scholarly journals The Novel Transcriptional Regulator LmbU Promotes Lincomycin Biosynthesis through Regulating Expression of Its Target Genes in Streptomyces lincolnensis

2017 ◽  
Vol 200 (2) ◽  
Author(s):  
Bingbing Hou ◽  
Yanwei Lin ◽  
Haizhen Wu ◽  
Meijin Guo ◽  
Hrvoje Petkovic ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Target Genes ◽  
Regulatory Mechanism ◽  
Transcriptional Regulator ◽  
Gene Clusters ◽  
Saccharopolyspora Erythraea ◽  
Transcriptional Analysis ◽  
Biosynthetic Gene ◽  
Content Type ◽  
Streptomyces Lincolnensis

ABSTRACT Lincomycin A is a clinically important antimicrobial agent produced by Streptomyces lincolnensis . In this study, a new regulator designated LmbU (GenBank accession no. ABX00623.1) was identified and characterized to regulate lincomycin biosynthesis in S. lincolnensis wild-type strain NRRL 2936. Both inactivation and overexpression of lmbU resulted in significant influences on lincomycin production. Transcriptional analysis and in vivo neomycin resistance (Neo r ) reporter assays demonstrated that LmbU activates expression of the lmbA , lmbC , lmbJ , and lmbW genes and represses expression of the lmbK and lmbU genes. Electrophoretic mobility shift assays (EMSAs) demonstrated that LmbU can bind to the regions upstream of the lmbA and lmbW genes through the consensus and palindromic sequence 5′-CGCCGGCG-3′. However, LmbU cannot bind to the regions upstream of the lmbC , lmbJ , lmbK , and lmbU genes as they lack this motif. These data indicate a complex transcriptional regulatory mechanism of LmbU. LmbU homologues are present in the biosynthetic gene clusters of secondary metabolites of many other actinomycetes. Furthermore, the LmbU homologue from Saccharopolyspora erythraea (GenBank accession no. WP_009944629.1) also binds to the regions upstream of lmbA and lmbW , which suggests widespread activity for this regulator. LmbU homologues have no significant structural similarities to other known cluster-situated regulators (CSRs), which indicates that they belong to a new family of regulatory proteins. In conclusion, the present report identifies LmbU as a novel transcriptional regulator and provides new insights into regulation of lincomycin biosynthesis in S. lincolnensis . IMPORTANCE Although lincomycin biosynthesis has been extensively studied, its regulatory mechanism remains elusive. Here, a novel regulator, LmbU, which regulates transcription of its target genes in the lincomycin biosynthetic gene cluster ( lmb gene cluster) and therefore promotes lincomycin biosynthesis, was identified in S. lincolnensis strain NRRL 2936. Importantly, we show that this new regulatory element is relatively widespread across diverse actinomycetes species. In addition, our findings provide a new strategy for improvement of yield of lincomycin through manipulation of LmbU, and this approach could also be evaluated in other secondary metabolite gene clusters containing this regulatory protein.

scholarly journals Regulation of Sporangium Formation by BldD in the Rare Actinomycete Actinoplanes missouriensis

2017 ◽  
Vol 199 (12) ◽  
Author(s):  
Yoshihiro Mouri ◽  
Kenji Konishi ◽  
Azusa Fujita ◽  
Takeaki Tezuka ◽  
Yasuo Ohnishi
Keyword(s):  
Vegetative Growth ◽  
Streptomyces Coelicolor ◽  
Morphological Differentiation ◽  
Transcriptional Regulator ◽  
Saccharopolyspora Erythraea ◽  
Transcriptional Analysis ◽  
Morphological Development ◽  
Sequencing Analysis ◽  
Content Type ◽  
Biological Studies

ABSTRACT The rare actinomycete Actinoplanes missouriensis forms sporangia, including hundreds of flagellated spores that start swimming as zoospores after their release. Under conditions suitable for vegetative growth, zoospores stop swimming and germinate. A comparative proteome analysis between zoospores and germinating cells identified 15 proteins that were produced in larger amounts in germinating cells. They include an orthologue of BldD (herein named AmBldD [BldD of A. missouriensis]), which is a transcriptional regulator involved in morphological development and secondary metabolism in Streptomyces. AmBldD was detected in mycelia during vegetative growth but was barely detected in mycelia during the sporangium-forming phase, in spite of the constant transcription of AmbldD throughout growth. An AmbldD mutant started to form sporangia much earlier than the wild-type strain, and the resulting sporangia were morphologically abnormal. Recombinant AmBldD bound a palindromic sequence, the AmBldD box, located upstream from AmbldD. 3′,5′-Cyclic di-GMP significantly enhanced the in vitro DNA-binding ability of AmBldD. A chromatin immunoprecipitation-sequencing analysis and an in silico search for AmBldD boxes revealed that AmBldD bound 346 genomic loci that contained the 19-bp inverted repeat 5′-NN(G/A)TNACN(C/G)N(G/C)NGTNA(C/T)NN-3′ as the consensus AmBldD-binding sequence. The transcriptional analysis of 27 selected AmBldD target gene candidates indicated that AmBldD should repress 12 of the 27 genes, including bldM, ssgB, whiD, ddbA, and wblA orthologues. These genes are involved in morphological development in Streptomyces coelicolor A3(2). Thus, AmBldD is a global transcriptional regulator that seems to repress the transcription of tens of genes during vegetative growth, some of which are likely to be required for sporangium formation. IMPORTANCE The rare actinomycete Actinoplanes missouriensis undergoes complex morphological differentiation, including sporangium formation. However, almost no molecular biological studies have been conducted on this bacterium. BldD is a key global regulator involved in the morphological development of streptomycetes. BldD orthologues are highly conserved among sporulating actinomycetes, but no BldD orthologues, except one in Saccharopolyspora erythraea, have been studied outside the streptomycetes. Here, it was revealed that the BldD orthologue AmBldD is essential for normal developmental processes in A. missouriensis. The AmBldD regulon seems to be different from the BldD regulon in Streptomyces coelicolor A3(2), but they share four genes that are involved in morphological differentiation in S. coelicolor A3(2).

scholarly journals Discovery of Gene Cluster for Mycosporine-Like Amino Acid Biosynthesis from Actinomycetales Microorganisms and Production of a Novel Mycosporine-Like Amino Acid by Heterologous Expression

2014 ◽  
Vol 80 (16) ◽  
pp. 5028-5036 ◽  
Author(s):  
Kiyoko T. Miyamoto ◽  
Mamoru Komatsu ◽  
Haruo Ikeda
Keyword(s):  
Amino Acid ◽  
Gene Cluster ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Dependent Manner ◽  
Biosynthetic Gene ◽  
Biosynthetic Gene Clusters ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACTMycosporines and mycosporine-like amino acids (MAAs), including shinorine (mycosporine-glycine-serine) and porphyra-334 (mycosporine-glycine-threonine), are UV-absorbing compounds produced by cyanobacteria, fungi, and marine micro- and macroalgae. These MAAs have the ability to protect these organisms from damage by environmental UV radiation. Although no reports have described the production of MAAs and the corresponding genes involved in MAA biosynthesis from Gram-positive bacteria to date, genome mining of the Gram-positive bacterial database revealed that two microorganisms belonging to the orderActinomycetales,Actinosynnema mirumDSM 43827 andPseudonocardiasp. strain P1, possess a gene cluster homologous to the biosynthetic gene clusters identified from cyanobacteria. When the two strains were grown in liquid culture,Pseudonocardiasp. accumulated a very small amount of MAA-like compound in a medium-dependent manner, whereasA. mirumdid not produce MAAs under any culture conditions, indicating that the biosynthetic gene cluster ofA. mirumwas in a cryptic state in this microorganism. In order to characterize these biosynthetic gene clusters, each biosynthetic gene cluster was heterologously expressed in an engineered host,Streptomyces avermitilisSUKA22. Since the resultant transformants carrying the entire biosynthetic gene cluster controlled by an alternative promoter produced mainly shinorine, this is the first confirmation of a biosynthetic gene cluster for MAA from Gram-positive bacteria. Furthermore,S. avermitilisSUKA22 transformants carrying the biosynthetic gene cluster for MAA ofA. mirumaccumulated not only shinorine and porphyra-334 but also a novel MAA. Structure elucidation revealed that the novel MAA is mycosporine-glycine-alanine, which substitutesl-alanine for thel-serine of shinorine.

scholarly journals Alternative Biosynthetic Starter Units Enhance the Structural Diversity of Cyanobacterial Lipopeptides

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Jan Mareš ◽  
Jan Hájek ◽  
Petra Urajová ◽  
Andreja Kust ◽  
Jouni Jokela ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Gene Cluster ◽  
Plasma Membranes ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Published Data ◽  
Biosynthetic Gene ◽  
Structural Variants ◽  
Biosynthetic Gene Clusters ◽  
Content Type

ABSTRACT Puwainaphycins (PUWs) and minutissamides (MINs) are structurally analogous cyclic lipopeptides possessing cytotoxic activity. Both types of compound exhibit high structural variability, particularly in the fatty acid (FA) moiety. Although a biosynthetic gene cluster responsible for synthesis of several PUW variants has been proposed in a cyanobacterial strain, the genetic background for MINs remains unexplored. Herein, we report PUW/MIN biosynthetic gene clusters and structural variants from six cyanobacterial strains. Comparison of biosynthetic gene clusters indicates a common origin of the PUW/MIN hybrid nonribosomal peptide synthetase and polyketide synthase. Surprisingly, the biosynthetic gene clusters encode two alternative biosynthetic starter modules, and analysis of structural variants suggests that initiation by each of the starter modules results in lipopeptides of differing lengths and FA substitutions. Among additional modifications of the FA chain, chlorination of minutissamide D was explained by the presence of a putative halogenase gene in the PUW/MIN gene cluster of Anabaena minutissima strain UTEX B 1613. We detected PUW variants bearing an acetyl substitution in Symplocastrum muelleri strain NIVA-CYA 644, consistent with an O-acetyltransferase gene in its biosynthetic gene cluster. The major lipopeptide variants did not exhibit any significant antibacterial activity, and only the PUW F variant was moderately active against yeast, consistent with previously published data suggesting that PUWs/MINs interact preferentially with eukaryotic plasma membranes. IMPORTANCE Herein, we deciphered the most important biosynthetic traits of a prominent group of bioactive lipopeptides. We reveal evidence for initiation of biosynthesis by two alternative starter units hardwired directly in the same gene cluster, eventually resulting in the production of a remarkable range of lipopeptide variants. We identified several unusual tailoring genes potentially involved in modifying the fatty acid chain. Careful characterization of these biosynthetic gene clusters and their diverse products could provide important insight into lipopeptide biosynthesis in prokaryotes. Some of the variants identified exhibit cytotoxic and antifungal properties, and some are associated with a toxigenic biofilm-forming strain. The findings may prove valuable to researchers in the fields of natural product discovery and toxicology.

scholarly journals Analysis of the Tunicamycin Biosynthetic Gene Cluster ofStreptomyces chartreusisReveals New Insights into Tunicamycin Production and Immunity

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
David Widdick ◽  
Sylvain F. Royer ◽  
Hua Wang ◽  
Natalia M. Vior ◽  
Juan Pablo Gomez-Escribano ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Streptomyces Coelicolor ◽  
Biosynthetic Gene Cluster ◽  
Transcriptional Analysis ◽  
Efficient Production ◽  
Primary Metabolism ◽  
Biosynthetic Gene ◽  
Content Type ◽  
High Degree ◽  
Single Operon

ABSTRACTThe tunicamycin biosynthetic gene cluster ofStreptomyces chartreusisconsists of 14 genes (tunAtotunN) with a high degree of apparent translational coupling. Transcriptional analysis revealed that all of these genes are likely to be transcribed as a single operon from two promoters,tunp1 andtunp2. In-frame deletion analysis revealed that just six of these genes (tunABCDEH) are essential for tunicamycin production in the heterologous hostStreptomyces coelicolor, while five (tunFGKLN) with likely counterparts in primary metabolism are not necessary, but presumably ensure efficient production of the antibiotic at the onset of tunicamycin biosynthesis. Three genes are implicated in immunity, namely,tunIandtunJ, which encode a two-component ABC transporter presumably required for export of the antibiotic, andtunM, which encodes a putativeS-adenosylmethionine (SAM)-dependent methyltransferase. Expression oftunIJortunMinS. coelicolorconferred resistance to exogenous tunicamycin. The results presented here provide new insights into tunicamycin biosynthesis and immunity.

scholarly journals Discovery and Biosynthesis of the Antibiotic Bicyclomycin in Distantly Related Bacterial Classes

2018 ◽  
Vol 84 (9) ◽  
Author(s):  
Natalia M. Vior ◽  
Rodney Lacret ◽  
Govind Chandra ◽  
Siobhán Dorai-Raj ◽  
Martin Trick ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Gene Cluster ◽  
Gene Clusters ◽  
Opportunistic Pathogen ◽  
Biosynthetic Gene Cluster ◽  
Wide Distribution ◽  
Biosynthetic Gene ◽  
P450 Monooxygenase ◽  
Content Type ◽  
Transcription Termination Factor

ABSTRACTBicyclomycin (BCM) is a clinically promising antibiotic that is biosynthesized byStreptomyces cinnamoneusDSM 41675. BCM is structurally characterized by a core cyclo(l-Ile-l-Leu) 2,5-diketopiperazine (DKP) that is extensively oxidized. Here, we identify the BCM biosynthetic gene cluster, which shows that the core of BCM is biosynthesized by a cyclodipeptide synthase, and the oxidative modifications are introduced by five 2-oxoglutarate-dependent dioxygenases and one cytochrome P450 monooxygenase. The discovery of the gene cluster enabled the identification of BCM pathways encoded by the genomes of hundreds ofPseudomonas aeruginosaisolates distributed globally, and heterologous expression of the pathway fromP. aeruginosaSCV20265 demonstrated that the product is chemically identical to BCM produced byS. cinnamoneus. Overall, putative BCM gene clusters have been found in at least seven genera spanningActinobacteriaandProteobacteria(Alphaproteobacteria,Betaproteobacteria, andGammaproteobacteria). This represents a rare example of horizontal gene transfer of an intact biosynthetic gene cluster across such distantly related bacteria, and we show that these gene clusters are almost always associated with mobile genetic elements.IMPORTANCEBicyclomycin is the only natural product antibiotic that selectively inhibits the transcription termination factor Rho. This mechanism of action, combined with its proven biological safety and its activity against clinically relevant Gram-negative bacterial pathogens, makes it a very promising antibiotic candidate. Here, we report the identification of the bicyclomycin biosynthetic gene cluster in the known bicyclomycin-producing organismStreptomyces cinnamoneus, which will enable the engineered production of new bicyclomycin derivatives. The identification of this gene cluster also led to the discovery of hundreds of bicyclomycin pathways encoded in highly diverse bacteria, including in the opportunistic pathogenPseudomonas aeruginosa. This wide distribution of a complex biosynthetic pathway is very unusual and provides an insight into how a pathway for an antibiotic can be transferred between diverse bacteria.

scholarly journals A Hierarchical Network of Four Regulatory Genes Controlling Production of the Polyene Antibiotic Candicidin in Streptomyces sp. Strain FR-008

2020 ◽  
Vol 86 (9) ◽  
Author(s):  
Yanping Zhu ◽  
Wenhao Xu ◽  
Jing Zhang ◽  
Peipei Zhang ◽  
Zhilong Zhao ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Regulatory Network ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Regulatory Genes ◽  
Transcriptional Analysis ◽  
Antibiotic Biosynthesis ◽  
Biosynthetic Gene ◽  
Polyene Antibiotic ◽  
Biosynthetic Gene Clusters

ABSTRACT The four regulatory genes fscR1 to fscR4 in Streptomyces sp. strain FR-008 form a genetic arrangement that is widely distributed in macrolide-producing bacteria. Our previous work has demonstrated that fscR1 and fscR4 are critical for production of the polyene antibiotic candicidin. In this study, we further characterized the roles of the other two regulatory genes, fscR2 and fscR3, focusing on the relationship between these four regulatory genes. Disruption of a single or multiple regulatory genes did not affect bacterial growth, but transcription of genes in the candicidin biosynthetic gene cluster decreased, and candicidin production was abolished, indicating a critical role for each of the four regulatory genes, including fscR2 and fscR3, in candicidin biosynthesis. We found that fscR1 to fscR4, although differentially expressed throughout the growth phase, displayed similar temporal expression patterns, with an abrupt increase in the early exponential phase, coincident with initial detection of antibiotic production in the same phase. Our data suggest that the four regulatory genes fscR1 to fscR4 have various degrees of control over structural genes in the biosynthetic cluster under the conditions examined. Extensive transcriptional analysis indicated that complex regulation exists between these four regulatory genes, forming a regulatory network, with fscR1 and fscR4 functioning at a lower level. Comprehensive cross-complementation analysis indicates that functional complementation is restricted among the four regulators and unidirectional, with fscR1 complementing the loss of fscR3 or -4 and fscR4 complementing loss of fscR2. Our study provides more insights into the roles of, and the regulatory network formed by, these four regulatory genes controlling production of an important pharmaceutical compound. IMPORTANCE The regulation of antibiotic biosynthesis by Streptomyces species is complex, especially for biosynthetic gene clusters with multiple regulatory genes. The biosynthetic gene cluster for the polyene antibiotic candicidin contains four consecutive regulatory genes, which encode regulatory proteins from different families and which form a subcluster within the larger biosynthetic gene cluster in Streptomyces sp. FR-008. Syntenic arrangements of these regulatory genes are widely distributed in polyene gene clusters, such as the amphotericin and nystatin gene clusters, suggesting a conserved regulatory mechanism controlling production of these clinically important medicines. However, the relationships between these multiple regulatory genes are unknown. In this study, we determined that each of these four regulatory genes is critical for candicidin production. Additionally, using transcriptional analyses, bioassays, high-performance liquid chromatography (HPLC) analysis, and genetic cross-complementation, we showed that FscR1 to FscR4 comprise a hierarchical regulatory network that controls candicidin production and is likely representative of how expression of other polyene biosynthetic gene clusters is controlled.

scholarly journals The Bacillus cereus Group Is an Excellent Reservoir of Novel Lanthipeptides

2014 ◽  
Vol 81 (5) ◽  
pp. 1765-1774 ◽  
Author(s):  
Bingyue Xin ◽  
Jinshui Zheng ◽  
Ziya Xu ◽  
Xiaoling Song ◽  
Lifang Ruan ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Gene Cluster ◽  
Transmembrane Protein ◽  
Gene Clusters ◽  
Transcriptional Analysis ◽  
Exponential Growth Phase ◽  
Type I ◽  
Structural Genes ◽  
Gram Positive ◽  
Content Type

ABSTRACTLantibiotics are ribosomally synthesized peptides that contain multiple posttranslational modifications. Research on lantibiotics has increased recently, mainly due to their broad-spectrum antimicrobial activity, especially against some clinical Gram-positive pathogens. Many reports about various bacteriocins in theBacillus cereusgroup have been published, but few were about lantibiotics. In this study, we identified 101 putative lanthipeptide gene clusters from 77 out of 223 strains of this group, and these gene clusters were further classified into 20 types according to their gene organization and the homologies of their functional genes. Among them, 18 types were novel and have not yet been experimentally verified. Two novel lantibiotics (thuricin 4A-4 and its derivative, thuricin 4A-4D) were identified in the type I-1 lanthipeptide gene cluster and showed activity against all tested Gram-positive bacteria. The mode of action of thuricin 4A-4 was studied, and we found that it acted as a bactericidal compound. The transcriptional analysis of four structural genes (thiA1,thiA2,thiA3, andthiA4) in the thuricin 4A gene cluster showed that only one structural gene,thiA4, showed efficient transcription in the exponential growth phase; the other three structural genes did not. In addition, the putative transmembrane protein ThiI was responsible for thuricin 4A-4 immunity. Genome analysis and functional verification illustrated thatB. cereusgroup strains were a prolific source of novel lantibiotics.

scholarly journals High Level of Spinosad Production in the Heterologous Host Saccharopolyspora erythraea

2016 ◽  
Vol 82 (18) ◽  
pp. 5603-5611 ◽  
Author(s):  
Jun Huang ◽  
Zhen Yu ◽  
Mei-Hong Li ◽  
Ji-Dong Wang ◽  
Hua Bai ◽  
...  
Keyword(s):  
Heterologous Expression ◽  
Gene Cluster ◽  
Gene Clusters ◽  
Industrial Applications ◽  
Global Market ◽  
Saccharopolyspora Erythraea ◽  
Market Demand ◽  
Saccharopolyspora Spinosa ◽  
Biosynthesis Gene Cluster ◽  
Content Type

ABSTRACTSpinosad, a highly effective insecticide, has an excellent environmental and mammalian toxicological profile. Global market demand for spinosad is huge and growing. However, after much effort, there has been almost no improvement in the spinosad yield from the original producer,Saccharopolyspora spinosa. Here, we report the heterologous expression of spinosad usingSaccharopolyspora erythraeaas a host. The native erythromycin polyketide synthase (PKS) genes inS. erythraeawere replaced by the assembled spinosad gene cluster through iterative recombination. The production of spinosad could be detected in the recombinant strains containing the whole biosynthesis gene cluster. Both metabolic engineering and UV mutagenesis were applied to further improve the yield of spinosad. The final strain, AT-ES04PS-3007, which could produce spinosad with a titer of 830 mg/liter, has significant potential in industrial applications.IMPORTANCEThis work provides an innovative and promising way to improve the industrial production of spinosad. At the same time, it also describes a successful method of heterologous expression for target metabolites of interest by replacing large gene clusters.

scholarly journals New Insights into Chloramphenicol Biosynthesis in Streptomyces venezuelae ATCC 10712

2014 ◽  
Vol 58 (12) ◽  
pp. 7441-7450 ◽  
Author(s):  
Lorena T. Fernández-Martínez ◽  
Chiara Borsetto ◽  
Juan Pablo Gomez-Escribano ◽  
Maureen J. Bibb ◽  
Mahmoud M. Al-Bassam ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Acyl Carrier Protein ◽  
Bioinformatic Analysis ◽  
Biosynthetic Gene Cluster ◽  
Transcriptional Analysis ◽  
Biosynthetic Gene ◽  
Phosphopantetheinyl Transferase ◽  
Streptomyces Venezuelae ◽  
Content Type ◽  
New Genes

ABSTRACTComparative genome analysis revealed seven uncharacterized genes,sven0909tosven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (sven0916–sven0928) ofStreptomyces venezuelaestrain ATCC 10712 that was absent in a closely relatedStreptomycesstrain that does not produce chloramphenicol. Transcriptional analysis suggested that three of these genes might be involved in chloramphenicol production, a prediction confirmed by the construction of deletion mutants. These three genes encode a cluster-associated transcriptional activator (Sven0913), a phosphopantetheinyl transferase (Sven0914), and a Na+/H+antiporter (Sven0915). Bioinformatic analysis also revealed the presence of a previously undetected gene,sven0925, embedded within the chloramphenicol biosynthetic gene cluster that appears to encode an acyl carrier protein, bringing the number of new genes likely to be involved in chloramphenicol production to four. Microarray experiments and synteny comparisons also suggest thatsven0929is part of the biosynthetic gene cluster. This has allowed us to propose an updated and revised version of the chloramphenicol biosynthetic pathway.

scholarly journals Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

2012 ◽  
Vol 78 (12) ◽  
pp. 4412-4419 ◽  
Author(s):  
Tim Kamber ◽  
Theresa A. Lansdell ◽  
Virginia O. Stockwell ◽  
Carol A. Ishimaru ◽  
Theo H. M. Smits ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Orthologous Gene ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Sequence Comparisons ◽  
Content Type ◽  
Serratia Proteamaculans ◽  
Biocontrol Strain ◽  
Pantoea Vagans

ABSTRACTPantoea vagansC9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth ofErwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates ofP. vagansC9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known asNß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster inP. vagansC9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters inPantoea agglomeransCU0119 andSerratia proteamaculans568. A low incidence of detection of the biosynthetic cluster in a collection of 45Pantoeaspp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains.

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