Bacteria provide a rich source of natural products with potential therapeutic applications, such as novel antibiotic classes or anticancer drugs. Bioactivity-guided screening of bacterial extracts ...and characterization of biosynthetic pathways for drug discovery is now complemented by the availability of large (meta)genomic collections, placing researchers into the postgenomic, big-data era. The progress in next-generation sequencing and the rise of powerful computational tools provide unprecedented insights into unexplored taxa, ecological niches and 'biosynthetic dark matter', revealing diverse and chemically distinct natural products in previously unstudied bacteria. In this Review, we discuss such sources of new chemical entities and the implications for drug discovery with a particular focus on the strategies that have emerged in recent years to identify and access novelty.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Covering: up to 2021
Metagenomics has yielded massive amounts of sequencing data offering a glimpse into the biosynthetic potential of the uncultivated microbial majority. While genome-resolved ...information about microbial communities from nearly every environment on earth is now available, the ability to accurately predict biocatalytic functions directly from sequencing data remains challenging. Compared to primary metabolic pathways, enzymes involved in secondary metabolism often catalyze specialized reactions with diverse substrates, making these pathways rich resources for the discovery of new enzymology. To date, functional insights gained from studies on environmental DNA (eDNA) have largely relied on PCR- or activity-based screening of eDNA fragments cloned in fosmid or cosmid libraries. As an alternative, shotgun metagenomics holds underexplored potential for the discovery of new enzymes directly from eDNA by avoiding common biases introduced through PCR- or activity-guided functional metagenomics workflows. However, inferring new enzyme functions directly from eDNA is similar to searching for a 'needle in a haystack' without direct links between genotype and phenotype. The goal of this review is to provide a roadmap to navigate shotgun metagenomic sequencing data and identify new candidate biosynthetic enzymes. We cover both computational and experimental strategies to mine metagenomes and explore protein sequence space with a spotlight on natural product biosynthesis. Specifically, we compare
in silico
methods for enzyme discovery including phylogenetics, sequence similarity networks, genomic context, 3D structure-based approaches, and machine learning techniques. We also discuss various experimental strategies to test computational predictions including heterologous expression and screening. Finally, we provide an outlook for future directions in the field with an emphasis on meta-omics, single-cell genomics, cell-free expression systems, and sequence-independent methods.
Shotgun metagenomic approaches to uncover new enzymes are underdeveloped relative to PCR- or activity-based functional metagenomics. Here we review computational and experimental strategies to discover biosynthetic enzymes from metagenomes.
Covering 2000 to June 2015
This review discusses the biosynthesis of natural products that are generated by
trans
-AT polyketide synthases, a family of catalytically versatile enzymes that represents ...one of the major group of proteins involved in the production of bioactive polyketides. The article includes 609 references and covers the literature from 2009 through June 2015.
This review discusses the biosynthesis of natural products that are generated by
trans
-AT polyketide synthases, a family of catalytically versatile enzymes that represents one of the major group of proteins involved in the production of bioactive polyketides.
Many drug candidates from marine and terrestrial invertebrates are suspected metabolites of uncultured bacterial symbionts. The antitumor polyketides of the pederin family, isolated from beetles and ...sponges, are an example. Drug development from such sources is commonly hampered by low yields and the difficulty of sustaining invertebrate cultures. To obtain insight into the true producer and find alternative supplies of these rare drug candidates, the putative pederin biosynthesis genes were cloned from total DNA of Paederus fuscipes beetles, which use this compound for chemical defense. Sequence analysis of the gene cluster and adjacent regions revealed the presence of ORFs with typical bacterial architecture and homologies. The ped cluster, which is present only in beetle specimens with high pederin content, is located on a 54-kb region bordered by transposase pseudogenes and encodes a mixed modular polyketide synthase/nonribosomal peptide synthetase. Notably, none of the modules contains regions with homology to acyltransferase domains, but two copies of isolated monodomain acyltransferase genes were found at the upstream end of the cluster. In line with an involvement in pederin biosynthesis, the upstream cluster region perfectly mirrors pederin structure. The unexpected presence of additional polyketide synthase/nonribosomal peptide synthetase modules reveals surprising insights into the evolutionary relationship between pederin-type pathways in beetles and sponges.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
The wide range of moieties installed in ribosomally synthesized and post‐translationally modified peptides (RiPPs) suggests largely untapped potential for protein engineering. However, many RiPP ...maturases recognize target peptide precursors through an N‐terminal leader sequence that is challenging to adapt to proteins. We have recently reported a family of enzymes that splice XYG sites in RiPPs to install α‐keto‐β‐amino acids. Backbone modifications influence diverse protein properties, yet the toolkit to install β‐amino acids is limited. Here we report their leader‐independent incorporation into proteins in E. coli. Integrating an 11‐residue splice tag into six different proteins permitted the site‐selective introduction of β‐residues in vivo. The motif fusion at C‐, N‐terminal, and internal positions yielded various β‐residues. Our approach complements the few existing methods to introduce β‐amino acids or ketone‐bearing moieties, suggesting diverse applications in chemical biology.
A natural non‐canonical peptide splicing reaction was repurposed to achieve incorporation of various β‐amino acids (α‐keto‐β‐amino acid residues) at C‐ or N‐terminal or internal positions of proteins. The protein backbone modification is carried out by a recently discovered family of peptide‐modifying radical S‐adenosyl‐l‐methionine enzymes in E. coli, suggesting diverse applications in chemical biology.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Marine sponges (phylum Porifera) often contain dense and diverse microbial communities, which can constitute up to 35% of the sponge biomass. The genome of one sponge, Amphimedon queenslandica, was ...recently sequenced, and this has provided new insights into the origins of animal evolution. Complementary efforts to sequence the genomes of uncultivated sponge symbionts have yielded the first glimpse of how these intimate partnerships are formed. The remarkable microbial and chemical diversity of the sponge-microorganism association, coupled with its postulated antiquity, makes sponges important model systems for the study of metazoan host-microorganism interactions, and their evolution, as well as for enabling access to biotechnologically important symbiont-derived natural products. In this Review, we discuss our current understanding of the interactions between marine sponges and their microbial symbiotic consortia, and highlight recent insights into these relationships from genomic studies.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Bacterial natural products display astounding structural diversity, which, in turn, endows them with a remarkable range of biological activities that are of significant value to modern society. Such ...structural features are generated by biosynthetic enzymes that construct core scaffolds or perform peripheral modifications, and can thus define natural product families, introduce pharmacophores and permit metabolic diversification. Modern genomics approaches have greatly enhanced our ability to access and characterize natural product pathways via sequence-similarity-based bioinformatics discovery strategies. However, many biosynthetic enzymes catalyse exceptional, unprecedented transformations that continue to defy functional prediction and remain hidden from us in bacterial (meta)genomic sequence data. In this Review, we highlight exciting examples of unusual enzymology that have been uncovered recently in the context of natural product biosynthesis. These suggest that much of the natural product diversity, including entire substance classes, awaits discovery. New approaches to lift the veil on the cryptic chemistries of the natural product universe are also discussed.
Abstract
The Asian citrus psyllid Diaphorina citri (Insecta: Hemiptera: Psylloidea), a serious pest of citrus species worldwide, harbors vertically transmitted intracellular mutualists, Candidatus ...Profftella armatura (Profftella_DC, Gammaproteobacteria: Burkholderiales) and Candidatus Carsonella ruddii (Carsonella_DC, Gammaproteobacteria: Oceanospirillales). Whereas Carsonella_DC is a typical nutritional symbiont, Profftella_DC is a unique defensive symbiont with organelle-like features, including intracellular localization within the host, perfect infection in host populations, vertical transmission over evolutionary time, and drastic genome reduction down to much less than 1 Mb. Large parts of the 460-kb genome of Profftella_DC are devoted to genes for synthesizing a polyketide toxin; diaphorin. To better understand the evolution of this unusual symbiont, the present study analyzed the genome of Profftella_Dco, a sister lineage to Profftella_DC, using Diaphorina cf. continua, a host psyllid congeneric with D. citri. The genome of coresiding Carsonella (Carsonella_Dco) was also analyzed. The analysis revealed nearly perfect synteny conservation in these genomes with their counterparts from D. citri. The substitution rate analysis further demonstrated genomic stability of Profftella which is comparable to that of Carsonella. Profftella_Dco and Profftella_DC shared all genes for the biosynthesis of diaphorin, hemolysin, riboflavin, biotin, and carotenoids, underlining multiple roles of Profftella, which may contribute to stabilizing symbiotic relationships with the host. However, acyl carrier proteins were extensively amplified in polyketide synthases DipP and DipT for diaphorin synthesis in Profftella_Dco. This level of acyl carrier protein augmentation, unprecedented in modular polyketide synthases of any known organism, is not thought to influence the polyketide structure but may improve the synthesis efficiency.
An analysis of cyanobacterial genomes revealed an architecturally unique biosynthetic gene cluster with an unusually high number of genes encoding predicted iron(II)/α-ketoglutarate-dependent ...halogenases. Mass spectrometry-guided identification of the corresponding metabolites yielded the aranazoles, extensively halogenated nonribosomal peptide–polyketide hybrids. Their chlorine-bearing fatty acyl-like moiety is reminiscent of the hyperhalogenated chlorosulfolipids, natural products of unknown enzymatic origin that were previously isolated from eukaryotic algae and mussels.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
PDF
