scholarly journals Heterologous Expression of a Cryptic Gene Cluster from Streptomyces leeuwenhoekii C34T Yields a Novel Lasso Peptide, Leepeptin

2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Juan Pablo Gomez-Escribano ◽  
Jean Franco Castro ◽  
Valeria Razmilic ◽  
Scott A. Jarmusch ◽  
Gerhard Saalbach ◽  
...  

ABSTRACT Analysis of the genome sequence of Streptomyces leeuwenhoekii C34T identified biosynthetic gene clusters (BGCs) for three different lasso peptides (Lp1, Lp2, and Lp3) which were not known to be made by the strain. Lasso peptides represent relatively new members of the RiPP (ribosomally synthesized and posttranslationally modified peptides) family of natural products and have not been extensively studied. Lp3, whose production could be detected in culture supernatants from S. leeuwenhoekii C34T and after heterologous expression of its BGC in Streptomyces coelicolor, is identical to the previously characterized chaxapeptin. Lp1, whose production could not be detected or achieved heterologously, appears to be identical to a recently identified member of the citrulassin family of lasso peptides. Since production of Lp2 by S. leeuwenhoekii C34T was not observed, its BGC was also expressed in S. coelicolor. The lasso peptide was isolated and its structure confirmed by mass spectrometry and nuclear magnetic resonance analyses, revealing a novel structure that appears to represent a new family of lasso peptides. IMPORTANCE Recent developments in genome sequencing combined with bioinformatic analysis have revealed that actinomycetes contain a plethora of unexpected BGCs and thus have the potential to produce many more natural products than previously thought. This reflects the inability to detect the production of these compounds under laboratory conditions, perhaps through the use of inappropriate growth media or the absence of the environmental cues required to elicit expression of the corresponding BGCs. One approach to overcoming this problem is to circumvent the regulatory mechanisms that control expression of the BGC in its natural host by deploying heterologous expression. The generally compact nature of lasso peptide BGCs makes them particularly amenable to this approach, and, in the example given here, analysis revealed a new member of the lasso peptide family of RiPPs. This approach should be readily applicable to other cryptic lasso peptide gene clusters and would also facilitate the design and production of nonnatural variants by changing the sequence encoding the core peptide, as has been achieved with other classes of RiPPs.

2021 ◽  
Author(s):  
◽  
Luke Stevenson

<p>Antibiotic discovery rates dramatically declined following the “golden age” of the 1940’s to the 1960’s. The platforms that underpinned that age of discovery rested upon laboratory cultivation of a small clade of bacteria, the actinomycetes, primarily isolated from soil environments. Fermentation extracts of these isolated bacteria have provided the majority of antibiotics and anticancer small molecules still used today. By applying modern genetic analysis techniques to these same environmental sources that have previously yielded such success, we can uncover new biosynthetic pathways, and bioactive compounds. The work described in this thesis investigated New Zealand soil metagenomes for this purpose.  Four large metagenome libraries were constructed from the microbiomes of diverse soil environments. These were then interrogated by a functional screening approach in a knockout Escherichia coli strain, to recover a large collection of the biosynthetic gene clusters responsible for bacterial secondary metabolite production. Using different modes of bioinformatic analysis, these gene clusters were demonstrated to have both phylogenetic divergence, and functional difference from bacterial biosynthesis pathways previously discovered from culture based studies.  Two additional biosynthetic pathways were recovered from one of these metagenome libraries, and in each case found to have novel genetic features. These gene clusters were further studied by heterologous expression within Streptomyces albus production hosts. One of these gene clusters produced small aromatic polyketide compounds, the structure of one of which was solved by chemical analytic techniques, and found to be a new chemical entity.  The second gene cluster was demonstrated to have similarity to known aureolic acid biosynthesis gene clusters – a class of potent anticancer natural products. Heterologous expression resulted in the production of many metabolites, two of which were characterised and found to be new members of this chemical class.  The research in this thesis both validates the use of metagenomic analysis for future natural product discovery efforts, and adds to a growing body of evidence that understudied clades of bacteria have an untapped biosynthetic potential that can be accessed by metagenomic methods.</p>


2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Qiang Zhou ◽  
Guang-Cai Luo ◽  
Huizhan Zhang ◽  
Gong-Li Tang

ABSTRACT A number of strategies have been developed to mine novel natural products based on biosynthetic gene clusters and there have been dozens of successful cases facilitated by the development of genomic sequencing. During our study on biosynthesis of the antitumor polyketide kosinostatin (KST), we found that the genome of Micromonospora sp. strain TP-A0468, the producer of KST, contains other potential polyketide gene clusters, with no encoded products detected. Deletion of kst cluster led to abolishment of KST and the enrichment of several new compounds, which were isolated and characterized as 16-demethylrifamycins (referred to here as compounds 3 to 6). Transcriptional analysis demonstrated that the expression of the essential genes related to the biosynthesis of compounds 3 to 6 was comparable to the level in the wild-type and in the kst cluster deletion strain. This indicates that the accumulation of these compounds was due to the redirection of metabolic flux rather than transcriptional activation. Genetic disruption, chemical complementation, and bioinformatic analysis revealed that the production of compounds 3 to 6 was accomplished by cross talk between the two distantly placed polyketide gene clusters pks3 and M-rif. This finding not only enriches the analogue pool and the biosynthetic diversity of rifamycins but also provides an auxiliary strategy for natural product discovery through genome mining in polyketide-producing microorganisms. IMPORTANCE Natural products are essential in the development of novel clinically used drugs. Discovering new natural products and modifying known compounds are still the two main ways to generate new candidates. Here, we have discovered several rifamycins with varied skeleton structures by redirecting the metabolic flux from the predominant polyketide biosynthetic pathway to the rifamycin pathway in the marine actinomycetes species Micromonospora sp. strain TP-A0468. Rifamycins are indispensable chemotherapeutics in the treatment of various diseases such as tuberculosis, leprosy, and AIDS-related mycobacterial infections. This study exemplifies a useful method for the discovery of cryptic natural products in genome-sequenced microbes. Moreover, the 16-demethylrifamycins and their genetically manipulable producer provide a new opportunity in the construction of novel rifamycin derivates to aid in the defense against the ever-growing drug resistance of Mycobacterium tuberculosis.


2021 ◽  
Author(s):  
◽  
Luke Stevenson

<p>Antibiotic discovery rates dramatically declined following the “golden age” of the 1940’s to the 1960’s. The platforms that underpinned that age of discovery rested upon laboratory cultivation of a small clade of bacteria, the actinomycetes, primarily isolated from soil environments. Fermentation extracts of these isolated bacteria have provided the majority of antibiotics and anticancer small molecules still used today. By applying modern genetic analysis techniques to these same environmental sources that have previously yielded such success, we can uncover new biosynthetic pathways, and bioactive compounds. The work described in this thesis investigated New Zealand soil metagenomes for this purpose.  Four large metagenome libraries were constructed from the microbiomes of diverse soil environments. These were then interrogated by a functional screening approach in a knockout Escherichia coli strain, to recover a large collection of the biosynthetic gene clusters responsible for bacterial secondary metabolite production. Using different modes of bioinformatic analysis, these gene clusters were demonstrated to have both phylogenetic divergence, and functional difference from bacterial biosynthesis pathways previously discovered from culture based studies.  Two additional biosynthetic pathways were recovered from one of these metagenome libraries, and in each case found to have novel genetic features. These gene clusters were further studied by heterologous expression within Streptomyces albus production hosts. One of these gene clusters produced small aromatic polyketide compounds, the structure of one of which was solved by chemical analytic techniques, and found to be a new chemical entity.  The second gene cluster was demonstrated to have similarity to known aureolic acid biosynthesis gene clusters – a class of potent anticancer natural products. Heterologous expression resulted in the production of many metabolites, two of which were characterised and found to be new members of this chemical class.  The research in this thesis both validates the use of metagenomic analysis for future natural product discovery efforts, and adds to a growing body of evidence that understudied clades of bacteria have an untapped biosynthetic potential that can be accessed by metagenomic methods.</p>


2021 ◽  
Author(s):  
Li Cao ◽  
Moshe Beiser ◽  
Joseph D Koos ◽  
Margarita Orlova ◽  
Hader E Elashal ◽  
...  

Lasso peptides are a family of ribosomally synthesized and post-translationally modified peptides (RiPPs) defined by their threaded structure. Besides the class-defining isopeptide bond, other post-translational modifications (PTMs) that further tailor lasso peptides have been previously reported. Using genome mining tools, we identified a subset of lasso peptide biosynthetic gene clusters (BGCs) that are colocalized with protein L-isoaspartyl methyltransferase (PIMT) homologs. PIMTs have an important role in protein repair, restoring isoaspartate residues formed from asparagine deamidation to aspartate. Here we report a new function for PIMT enzymes in the post-translational modification of lasso peptides. The PIMTs associated with lasso peptide BGCs first methylate an L-aspartate sidechain found within the ring of the lasso peptide. The methyl ester is then converted into a stable aspartimide moiety, endowing the lasso peptide ring with rigidity relative to its unmodified counterpart. We describe the heterologous expression and structural characterization of two examples of aspartimide-modified lasso peptides from thermophilic Gram-positive bacteria. The lasso peptide cellulonodin-2 is encoded in the genome of actinobacterium Thermobifida cellulosilytica, while lihuanodin is encoded in the genome of firmicute Lihuaxuella thermophila. Additional genome mining revealed PIMT-containing lasso peptide BGCs in 48 organisms. In addition to heterologous expression, we have reconstituted PIMT-mediated aspartimide formation in vitro, showing that lasso peptide-associated PIMTs transfer methyl groups very rapidly as compared to canonical PIMTs. Furthermore, in stark contrast to other characterized lasso peptide PTMs, the methyltransferase functions only on lassoed substrates.


2011 ◽  
Vol 77 (11) ◽  
pp. 3617-3625 ◽  
Author(s):  
Daniel W. Udwary ◽  
Erin A. Gontang ◽  
Adam C. Jones ◽  
Carla S. Jones ◽  
Andrew W. Schultz ◽  
...  

ABSTRACTBacteria of the genusFrankiaare mycelium-forming actinomycetes that are found as nitrogen-fixing facultative symbionts of actinorhizal plants. Although soil-dwelling actinomycetes are well-known producers of bioactive compounds, the genusFrankiahas largely gone uninvestigated for this potential. Bioinformatic analysis of the genome sequences ofFrankiastrains ACN14a, CcI3, and EAN1pec revealed an unexpected number of secondary metabolic biosynthesis gene clusters. Our analysis led to the identification of at least 65 biosynthetic gene clusters, the vast majority of which appear to be unique and for which products have not been observed or characterized. More than 25 secondary metabolite structures or structure fragments were predicted, and these are expected to include cyclic peptides, siderophores, pigments, signaling molecules, and specialized lipids. Outside the hopanoid gene locus, no cluster could be convincingly demonstrated to be responsible for the few secondary metabolites previously isolated from otherFrankiastrains. Few clusters were shared among the three species, demonstrating species-specific biosynthetic diversity. Proteomic analysis ofFrankiasp. strains CcI3 and EAN1pec showed that significant and diverse secondary metabolic activity was expressed in laboratory cultures. In addition, several prominent signals in the mass range of peptide natural products were observed inFrankiasp. CcI3 by intact-cell matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). This work supports the value of bioinformatic investigation in natural products biosynthesis using genomic information and presents a clear roadmap for natural products discovery in theFrankiagenus.


2019 ◽  
Author(s):  
Snorre Sulheim ◽  
Tjaša Kumelj ◽  
Dino van Dissel ◽  
Ali Salehzadeh-Yazdi ◽  
Chao Du ◽  
...  

AbstractMany biosynthetic gene clusters (BGCs) require heterologous expression to realize their genetic potential, including silent and metagenomic BGCs. Although the engineered Streptomyces coelicolor M1152 is a widely used host for heterologous expression of BGCs, a systemic understanding of how its genetic modifications affect the metabolism is lacking and limiting further development. We performed a comparative analysis of M1152 and its ancestor M145, connecting information from proteomics, transcriptomics, and cultivation data into a comprehensive picture of the metabolic differences between these strains. Instrumental to this comparison was the application of an improved consensus genome-scale metabolic model (GEM) of S. coelicolor. Although many metabolic patterns are retained in M1152, we find that this strain suffers from oxidative stress, possibly caused by increased oxidative metabolism. Furthermore, precursor availability is likely not limiting polyketide production, implying that other strategies could be beneficial for further development of S. coelicolor for heterologous production of novel compounds.


Biopolymers ◽  
2010 ◽  
Vol 93 (9) ◽  
pp. 823-832 ◽  
Author(s):  
Katrin Flinspach ◽  
Lucia Westrich ◽  
Leonard Kaysser ◽  
Stefanie Siebenberg ◽  
Juan Pablo Gomez-Escribano ◽  
...  

2016 ◽  
Vol 82 (19) ◽  
pp. 5795-5805 ◽  
Author(s):  
Min Xu ◽  
Yemin Wang ◽  
Zhilong Zhao ◽  
Guixi Gao ◽  
Sheng-Xiong Huang ◽  
...  

ABSTRACTGenome sequencing projects in the last decade revealed numerous cryptic biosynthetic pathways for unknown secondary metabolites in microbes, revitalizing drug discovery from microbial metabolites by approaches called genome mining. In this work, we developed a heterologous expression and functional screening approach for genome mining from genomic bacterial artificial chromosome (BAC) libraries inStreptomycesspp. We demonstrate mining from a strain ofStreptomyces rochei, which is known to produce streptothricins and borrelidin, by expressing its BAC library in the surrogate hostStreptomyces lividansSBT5, and screening for antimicrobial activity. In addition to the successful capture of the streptothricin and borrelidin biosynthetic gene clusters, we discovered two novel linear lipopeptides and their corresponding biosynthetic gene cluster, as well as a novel cryptic gene cluster for an unknown antibiotic fromS. rochei. This high-throughput functional genome mining approach can be easily applied to other streptomycetes, and it is very suitable for the large-scale screening of genomic BAC libraries for bioactive natural products and the corresponding biosynthetic pathways.IMPORTANCEMicrobial genomes encode numerous cryptic biosynthetic gene clusters for unknown small metabolites with potential biological activities. Several genome mining approaches have been developed to activate and bring these cryptic metabolites to biological tests for future drug discovery. Previous sequence-guided procedures relied on bioinformatic analysis to predict potentially interesting biosynthetic gene clusters. In this study, we describe an efficient approach based on heterologous expression and functional screening of a whole-genome library for the mining of bioactive metabolites fromStreptomyces. The usefulness of this function-driven approach was demonstrated by the capture of four large biosynthetic gene clusters for metabolites of various chemical types, including streptothricins, borrelidin, two novel lipopeptides, and one unknown antibiotic fromStreptomyces rocheiSal35. The transfer, expression, and screening of the library were all performed in a high-throughput way, so that this approach is scalable and adaptable to industrial automation for next-generation antibiotic discovery.


2016 ◽  
Vol 12 (4) ◽  
pp. 1106-1109 ◽  
Author(s):  
Julian D. Hegemann ◽  
Christopher D. Fage ◽  
Shaozhou Zhu ◽  
Klaus Harms ◽  
Francesco Saverio Di Leva ◽  
...  

Lasso peptides are fascinating natural products with a unique structural fold that can exhibit tremendous thermal stability.


2015 ◽  
Vol 81 (13) ◽  
pp. 4339-4350 ◽  
Author(s):  
Qi Zhang ◽  
James R. Doroghazi ◽  
Xiling Zhao ◽  
Mark C. Walker ◽  
Wilfred A. van der Donk

ABSTRACTLanthionine-containing peptides (lanthipeptides) are a rapidly growing family of polycyclic peptide natural products belonging to the large class of ribosomally synthesized and posttranslationally modified peptides (RiPPs). Lanthipeptides are widely distributed in taxonomically distant species, and their currently known biosynthetic systems and biological activities are diverse. Building on the recent natural product gene cluster family (GCF) project, we report here large-scale analysis of lanthipeptide-like biosynthetic gene clusters fromActinobacteria. Our analysis suggests that lanthipeptide biosynthetic pathways, and by extrapolation the natural products themselves, are much more diverse than currently appreciated and contain many different posttranslational modifications. Furthermore, lanthionine synthetases are much more diverse in sequence and domain topology than currently characterized systems, and they are used by the biosynthetic machineries for natural products other than lanthipeptides. The gene cluster families described here significantly expand the chemical diversity and biosynthetic repertoire of lanthionine-related natural products. Biosynthesis of these novel natural products likely involves unusual and unprecedented biochemistries, as illustrated by several examples discussed in this study. In addition, class IV lanthipeptide gene clusters are shown not to be silent, setting the stage to investigate their biological activities.


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