Novel Gene Clusters and Metabolic Pathway Involved in 3,5,6-Trichloro-2-Pyridinol Degradation by Ralstonia sp. Strain T6

ABSTRACT3,5,6-Trichloro-2-pyridinol (TCP) is a widespread pollutant. Some bacteria and fungi have been reported to degrade TCP, but the gene clusters responsible for TCP biodegradation have not been characterized. In this study, a fragment of the reduced flavin adenine dinucleotide (FADH2)-dependent monooxygenase genetcpAwas amplified from the genomic DNA ofRalstoniasp. strain T6 with degenerate primers. ThetcpAdisruption mutant strain T6-ΔtcpAcould not degrade TCP but could degrade the green intermediate metabolite 3,6-dihydroxypyridine-2,5-dione (DHPD), which was generated during TCP biodegradation by strain T6. The flanking sequences oftcpAwere obtained by self-formed adaptor PCR.tcpRXAgenes constitute a gene cluster. TcpR and TcpX are closely related to the LysR family transcriptional regulator and flavin reductase, respectively. T6-ΔtcpA-com, the complementation strain for the mutant strain T6-ΔtcpA, recovered the ability to degrade TCP, and the strainEscherichia coliDH10B-tcpRXA, which expressed thetcpRXAgene cluster, had the ability to transform TCP to DHPD, indicating thattcpAis a key gene in the initial step of TCP degradation and that TcpA dechlorinates TCP to DHPD. A library of DHPD degradation-deficient mutants of strain T6 was obtained by random transposon mutagenesis. The fragments flanking the Mariner transposon were amplified and sequenced, and thedhpRIJKgene cluster was cloned. DhpJ could transform DHPD to yield an intermediate product, 5-amino-2,4,5-trioxopentanoicacid (ATOPA), which was further degraded by DhpI. DhpR and DhpK are closely related to the AraC family transcriptional regulator and the MFS family transporter, respectively.

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

Journal of Bacteriology ◽

10.1128/jb.00447-17 ◽

2017 ◽

Vol 200 (2) ◽

Cited By ~ 16

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.

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Regulation of the Alkane Hydroxylase CYP153 Gene in a Gram-Positive Alkane-Degrading Bacterium, Dietzia sp. Strain DQ12-45-1b

Applied and Environmental Microbiology ◽

10.1128/aem.02811-15 ◽

2015 ◽

Vol 82 (2) ◽

pp. 608-619 ◽

Cited By ~ 19

Author(s):

Jie-Liang Liang ◽

Jing-Hong JiangYang ◽

Yong Nie ◽

Xiao-Lei Wu

Keyword(s):

Gene Cluster ◽

Mutant Strain ◽

Gene Transcription ◽

Gene Promoter ◽

Gene Clusters ◽

Gram Positive ◽

Content Type ◽

Degrading Bacterium ◽

Degrading Bacteria ◽

Arac Family

ABSTRACTCYP153, one of the most common medium-chainn-alkane hydroxylases belonging to the cytochrome P450 superfamily, is widely expressed inn-alkane-degrading bacteria. CYP153 is also thought to cooperate with AlkB in degrading variousn-alkanes. However, the mechanisms regulating the expression of the protein remain largely unknown. In this paper, we studied CYP153 gene transcription regulation by the potential AraC family regulator (CypR) located upstream of the CYP153 gene cluster in a broad-spectrumn-alkane-degrading Gram-positive bacterium,Dietziasp. strain DQ12-45-1b. We first identified the transcriptional start site and the promoter of the CYP153 gene cluster. Sequence alignment of upstream regions of CYP153 gene clusters revealed high conservation in the −10 and −35 regions inActinobacteria. Further analysis of the β-galactosidase activity in the CYP153 gene promoter-lacZfusion cell indicated that the CYP153 gene promoter was induced byn-alkanes comprised of 8 to 14 carbon atoms, but not by derived decanol and decanic acid. Moreover, we constructed acypRmutant strain and found that the CYP153 gene promoter activities and CYP153 gene transcriptional levels in the mutant strain were depressed compared with those in the wild-type strain in the presence ofn-alkanes, suggesting that CypR served as an activator for the CYP153 gene promoter. By comparing CYP153 gene arrangements inActinobacteriaandProteobacteria, we found that the AraC family regulator is ubiquitously located upstream of the CYP153 gene, suggesting its universal regulatory role in CYP153 gene transcription. We further hypothesize that the observed mode of CYP153 gene regulation is shared by manyActinobacteria.

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A Novel CO-Responsive Transcriptional Regulator and Enhanced H2Production by an Engineered Thermococcus onnurineus NA1 Strain

Applied and Environmental Microbiology ◽

10.1128/aem.03019-14 ◽

2014 ◽

Vol 81 (5) ◽

pp. 1708-1714 ◽

Cited By ~ 25

Author(s):

Min-Sik Kim ◽

Ae Ran Choi ◽

Seong Hyuk Lee ◽

Hae-Chang Jung ◽

Seung Seob Bae ◽

...

Keyword(s):

Production Rate ◽

Gene Cluster ◽

Type Strain ◽

Wild Type Strain ◽

Regulatory System ◽

Transcriptional Regulator ◽

Bioreactor Culture ◽

Wild Type ◽

Content Type ◽

Transcriptional Regulatory

ABSTRACTGenome analysis revealed the existence of a putative transcriptional regulatory system governing CO metabolism inThermococcus onnurineusNA1, a carboxydotrophic hydrogenogenic archaeon. The regulatory system is composed of CorQ with a 4-vinyl reductase domain and CorR with a DNA-binding domain of the LysR-type transcriptional regulator family in close proximity to the CO dehydrogenase (CODH) gene cluster. Homologous genes of the CorQR pair were also found in the genomes ofThermococcusspecies and “CandidatusKorarchaeum cryptofilum” OPF8. In-frame deletion of eithercorQorcorRcaused a severe impairment in CO-dependent growth and H2production. WhencorQandcorRdeletion mutants were complemented by introducing thecorQRgenes under the control of a strong promoter, the mRNA and protein levels of the CODH gene were significantly increased in a ΔCorR strain complemented with integratedcorQR(ΔCorR/corQR↑) compared with those in the wild-type strain. In addition, the ΔCorR/corQR↑strain exhibited a much higher H2production rate (5.8-fold) than the wild-type strain in a bioreactor culture. The H2production rate (191.9 mmol liter−1h−1) and the specific H2production rate (249.6 mmol g−1h−1) of this strain were extremely high compared with those of CO-dependent H2-producing prokaryotes reported so far. These results suggest that thecorQRgenes encode a positive regulatory protein pair for the expression of a CODH gene cluster. The study also illustrates that manipulation of the transcriptional regulatory system can improve biological H2production.

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Overproduction of Ristomycin A by Activation of a Silent Gene Cluster in Amycolatopsis japonicum MG417-CF17

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03512-14 ◽

2014 ◽

Vol 58 (10) ◽

pp. 6185-6196 ◽

Cited By ~ 51

Author(s):

Marius Spohn ◽

Norbert Kirchner ◽

Andreas Kulik ◽

Angelika Jochim ◽

Felix Wolf ◽

...

Keyword(s):

Mass Spectrometry ◽

Gene Cluster ◽

High Performance ◽

Pathogenic Bacteria ◽

Genome Mining ◽

Gene Clusters ◽

Von Willebrand Disease ◽

Biosynthesis Gene Cluster ◽

Content Type ◽

Bioinformatic Tools

ABSTRACTThe emergence of antibiotic-resistant pathogenic bacteria within the last decades is one reason for the urgent need for new antibacterial agents. A strategy to discover new anti-infective compounds is the evaluation of the genetic capacity of secondary metabolite producers and the activation of cryptic gene clusters (genome mining). One genus known for its potential to synthesize medically important products isAmycolatopsis. However,Amycolatopsis japonicumdoes not produce an antibiotic under standard laboratory conditions. In contrast to mostAmycolatopsisstrains,A. japonicumis genetically tractable with different methods. In order to activate a possible silent glycopeptide cluster, we introduced a gene encoding the transcriptional activator of balhimycin biosynthesis, thebbrgene fromAmycolatopsis balhimycina(bbrAba), intoA. japonicum. This resulted in the production of an antibiotically active compound. Following whole-genome sequencing ofA. japonicum, 29 cryptic gene clusters were identified by genome mining. One of these gene clusters is a putative glycopeptide biosynthesis gene cluster. Using bioinformatic tools, ristomycin (syn. ristocetin), a type III glycopeptide, which has antibacterial activity and which is used for the diagnosis of von Willebrand disease and Bernard-Soulier syndrome, was deduced as a possible product of the gene cluster. Chemical analyses by high-performance liquid chromatography and mass spectrometry (HPLC-MS), tandem mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR) spectroscopy confirmed thein silicoprediction that the recombinantA. japonicum/pRM4-bbrAbasynthesizes ristomycin A.

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A Bacterial Microcompartment Is Used for Choline Fermentation byEscherichia coli536

Journal of Bacteriology ◽

10.1128/jb.00764-17 ◽

2018 ◽

Vol 200 (10) ◽

Cited By ~ 12

Author(s):

Taylor I. Herring ◽

Tiffany N. Harris ◽

Chiranjit Chowdhury ◽

Sujit Kumar Mohanty ◽

Thomas A. Bobik

Keyword(s):

Electron Microscopy ◽

Heart Disease ◽

Gene Cluster ◽

Transcriptional Regulator ◽

Human Gut ◽

Content Type ◽

E Coli ◽

Bacterial Microcompartment ◽

New Type ◽

Insight Into

ABSTRACTBacterial choline degradation in the human gut has been associated with cancer and heart disease. In addition, recent studies found that a bacterial microcompartment is involved in choline utilization byProteusandDesulfovibriospecies. However, many aspects of this process have not been fully defined. Here, we investigate choline degradation by the uropathogenEscherichia coli536. Growth studies indicatedE. coli536 degrades choline primarily by fermentation. Electron microscopy indicated that a bacterial microcompartment was used for this process. Bioinformatic analyses suggested that the choline utilization (cut) gene cluster ofE. coli536 includes two operons, one containing three genes and a main operon of 13 genes. Regulatory studies indicate that thecutXgene encodes a positive transcriptional regulator required for induction of the maincutoperon in response to choline supplementation. Each of the 16 genes in thecutcluster was individually deleted, and phenotypes were examined. ThecutX,cutY,cutF,cutO,cutC,cutD,cutU, andcutVgenes were required for choline degradation, but the remaining genes of thecutcluster were not essential under the conditions used. The reasons for these varied phenotypes are discussed.IMPORTANCEHere, we investigate choline degradation inE. coli536. These studies provide a basis for understanding a new type of bacterial microcompartment and may provide deeper insight into the link between choline degradation in the human gut and cancer and heart disease. These are also the first studies of choline degradation inE. coli536, an organism for which sophisticated genetic analysis methods are available. In addition, thecutgene cluster ofE. coli536 is located in pathogenicity island II (PAI-II536) and hence might contribute to pathogenesis.

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Plasmid-Borne Type E Neurotoxin Gene Clusters in Clostridium botulinum Strains

Applied and Environmental Microbiology ◽

10.1128/aem.00080-13 ◽

2013 ◽

Vol 79 (12) ◽

pp. 3856-3859 ◽

Cited By ~ 17

Author(s):

Zhen Zhang ◽

Hannamari Hintsa ◽

Ying Chen ◽

Hannu Korkeala ◽

Miia Lindström

Keyword(s):

Gene Cluster ◽

Gel Electrophoresis ◽

Clostridium Botulinum ◽

Southern Hybridization ◽

Gene Clusters ◽

Pulsed Field Gel Electrophoresis ◽

Content Type ◽

Pulsed Field ◽

Large Plasmids

ABSTRACTA collection of 36Clostridium botulinumtype E strains was examined by pulsed-field gel electrophoresis (PFGE) and Southern hybridization with probes targeted tobotEandorfX1in the neurotoxin gene cluster. Three strains were found to contain neurotoxin subtype E1 gene clusters in large plasmids of about 146 kb in size.

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Fur-Dam Regulatory Interplay at an Internal Promoter of the Enteroaggregative Escherichia coli Type VI Secretion sci1 Gene Cluster

Journal of Bacteriology ◽

10.1128/jb.00075-20 ◽

2020 ◽

Vol 202 (10) ◽

Cited By ~ 3

Author(s):

Yannick R. Brunet ◽

Christophe S. Bernard ◽

Eric Cascales

Keyword(s):

Escherichia Coli ◽

Gene Cluster ◽

Gene Clusters ◽

Secretion System ◽

Target Cells ◽

Type Vi Secretion System ◽

Content Type ◽

Internal Promoter ◽

E Coli ◽

Type Vi Secretion

ABSTRACT The type VI secretion system (T6SS) is a weapon for delivering effectors into target cells that is widespread in Gram-negative bacteria. The T6SS is a highly versatile machine, as it can target both eukaryotic and prokaryotic cells, and it has been proposed that T6SSs are adapted to the specific needs of each bacterium. The expression of T6SS gene clusters and the activation of the secretion apparatus are therefore tightly controlled. In enteroaggregative Escherichia coli (EAEC), the sci1 T6SS gene cluster is subject to a complex regulation involving both the ferric uptake regulator (Fur) and DNA adenine methylase (Dam)-dependent DNA methylation. In this study, an additional, internal, promoter was identified within the sci1 gene cluster using +1 transcriptional mapping. Further analyses demonstrated that this internal promoter is controlled by a mechanism strictly identical to that of the main promoter. The Fur binding box overlaps the −10 transcriptional element and a Dam methylation site, GATC-32. Hence, the expression of the distal sci1 genes is repressed and the GATC-32 site is protected from methylation in iron-rich conditions. The Fur-dependent protection of GATC-32 was confirmed by an in vitro methylation assay. In addition, the methylation of GATC-32 negatively impacted Fur binding. The expression of the sci1 internal promoter is therefore controlled by iron availability through Fur regulation, whereas Dam-dependent methylation maintains a stable ON expression in iron-limited conditions. IMPORTANCE Bacteria use weapons to deliver effectors into target cells. One of these weapons, the type VI secretion system (T6SS), assembles a contractile tail acting as a spring to propel a toxin-loaded needle. Its expression and activation therefore need to be tightly regulated. Here, we identified an internal promoter within the sci1 T6SS gene cluster in enteroaggregative E. coli. We show that this internal promoter is controlled by Fur and Dam-dependent methylation. We further demonstrate that Fur and Dam compete at the −10 transcriptional element to finely tune the expression of T6SS genes. We propose that this elegant regulatory mechanism allows the optimum production of the T6SS in conditions where enteroaggregative E. coli encounters competing species.

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The Gene Cluster forpara-Nitrophenol Catabolism Is Responsible for 2-Chloro-4-Nitrophenol Degradation in Burkholderia sp. Strain SJ98

Applied and Environmental Microbiology ◽

10.1128/aem.02093-14 ◽

2014 ◽

Vol 80 (19) ◽

pp. 6212-6222 ◽

Cited By ~ 31

Author(s):

Jun Min ◽

Jun-Jie Zhang ◽

Ning-Yi Zhou

Keyword(s):

Gene Cluster ◽

Gene Knockout ◽

Gene Clusters ◽

Sole Source ◽

Pcr Analysis ◽

Content Type ◽

Reverse Transcription Pcr ◽

Biochemical Analyses ◽

Nitrophenol Degradation

ABSTRACTBurkholderiasp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) orpara-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of thepnpgenes in thepnpABA1CDEFcluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activityin vitroin the conversion of 2C4NP to CBQ. Genetic analyses indicated thatpnpAplays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.

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A Novel AdpA Homologue Negatively Regulates Morphological Differentiation inStreptomyces xiamenensis318

Applied and Environmental Microbiology ◽

10.1128/aem.03107-18 ◽

2019 ◽

Vol 85 (7) ◽

Cited By ~ 4

Author(s):

Xu-Liang Bu ◽

Jing-Yi Weng ◽

Bei-Bei He ◽

Min-Juan Xu ◽

Jun Xu

Keyword(s):

Cell Growth ◽

Secondary Metabolism ◽

Gene Cluster ◽

Morphological Differentiation ◽

Gene Clusters ◽

Transcriptional Level ◽

Negative Effects ◽

Promoter Regions ◽

Content Type ◽

Enhanced Production

ABSTRACTThe pleiotropic transcriptional regulator AdpA positively controls morphological differentiation and regulates secondary metabolism in mostStreptomycesspecies.Streptomyces xiamenensis318 has a linear chromosome 5.96 Mb in size. How AdpA affects secondary metabolism and morphological differentiation in such a naturally minimized genomic background is unknown. Here, we demonstrated that AdpASx, an AdpA orthologue inS. xiamenensis, negatively regulates cell growth and sporulation and bidirectionally regulates the biosynthesis of xiamenmycin and polycyclic tetramate macrolactams (PTMs) inS. xiamenensis318. Overexpression of theadpASxgene inS. xiamenensis318 had negative effects on morphological differentiation and resulted in reduced transcription of putativessgA,ftsZ,ftsH,amfC,whiB,wblA1,wblA2,wblE, and a gene encoding sporulation-associated protein (sxim_29740), whereas the transcription of putativebldDandbldAgenes was upregulated. Overexpression ofadpASxled to significantly enhanced production of xiamenmycin but had detrimental effects on the production of PTMs. As expected, the transcriptional level of theximgene cluster was upregulated, whereas the PTM gene cluster was downregulated. Moreover, AdpASxnegatively regulated the transcription of its own gene. Electrophoretic mobility shift assays revealed that AdpASxcan bind the promoter regions of structural genes of both theximand PTM gene clusters as well as to the promoter regions of genes potentially involved in the cell growth and differentiation ofS. xiamenensis318. We report that an AdpA homologue has negative effects on morphological differentiation inS. xiamenensis318, a finding confirmed when AdpASxwas introduced into the heterologous hostStreptomyces lividansTK24.IMPORTANCEAdpA is a key regulator of secondary metabolism and morphological differentiation inStreptomycesspecies. However, AdpA had not been reported to negatively regulate morphological differentiation. Here, we characterized the regulatory role of AdpASxinStreptomyces xiamenensis318, which has a naturally streamlined genome. In this strain, AdpASxnegatively regulated cell growth and morphological differentiation by directly controlling genes associated with these functions. AdpASxalso bidirectionally controlled the biosynthesis of xiamenmycin and PTMs by directly regulating their gene clusters rather than through other regulators. Our findings provide additional evidence for the versatility of AdpA in regulating morphological differentiation and secondary metabolism inStreptomyces.

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Two Master Switch Regulators Trigger A40926 Biosynthesis in Nonomuraea sp. Strain ATCC 39727

Journal of Bacteriology ◽

10.1128/jb.00262-15 ◽

2015 ◽

Vol 197 (15) ◽

pp. 2536-2544 ◽

Cited By ~ 24

Author(s):

Letizia Lo Grasso ◽

Sonia Maffioli ◽

Margherita Sosio ◽

Mervyn Bibb ◽

Anna Maria Puglia ◽

...

Keyword(s):

Gene Cluster ◽

Antibiotic Production ◽

Regulatory Protein ◽

Gene Clusters ◽

Biosynthetic Gene Cluster ◽

Regulatory Mechanisms ◽

Antibiotic Biosynthesis ◽

Strain Atcc ◽

Protein Coding ◽

Content Type

ABSTRACTThe actinomyceteNonomuraeasp. strain ATCC 39727 produces the glycopeptide A40926, the precursor of dalbavancin. Biosynthesis of A40926 is encoded by thedbvgene cluster, which contains 37 protein-coding sequences that participate in antibiotic biosynthesis, regulation, immunity, and export. In addition to the positive regulatory protein Dbv4, the A40926-biosynthetic gene cluster encodes two additional putative regulators, Dbv3 and Dbv6. Independent mutations in these genes, combined with bioassays and liquid chromatography-mass spectrometry (LC-MS) analyses, demonstrated that Dbv3 and Dbv4 are both required for antibiotic production, while inactivation ofdbv6had no effect. In addition, overexpression ofdbv3led to higher levels of A40926 production. Transcriptional and quantitative reverse transcription (RT)-PCR analyses showed that Dbv4 is essential for the transcription of two operons,dbv14-dbv8anddbv30-dbv35, while Dbv3 positively controls the expression of four monocistronic transcription units (dbv4,dbv29,dbv36, anddbv37) and of six operons (dbv2-dbv1,dbv14-dbv8,dbv17-dbv15,dbv21-dbv20,dbv24-dbv28, anddbv30-dbv35). We propose a complex and coordinated model of regulation in which Dbv3 directly or indirectly activates transcription ofdbv4and controls biosynthesis of 4-hydroxyphenylglycine and the heptapeptide backbone, A40926 export, and some tailoring reactions (mannosylation and hexose oxidation), while Dbv4 directly regulates biosynthesis of 3,5-dihydroxyphenylglycine and other tailoring reactions, including the four cross-links, halogenation, glycosylation, and acylation.IMPORTANCEThis report expands knowledge of the regulatory mechanisms used to control the biosynthesis of the glycopeptide antibiotic A40926 in the actinomyceteNonomuraeasp. strain ATCC 39727. A40926 is the precursor of dalbavancin, approved for treatment of skin infections by Gram-positive bacteria. Therefore, understanding the regulation of its biosynthesis is also of industrial importance. So far, the regulatory mechanisms used to control two other similar glycopeptides (balhimycin and teicoplanin) have been elucidated, and beyond a common step, different clusters seem to have devised different strategies to control glycopeptide production. Thus, our work provides one more example of the pitfalls of deducing regulatory roles from bioinformatic analyses only, even when analyzing gene clusters directing the synthesis of structurally related compounds.

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