Phylogenetic analysis of the salinipostin γ-butyrolactone gene cluster uncovers new potential for bacterial signalling-molecule diversity.
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ABSTRACT:
SUBMITTER: Creamer KE
PROVIDER: S-EPMC8209734 | biostudies-literature | 2021 May
REPOSITORIES: biostudies-literature
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Phylogenetic analysis of the salinipostin γ-butyrolactone gene cluster uncovers new potential for bacterial signalling-molecule diversity.
Creamer Kaitlin E KE Kudo Yuta Y Moore Bradley S BS Jensen Paul R PR
Microbial genomics 20210501 5
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Project description:Rhodococcus genome sequence analysis has revealed a surprisingly large (and unexplored) potential for the production of secondary metabolites. Also, putative γ-butyrolactone gene clusters have been identified in some Rhodococci. These signalling molecules are known to regulate secondary metabolism in Streptomyces. This work provides evidence for synthesis of a γ-butyrolactone(-like) molecule by Rhodococci (RJB), the first report in the Rhodococcus genus. The Rhodococcus jostii RHA1 RJB molecule was detected by a reporter system based on the γ-butyrolactone receptor protein (ScbR) of Streptomyces coelicolor. This RJB is structurally identical to 6-dehydro SCB2, the predicted precursor of the S. coelicolor γ-butyrolactone SCB2. The R. jostii RHA1 key RJB biosynthesis gene was identified (gblA): Deletion of gblA resulted in complete loss of RJB synthesis whereas higher RJB levels were detected when gblA was overexpressed. Interaction of the RJB molecule with ScbR indicates that communication may occur between these two Actinomycete genera in their natural habitat. Furthermore, RJB may provide a highly relevant tool for awakening cryptic secondary metabolic gene clusters in Rhodococci. This study provides preliminary evidence that R. jostii RHA1 indeed synthesizes diffusible molecules with antimicrobial activity, but a possible role for RJB in this remains to be established.
| S-EPMC5735094 | biostudies-literature
Project description:BackgroundThe control of antibiotic production in Streptomyces coelicolor A3(2) involves complicated regulatory networks with multiple regulators controlling the expression of antibiotic biosynthetic pathways. One such regulatory network is that of the γ-butyrolactones, the so-called S. coelicolor butanolide (SCB) system. The γ-butyrolactones in this system serve as signalling molecules and bind to the receptor protein ScbR, releasing the repression of its target genes. The resulting expression changes affect the production of the two pigmented antibiotics Act and Red, as well as the transcription of the cpk antibiotic biosynthesis gene cluster and the synthesis of the γ-butyrolactones themselves.ResultsWe identified a natural variant of ScbR in S. coelicolor (ScbRM600) that differs from ScbR in the genome-sequenced strain M145 (ScbRM145) by a single amino acid change, R120S. ScbRM600 is impaired in its DNA binding ability and alters the expression of the pathway-specific regulatory genes of the red and cpk antibiotic biosynthesis gene clusters. Also, expression of the γ-butyrolactone biosynthesis gene scbA and production of the signalling molecules is slightly reduced.ConclusionsThe γ-butyrolactone receptor, ScbR, plays a key role in the SCB regulatory cascade and in determining the onset of the expression of the antibiotic regulatory genes.
| S-EPMC3461410 | biostudies-literature
Project description:Bacterial hormones, such as the iconic gamma-butyrolactone A-factor, are essential signaling molecules that regulate diverse physiological processes, including specialized metabolism. These low molecular weight compounds are common in Streptomyces species and display species-specific structural differences. Recently, unusual gamma-butyrolactone natural products called salinipostins were isolated from the marine actinomycete genus Salinispora based on their antimalarial properties. As the salinipostins possess a rare phosphotriester motif of unknown biosynthetic origin, we set out to explore its construction by the widely conserved 9-gene spt operon in Salinispora species. We show through a series of in vivo and in vitro studies that the spt gene cluster dually encodes the salinipostins and newly identified natural A-factor-like gamma-butyrolactones (Sal-GBLs). Remarkably, homologous biosynthetic gene clusters are widely distributed among many actinomycete genera, including Streptomyces, suggesting the significance of this operon in bacteria.
| S-EPMC8217639 | biostudies-literature
Project description:γ-Butyrolactone and γ-butyrolactam were reacted in the superacidic systems XF/MF5 (X=H, D; M=As, Sb). Salts of the monoprotonated species of γ-butyrolactone were obtained in terms of [(CH2 )3 OCOH]+ [AsF6 ]- , [(CH2 )3 OCOH]+ [SbF6 ]- and [(CH2 )3 OCOD]+ [AsF6 ]- and the analogous lactam salts in terms of [(CH2 )3 NHCOH]+ [AsF6 ]- , [(CH2 )3 NHCOH]+ [SbF6 ]- and [(CH2 )3 NDCOD]+ [AsF6 ]- . The salts were characterized by low temperature Raman and infrared spectroscopy and for both protonated hexafluoridoarsenates, [(CH2 )3 OCOH]+ [AsF6 ]- and [(CH2 )3 NHCOH]+ [AsF6 ]- , single-crystal X-ray structure analyses were conducted. In addition to the experimental results, quantum chemical calculations were performed on the B3LYP/aug-cc-pVTZ level of theory. As in both crystal structures C⋅⋅⋅F contacts were observed, the nature of these contacts is discussed with Mapped Electrostatic Potential as a rate of strength.
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Project description:Actinomycetes are prolific producers of secondary metabolites with diverse bioactivities. Secondary metabolism in actinomycetes is regulated by signalling molecules, often termed "bacterial hormones." In Streptomyces griseus, the γ-butyrolactone (GBL) A-factor (1) plays a key role in regulating secondary metabolism, including streptomycin production. The widespread presence of afsA, the gene encoding A-factor synthase, suggests that GBLs are a major class of signalling molecules in actinomycetes. However, their identification is hindered by the requirement for large-scale cultures. This study presents two methodologies for identifying natural GBLs. First, a resin-assisted culture method combined with MS-guided screening enabled the isolation and structural determination of GBLs (2-5) from smaller-scale cultures. Second, a chemoenzymatic synthesis method involving one-pot three enzymatic reactions was developed, allowing the production of GBL standards (10a-10l). Using these standards, HR-LCMS analysis of 31 strains across 10 actinomycetes genera identified GBLs in nearly half of the tested strains, including genera where GBLs were detected for the first time. Chiral HPLC analysis further revealed the presence of the (3S)-isomer of GBL (11), an enantiomer of known GBLs. This study uncovers the widespread distribution and structural diversity of GBLs among actinomycetes, providing insights into their regulatory roles and potential for activating secondary metabolism, which may facilitate the discovery of new natural products.
| S-EPMC11877004 | biostudies-literature
Project description:BackgroundMicrobes must sense environmental stresses, transduce these signals and mount protective responses to survive in hostile environments. In this study we have tested the hypothesis that fungal stress signalling pathways have evolved rapidly in a niche-specific fashion that is independent of phylogeny. To test this hypothesis we have compared the conservation of stress signalling molecules in diverse fungal species with their stress resistance. These fungi, which include ascomycetes, basidiomycetes and microsporidia, occupy highly divergent niches from saline environments to plant or mammalian hosts.ResultsThe fungi displayed significant variation in their resistance to osmotic (NaCl and sorbitol), oxidative (H2O2 and menadione) and cell wall stresses (Calcofluor White and Congo Red). There was no strict correlation between fungal phylogeny and stress resistance. Rather, the human pathogens tended to be more resistant to all three types of stress, an exception being the sensitivity of Candida albicans to the cell wall stress, Calcofluor White. In contrast, the plant pathogens were relatively sensitive to oxidative stress. The degree of conservation of osmotic, oxidative and cell wall stress signalling pathways amongst the eighteen fungal species was examined. Putative orthologues of functionally defined signalling components in Saccharomyces cerevisiae were identified by performing reciprocal BLASTP searches, and the percent amino acid identities of these orthologues recorded. This revealed that in general, central components of the osmotic, oxidative and cell wall stress signalling pathways are relatively well conserved, whereas the sensors lying upstream and transcriptional regulators lying downstream of these modules have diverged significantly. There was no obvious correlation between the degree of conservation of stress signalling pathways and the resistance of a particular fungus to the corresponding stress.ConclusionOur data are consistent with the hypothesis that fungal stress signalling components have undergone rapid recent evolution to tune the stress responses in a niche-specific fashion.
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Project description:From Streptomyces virginiae, in which production of streptogramin antibiotic virginiamycin M(1) and S is tightly regulated by a low-molecular-weight Streptomyces hormone called virginiae butanolide (VB), which is a member of the gamma-butyrolactone autoregulators, the hormone biosynthetic gene (barS1) was cloned and characterized by heterologous expression in Escherichia coli and by gene disruption in S. virginiae. The barS1 gene (a 774-bp open reading frame encoding a 257-amino-acid protein [M(r), 27,095]) is situated in the 10-kb regulator island surrounding the VB-specific receptor gene, barA. The deduced BarS1 protein is weakly homologous to beta-ketoacyl-acyl carrier protein/coenzyme A reductase and belongs to the superfamily of short-chain alcohol dehydrogenase. The function of the BarS1 protein in VB biosynthesis was confirmed by BarS1-dependent in vitro conversion of 6-dehydro-VB-A to VB-A, the last catalytic step in VB biosynthesis. Of the four possible enantiomeric products from racemic 6-dehydro-VB-A as a substrate, only the natural enantiomer of (2R,3R,6S)-VB-A was produced by the purified recombinant BarS1 (rBarS1), indicating that rBarS1 is the stereospecific reductase recognizing (3R)-isomer as a substrate and reducing it stereospecifically to the (6S) product. In the DeltabarS1 mutant created by homologous recombination, the production of VB as well as the production of virginiamycin was lost. The production of virginiamycin by the DeltabarS1 mutant was fully recovered by the external addition of VB to the culture, which indicates that the barS1 gene is essential in the biosynthesis of the autoregulator VBs in S. virginiae and that the failure of virginiamycin production was a result of the loss of VB production.
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