<i>Photorhabdus</i>‐nematode symbiosis is dependent on <i>hfq</i>‐mediated regulation of secondary metabolites

Tobias, Nicholas J.; Heinrich, Antje K.; Eresmann, Helena; Wright, Patrick R.; Neubacher, Nick; Backofen, Rolf; Bode, Helge B.

doi:10.1111/1462-2920.13502

Cited by 63 publications

(79 citation statements)

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“…Recently it became clear that global regulators or QS signals can alter the production of NPs in Photorhabdus/Xenorhabdus (Brameyer et al, 2014). Hfq was identified as a regulator of various NPs in P. luminescens (Tobias et al, 2017), as well as LeuO, HexA and Lrp in P. luminescens , X. nematophila and X. szentirmaii (Engel et al, 2017). In order to investigate if LuxS plays a similar role in NP regulation in these three strains, the respective luxS deletion strains were constructed and analyzed for NP production.…”

Section: Introductionmentioning

confidence: 99%

LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis inPhotorhabdusandXenorhabdus

Heinrich

Hirschmann

Neubacher

et al. 2017

PeerJ

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The Gram-negative bacteria Photorhabdus and Xenorhabdus are known to produce a variety of different natural products (NP). These compounds play different roles since the bacteria live in symbiosis with nematodes and are pathogenic to insect larvae in the soil. Thus, a fine tuned regulatory system controlling NP biosynthesis is indispensable. Global regulators such as Hfq, Lrp, LeuO and HexA have been shown to influence NP production of Photorhabdus and Xenorhabdus. Additionally, photopyrones as quorum sensing (QS) signals were demonstrated to be involved in the regulation of NP production in Photorhabdus. In this study, we investigated the role of another possible QS signal, autoinducer-2 (AI-2), in regulation of NP production. The AI-2 synthase (LuxS) is widely distributed within the bacterial kingdom and has a dual role as a part of the activated methyl cycle pathway, as well as being responsible for AI-2 precursor production. We deleted luxS in three different entomopathogenic bacteria and compared NP levels in the mutant strains to the wild type (WT) but observed no difference to the WT strains. Furthermore, the absence of the small regulatory RNA micA, which is encoded directly upstream of luxS, did not influence NP levels. Phenotypic differences between the P. luminescens luxS deletion mutant and an earlier described luxS deficient strain of P. luminescens suggested that two phenotypically different strains have evolved in different laboratories.

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Section: Introductionmentioning

confidence: 99%

LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis inPhotorhabdusandXenorhabdus

Heinrich

Hirschmann

Neubacher

et al. 2017

PeerJ

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“…Furthermore, nearly no production of secondary metabolites and the inability to support symbiosis with nematodes was observed for the 1°Δ hfq mutant. A double deletion of hfq and hexA restored secondary metabolite production as well as the recovery of infective juveniles to nematodes [34]. However, we observed enhanced HexA levels and increased promoter activity of hfq in 2° cells.…”

Section: Discussionmentioning

confidence: 58%

“…This is supported by the finding that a deletion of hfq in P . luminescens 1° cells caused a drastic increase in hexA expression [34]. Furthermore, nearly no production of secondary metabolites and the inability to support symbiosis with nematodes was observed for the 1°Δ hfq mutant.…”

Section: Discussionmentioning

confidence: 99%

HexA is a versatile regulator involved in the control of phenotypic heterogeneity of Photorhabdus luminescens

et al. 2017

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Phenotypic heterogeneity in microbial communities enables genetically identical organisms to behave differently even under the same environmental conditions. Photorhabdus luminescens, a bioluminescent Gram-negative bacterium, contains a complex life cycle, which involves a symbiotic interaction with nematodes as well as a pathogenic association with insect larvae. P. luminescens exists in two distinct phenotypic cell types, designated as the primary (1°) and secondary (2°) cells. The 1° cells are bioluminescent, pigmented and can support nematode growth and development. Individual 1° cells undergo phenotypic switching after prolonged cultivation and convert to 2° cells, which lack the 1° specific phenotypes. The LysR-type regulator HexA has been described as major regulator of this switching process. Here we show that HexA controls phenotypic heterogeneity in a versatile way, directly and indirectly. Expression of hexA is enhanced in 2° cells, and the corresponding regulator inhibits 1° specific traits in 2° cells. HexA does not directly affect bioluminescence, a predominant 1° specific phenotype. Since the respective luxCDABE operon is repressed at the post-transcriptional level and transcriptional levels of the RNA chaperone gene hfq are also enhanced in 2° cells, small regulatory RNAs are presumably involved that are under control of HexA. Another phenotypic trait that is specific for 1° cells is quorum sensing mediated cell clumping. The corresponding pcfABCDEF operon could be identified as the first direct target of HexA, since the regulator binds to the pcfA promoter region and thereby blocks expression of the target operon. In summary, our data show that HexA fulfills the task as repressor of 1° specific features in 2° cells in a versatile way and gives first insights into the complexity of regulating phenotypic heterogeneity in Photorhabdus bacteria.

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“…In hfq mutants of several strains analysed so far, all natural products were reduced 10 to 100-fold, most of them below the limit of detection (Tobias 2017). Hfq is known for binding small regulatory RNAs and deliver them to target mRNAs and thereby can activate or reduce protein levels.…”

Section: Buchmann Institute For Molecular Life Sciences (Bmls) Goethmentioning

confidence: 99%

1st Gießen Symposium of Insect Biotechnology, October 9-10, 2017 (published online)

2017

Zeitschrift Für Naturforschung C

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The genome of entomopathogenic bacteria of the genera Xenorhabdus and Photorhabdus encodes for up to 25 biosynthesis gene clusters (BGCs), representing up to 7.5% of the total genome. While several natural products have been identified and isolated from these bacteria during the last ten years due to efforts from several labs (Bode 2009, Challinor and Bode 2016, Vizcaino 2013, the majority of these compounds are still unknown. Therefore, these natural products are not accessible for a detailed analysis of their function in the natural ecosystem or as drugs in a more applied way (antibiotics, anticancer compounds, biotechnology etc) and methods for faster access to these natural products is desirable.We have analysed the deletion of known global regulators from Gram-negative bacteria on the natural product biosynthesis in Xenorhabdus and Photorhabdus (Engel 2017) and did identify the RNA chaperon Hfq playing a major role in natural product biosynthesis. In hfq mutants of several strains analysed so far, all natural products were reduced 10 to 100-fold, most of them below the limit of detection (Tobias 2017). Hfq is known for binding small regulatory RNAs and deliver them to target mRNAs and thereby can activate or reduce protein levels. When we applied our well-established promoter exchange approach (Bode 2015) to these hfq mutants, we were able to produce only the expected compound class upon activation of the promoter. We could transform the wildtype strains (as producers of multiple compounds) via the hfq strains (as no-producers of any compound) into single producers of a desired natural product class. Since an extract generated from these strains contains just one compound class, it can be tested directly against a variety of different targets allowing a simplified functional assignment of its biological function and without actual isolation of the natural product.Moreover, since the natural product can be produced on-demand in its natural environment due to its inducible promoter, the determination of the individual compound's contribution and role in the overall ecosystem can be addressed easily.As an additional way to generate chemical diversity from microorganisms, we have developed the eXchange Unit (XU) technology that allows the simple assembly of building blocks derived from natural non-ribosomal peptide synthetases (NRPS) to generate cyclic, linear, acylated peptides and/or peptides containing D-amino acids. Due to the definition of the XU and their assembly at a specific sequence, the yields even for non-natural peptides are between 1-40 mg/L in E. coli enabling detailed bioactivity testing. The XU technology can also be applied to the original producers enabling the simple modification of NRPS encoding BGCs as well as the artificial fusion of adjacent BGCs.Both, the latest results about hfq mediated production of individual compound classes and the XU technology will be presented. Justus-Liebig-University Giessen, Bioinformatics and Systems Biology, 35392 Gießen, Germany Corresponding author...

show abstract

Photorhabdus‐nematode symbiosis is dependent on hfq‐mediated regulation of secondary metabolites

Cited by 63 publications

References 61 publications

LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis inPhotorhabdusandXenorhabdus

LuxS-dependent AI-2 production is not involved in global regulation of natural product biosynthesis inPhotorhabdusandXenorhabdus

HexA is a versatile regulator involved in the control of phenotypic heterogeneity of Photorhabdus luminescens

1st Gießen Symposium of Insect Biotechnology, October 9-10, 2017 (published online)

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