiotic taromycin A. Herein we report the isolation and structure elucidation of taromycin B, the second most abundant product of the taromycin biosynthetic series, and show that taromycins A and B exhibit complex chromatographic properties indicative of interconverting conformations. Taromycins A and B display potent activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium clinical isolates, suggestive that the taromycin molecular scaffold is a promising starting point for further derivatization to produce compounds with promising antibiotic characteristics.

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.

2013
Lane, AL, Nam SJ, Fukuda T, Yamanaka K, Kauffman CA, Jensen PR, Fenical W, Moore BS.  2013.  Structures and Comparative Characterization of Biosynthetic Gene Clusters for Cyanosporasides, Enediyne-Derived Natural Products from Marine Actinomycetes. Journal of the American Chemical Society. 135:4171-4174.   10.1021/ja311065v   AbstractWebsite

Cyanosporasides are marine bacterial natural products containing a chlorinated cyclopenta[a]indene core of suspected enediyne polyketide biosynthetic origin. Herein, we report the isolation and characterization of novel cyanosporasides C-F (3-6) from the marine actinomycetes Salinispora pacifica CNS-143 and Streptomyces sp. CNT-179, highlighted by the unprecedented C-2' N-acetylcysteamine functionalized hexose group of 6. Cloning, sequencing, and mutagenesis of homologous similar to 50 kb cyanosporaside biosynthetic gene clusters from both bacteria afforded the first genetic evidence supporting cyanosporaside's enediyne, and thereby p-benzyne biradical, biosynthetic origin and revealed the molecular basis for nitrile and glycosyl functionalization. This study provides new opportunities for bioengineering of enediyne derivatives and expands the structural diversity afforded by enediyne gene clusters.

Horsman, GP, Lechner A, Ohnish Y, Moore BS, Shen B.  2013.  Predictive model for epoxide hydrolase-generated stereochemistry in the biosynthesis of nine-membered enediyne antitumor antibiotics. Biochemistry. 52:5217-5224.   10.1021/bi400572a   AbstractWebsite

Nine-membered enediyne antitumor antibiotics C-1027, neocarzinostatin (NCS), and kedarcidin (KED) possess enediyne cores to which activity-modulating peripheral moieties are attached via (R)- or (S)-vicinal diols. We have previously shown that this stereochemical difference arises from hydrolysis of epoxide precursors by epoxide hydrolases (EHs) with different regioselectivities. The inverting EHs, such as SgcF, hydrolyze an (S)-epoxide substrate to yield an (R)-diol in C-1027 biosynthesis, whereas the retaining EHs, such as NcsF2 and KedF, hydrolyze an (S)-epoxide substrate to yield an (S)-diol in NCS and KED biosynthesis. We now report the characterization of a series of EH mutants and provide a predictive model for EH regioselectivity in the biosynthesis of the nine-membered enediyne antitumor antibiotics. A W236Y mutation in SgcF increased the retaining activity toward (S)-styrene oxide by 3-fold, and a W236Y/Q237M double mutation in SgcF, mimicking NcsF2 and KedF, resulted in a 20-fold increase in the retaining activity. To test the predictive utility of these mutations, two putative enediyne biosynthesis-associated EHs were identified by genome mining and confirmed as inverting enzymes, SpoF from Salinospora tropica CNB-440 and SgrF (SGR_625) from Streptomyces griseus IFO 13350. Finally, phylogenetic analysis of EHs revealed a familial classification according to inverting versus retaining activity. Taken together, these results provide a predictive model for vicinal diol stereochemistry in enediyne biosynthesis and set the stage for further elucidating the origins of EH regioselectivity.