scholarly journals Effects of an EPS Biosynthesis Gene Cluster of Paenibacillus polymyxa WLY78 on Biofilm Formation and Nitrogen Fixation under Aerobic Conditions

2021 ◽  
Vol 9 (2) ◽  
pp. 289
Author(s):  
Xiaojuan He ◽  
Qin Li ◽  
Nan Wang ◽  
Sanfeng Chen
Keyword(s):  
Extracellular Matrix ◽  
Biofilm Formation ◽  
Paenibacillus Polymyxa ◽  
Gene Clusters ◽  
Bacterial Biofilm ◽  
Biosynthesis Gene Cluster ◽  
Putative Gene ◽  
Aerobic Conditions ◽  
Biosynthesis Gene ◽  
Paenibacillus Species

Exopolysaccharides (EPS) are of high significance in bacterial biofilm formation. However, the effects of EPS cluster(s) on biofilm formation in Paenibacillus species are little known. In this study, we have shown that Paenibacillus polymyxa WLY78, a N2-fixing bacterium, can form biofilm. EPS is the major component of the extracellular matrix. The genome of P. polymyxa WLY78 contains two putative gene clusters (designated pep-1 cluster and pep-2 cluster). The pep-1 cluster is composed of 12 putative genes (pepO-lytR) co-located in a 13 kb region. The pep-2 cluster contains 17 putative genes (pepA-pepN) organized as an operon in a 20 kb region. Mutation analysis reveals that the pep-2 cluster is involved in EPS biosynthesis and biofilm formation. Disruption of the pep-2 cluster also leads to the enhancement of motility and change of the colony morphology. In contrast, disruption of the pep-1 cluster does not affect EPS synthesis or biofilm formation. More importantly, the biofilm allowed P. polymyxa WLY78 to fix nitrogen in aerobic conditions, suggesting that biofilm may provide a microaerobic environment for nitrogenase synthesis and activity.

scholarly journals Putative Exopolysaccharide Synthesis Genes Influence Pseudomonas aeruginosa Biofilm Development

2004 ◽  
Vol 186 (14) ◽  
pp. 4449-4456 ◽  
Author(s):  
Masanori Matsukawa ◽  
E. P. Greenberg
Keyword(s):  
Extracellular Matrix ◽  
Pseudomonas Aeruginosa ◽  
Genomic Sequence ◽  
Gene Clusters ◽  
Strain Pao1 ◽  
Biosynthesis Gene Cluster ◽  
Biosynthesis Gene ◽  
The Matrix ◽  
Biofilm Development ◽  
A Minor

ABSTRACT An analysis of the Pseudomonas aeruginosa genomic sequence revealed three gene clusters, PA1381-1393, PA2231-2240, and PA3552-3558, in addition to the alginate biosynthesis gene cluster, which appeared to encode functions for exopolysaccharide (EPS) biosynthesis. Recent evidence indicates that alginate is not a significant component of the extracellular matrix in biofilms of the sequenced P. aeruginosa strain PAO1. We hypothesized that at least one of the three potential EPS gene clusters revealed by genomic sequencing is an important component of P. aeruginosa PAO1 biofilms. Thus, we constructed mutants with chromosomal insertions in PA1383, PA2231, and PA3552. The mutant with a PA2231 defect formed thin unstructured abnormal biofilms. The PA3552 mutant formed structured biofilms that appeared different from those formed by the parent, and the PA1383 mutant formed structured biofilms that were indistinguishable from those formed by the parent. Consistent with a previous report, we found that polysaccharides were one component of the extracellular matrix, which also contained DNA. We suggest that the genes that were inactivated in our PA2231 mutant are required for the production of an EPS, which, although it may be a minor constituent of the matrix, is critical for the formation of P. aeruginosa PAO1 biofilms.

scholarly journals A Diverse Repertoire of Exopolysaccharide Biosynthesis Gene Clusters in Lactobacillus Revealed by Comparative Analysis in 106 Sequenced Genomes

2019 ◽  
Vol 7 (10) ◽  
pp. 444 ◽  
Author(s):  
Dipti Deo ◽  
Dimple Davray ◽  
Ram Kulkarni
Keyword(s):  
Biofilm Formation ◽  
Gene Clusters ◽  
High Variability ◽  
Protein Families ◽  
Free Living ◽  
Biosynthesis Gene ◽  
Exopolysaccharide Biosynthesis ◽  
Pharmaceutical Industries ◽  
Living Group ◽  
Core Genes

Production of exopolysaccharides (EPS) is one of the unique features of Lactobacillus genus. EPS not only have many physiological roles such as in stress tolerance, quorum sensing and biofilm formation, but also have numerous applications in the food and pharmaceutical industries. In this study, we identified and compared EPS biosynthesis gene clusters in 106 sequenced Lactobacillus genomes representing 27 species. Of the 146 identified clusters, only 41 showed the typical generic organization of genes as reported earlier. Hierarchical clustering showed highly varied nature of the clusters in terms of the gene composition; nonetheless, habitat-wise grouping was observed for the gene clusters from host-adapted and nomadic strains. Of the core genes required for EPS biosynthesis, epsA, B, C, D and E showed higher conservation, whereas gt, wzx and wzy showed high variability in terms of the number and composition of the protein families. Analysis of the distribution pattern of the protein families indicated a higher proportion of mutually exclusive families in clusters from host-adapted and nomadic strains, whereas those from the free-living group had very few unique families. Taken together, this analysis highlights high variability in the EPS gene clusters amongst Lactobacillus with some of their properties correlated to the habitats.

scholarly journals Deacetylation of Fungal Exopolysaccharide Mediates Adhesion and Biofilm Formation

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Mark J. Lee ◽  
Alexander M. Geller ◽  
Natalie C. Bamford ◽  
Hong Liu ◽  
Fabrice N. Gravelat ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Bacterial Biofilm ◽  
Invasive Infection ◽  
Biosynthetic Gene ◽  
Adhesive Properties

ABSTRACTThe moldAspergillus fumigatuscauses invasive infection in immunocompromised patients. Recently, galactosaminogalactan (GAG), an exopolysaccharide composed of galactose andN-acetylgalactosamine (GalNAc), was identified as a virulence factor required for biofilm formation. The molecular mechanisms underlying GAG biosynthesis and GAG-mediated biofilm formation were unknown. We identified a cluster of five coregulated genes that were dysregulated in GAG-deficient mutants and whose gene products share functional similarity with proteins that mediate the synthesis of the bacterial biofilm exopolysaccharide poly-(β1-6)-N-acetyl-d-glucosamine (PNAG). Bioinformatic analyses suggested that the GAG cluster geneagd3encodes a protein containing a deacetylase domain. Because deacetylation ofN-acetylglucosamine residues is critical for the function of PNAG, we investigated the role of GAG deacetylation in fungal biofilm formation. Agd3 was found to mediate deacetylation of GalNAc residues within GAG and render the polysaccharide polycationic. As with PNAG, deacetylation is required for the adherence of GAG to hyphae and for biofilm formation. Growth of the Δagd3mutant in the presence of culture supernatants of the GAG-deficient Δuge3mutant rescued the biofilm defect of the Δagd3mutant and restored the adhesive properties of GAG, suggesting that deacetylation is an extracellular process. The GAG biosynthetic gene cluster is present in the genomes of members of thePezizomycotinasubphylum of theAscomycotaincluding a number of plant-pathogenic fungi and a single basidiomycete species,Trichosporon asahii, likely a result of recent horizontal gene transfer. The current study demonstrates that the production of cationic, deacetylated exopolysaccharides is a strategy used by both fungi and bacteria for biofilm formation.IMPORTANCEThis study sheds light on the biosynthetic pathways governing the synthesis of galactosaminogalactan (GAG), which plays a key role inA. fumigatusvirulence and biofilm formation. We find that bacteria and fungi use similar strategies to synthesize adhesive biofilm exopolysaccharides. The presence of orthologs of the GAG biosynthetic gene clusters in multiple fungi suggests that this exopolysaccharide may also be important in the virulence of other fungal pathogens. Further, these studies establish a molecular mechanism of adhesion in which GAG interacts via charge-charge interactions to bind to both fungal hyphae and other substrates. Finally, the importance of deacetylation in the synthesis of functional GAG and the extracellular localization of this process suggest that inhibition of deacetylation may be an attractive target for the development of novel antifungal therapies.

scholarly journals A Rhizobiales-Specific Unipolar Polysaccharide Adhesin Contributes to Rhodopseudomonas palustris Biofilm Formation across Diverse Photoheterotrophic Conditions

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Ryan K. Fritts ◽  
Breah LaSarre ◽  
Ari M. Stoner ◽  
Amanda L. Posto ◽  
James B. McKinlay
Keyword(s):  
Biofilm Formation ◽  
Bacterial Species ◽  
Rhodopseudomonas Palustris ◽  
Gene Clusters ◽  
Growth Conditions ◽  
Organic Substrates ◽  
Biosynthesis Gene Cluster ◽  
Surface Attachment ◽  
Content Type ◽  
Animal Pathogens

ABSTRACT Bacteria predominantly exist as members of surfaced-attached communities known as biofilms. Many bacterial species initiate biofilms and adhere to each other using cell surface adhesins. This is the case for numerous ecologically diverse Alphaprotebacteria, which use polar exopolysaccharide adhesins for cell-cell adhesion and surface attachment. Here, we show that Rhodopseudomonas palustris, a metabolically versatile member of the alphaproteobacterial order Rhizobiales, contains a functional unipolar polysaccharide (UPP) biosynthesis gene cluster. Deletion of genes predicted to be critical for UPP biosynthesis and export abolished UPP production. We also found that R. palustris uses UPP to mediate biofilm formation across diverse photoheterotrophic growth conditions, wherein light and organic substrates are used to support growth. However, UPP was less important for biofilm formation during photoautotrophy, where light and CO2 support growth, and during aerobic respiration with organic compounds. Expanding our analysis beyond R. palustris, we examined the phylogenetic distribution and genomic organization of UPP gene clusters among Rhizobiales species that inhabit diverse niches. Our analysis suggests that UPP is a conserved ancestral trait of the Rhizobiales but that it has been independently lost multiple times during the evolution of this clade, twice coinciding with adaptation to intracellular lifestyles within animal hosts. IMPORTANCE Bacteria are ubiquitously found as surface-attached communities and cellular aggregates in nature. Here, we address how bacterial adhesion is coordinated in response to diverse environments using two complementary approaches. First, we examined how Rhodopseudomonas palustris, one of the most metabolically versatile organisms ever described, varies its adhesion to surfaces in response to different environmental conditions. We identified critical genes for the production of a unipolar polysaccharide (UPP) and showed that UPP is important for adhesion when light and organic substrates are used for growth. Looking beyond R. palustris, we performed the most comprehensive survey to date on the conservation of UPP biosynthesis genes among a group of closely related bacteria that occupy diverse niches. Our findings suggest that UPP is important for free-living and plant-associated lifestyles but dispensable for animal pathogens. Additionally, we propose guidelines for classifying the adhesins produced by various Alphaprotebacteria, facilitating future functional and comparative studies.

scholarly journals A Pseudoalteromonas clade with remarkable biosynthetic potential

2021 ◽  
Author(s):  
Rocky Chau ◽  
Leanne A. Pearson ◽  
Jesse Cain ◽  
John A. Kalaitzis ◽  
Brett A. Neilan
Keyword(s):  
Natural Products ◽  
Gene Cluster ◽  
Genome Mining ◽  
Gene Clusters ◽  
Average Density ◽  
Biologically Active ◽  
Biosynthesis Gene Cluster ◽  
Diverse Range ◽  
Siderophore Biosynthesis ◽  
Biosynthesis Gene

Pseudoalteromonas species produce a diverse range of biologically active compounds, including those biosynthesized by non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). Here we report the biochemical and genomic analysis of Pseudoalteromonas sp. HM-SA03, isolated from the blue-ringed octopus, Hapalochalaena sp. Genome mining for secondary metabolite pathways revealed seven putative NRPS/PKS biosynthesis gene clusters, including those for the biosynthesis of alterochromides, pseudoalterobactins, alteramides and four hitherto novel compounds. Among these was a novel siderophore biosynthesis gene cluster with unprecedented architecture (NRPS-PKS-NRPS-PKS-NRPS-PKS-NRPS). Alterochromide production in HM-SA03 was also confirmed by liquid chromatography-mass spectrometry. An investigation of the biosynthetic potential of 42 publicly available Pseudoalteromonas genomes indicated that some of these gene clusters are distributed throughout the genus. Through phylogenetic analysis, a particular subset of strains formed a clade with extraordinary biosynthetic potential, with an average density of ten biosynthesis gene clusters per genome. In contrast, the majority of Pseudoalteromonas strains outside this clade contained an average of three clusters encoding complex biosynthesis. These results highlight the under-explored potential of Pseudoalteromonas as a source of new natural products. Importance This study demonstrates that the Pseudoalteromonas strain, HM-SA03, isolated from the venomous blue-ringed octopus, Hapalochalaena sp., is a biosynthetically talented organism, capable of producing alterochromides and potentially six other specialized metabolites. We have identified a pseudoalterobactin biosynthesis gene cluster and proposed a pathway for the production of the associated siderophore. A novel siderophore biosynthesis gene cluster with unprecedented architecture was also identified in the HM-SA03 genome. Finally, we have demonstrated that HM-SA03 belongs to a phylogenetic clade of strains with extraordinary biosynthetic potential. While our results do not support a role of HM-SA03 in Hapalochalaena sp. venom (tetrodotoxin) production, they emphasize the untapped potential of Pseudoalteromonas as a source of novel natural products.

scholarly journals A Rhizobiales-specific unipolar polysaccharide adhesin contributes to Rhodopseudomonas palustris biofilm formation across diverse photoheterotrophic conditions

2016 ◽  
Author(s):  
Ryan K Fritts ◽  
Breah LaSarre ◽  
Ari M Stoner ◽  
Amanda L Posto ◽  
James B McKinlay
Keyword(s):  
Biofilm Formation ◽  
Bacterial Species ◽  
Rhodopseudomonas Palustris ◽  
Gene Clusters ◽  
Growth Conditions ◽  
Organic Substrates ◽  
Biosynthesis Gene Cluster ◽  
Surface Attachment ◽  
Animal Hosts ◽  
Surface Adhesins

Bacteria predominantly exist as members of surfaced-attached communities known as biofilms. Many bacterial species initiate biofilms and adhere to each other using cell surface adhesins. This is the case for numerous ecologically diverse α-proteobacteria, which use polar exopolysaccharide adhesins for cell-cell adhesion and surface attachment. Here, we show that Rhodopseudomonas palustris, a metabolically versatile member of the α-proteobacterial order Rhizobiales, encodes a functional unipolar polysaccharide (UPP) biosynthesis gene cluster. Deletion of genes predicted to be critical for UPP biosynthesis and export abolished UPP production. We also found that R. palustris uses UPP to mediate biofilm formation across diverse photoheterotrophic growth conditions, wherein light and organic substrates are used to support growth. However, UPP was less important for biofilm formation during photoautotrophy, where light and CO2 support growth, and during aerobic respiration with organic compounds. Expanding our analysis beyond R. palustris, we examined the phylogenetic distribution and genomic organization of UPP gene clusters among Rhizobiales species that inhabit diverse niches. Our analysis suggests that UPP is a conserved ancestral trait of the Rhizobiales but that it has been independently lost multiple times during the evolution of this clade, twice coinciding with adaptation to intracellular lifestyles within animal hosts.

scholarly journals The Swinholide Biosynthesis Gene Cluster from a Terrestrial Cyanobacterium, Nostoc sp. Strain UHCC 0450

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Anu Humisto ◽  
Jouni Jokela ◽  
Liwei Liu ◽  
Matti Wahlsten ◽  
Hao Wang ◽  
...  
Keyword(s):  
Natural Products ◽  
Actin Cytoskeleton ◽  
Gene Cluster ◽  
Marine Sponge ◽  
Gene Clusters ◽  
Fold Axis ◽  
Biosynthesis Gene Cluster ◽  
Content Type ◽  
Biosynthesis Gene ◽  
Axis Of Symmetry

ABSTRACT Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of a symbiotic heterotrophic proteobacterium. Here, we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp. strain UHCC 0450. We located the 85-kb trans -AT polyketide synthase (PKS) swinholide biosynthesis gene cluster from a draft genome of Nostoc sp. UHCC 0450. The swinholide and misakinolide biosynthesis gene clusters share an almost identical order of catalytic domains, with 85% nucleotide sequence identity, and they group together in phylogenetic analysis. Our results resolve speculation around the true producer of swinholides and demonstrate that bacteria belonging to two distantly related phyla both produce structural variants of the same natural product. In addition, we described a biosynthesis cluster from Anabaena sp. strain UHCC 0451 for the synthesis of the cytotoxic and antifungal scytophycin. All of these biosynthesis gene clusters were closely related to each other and created a group of cytotoxic macrolide compounds produced by trans -AT PKSs of cyanobacteria and proteobacteria. IMPORTANCE Many of the drugs in use today originate from natural products. New candidate compounds for drug development are needed due to increased drug resistance. An increased knowledge of the biosynthesis of bioactive compounds can be used to aid chemical synthesis to produce novel drugs. Here, we show that a terrestrial axenic culture of Nostoc cyanobacterium produces swinholides, which have been previously found only from marine sponge or samples related to them. Swinholides are polyketides with a 2-fold axis of symmetry, and they are potent cytotoxins that disrupt the actin cytoskeleton. We describe the biosynthesis gene clusters of swinholide from Nostoc cyanobacteria, as well as the related cytotoxic and antifungal scytophycin from Anabaena cyanobacteria, and we study the evolution of their trans -AT polyketide synthases. Interestingly, swinholide is closely related to misakinolide produced by a symbiotic heterotrophic proteobacterium, demonstrating that bacteria belonging to two distantly related phyla and different habitats can produce similar natural products.

scholarly journals Identification of a Polyketide Synthase Gene Responsible for Ascochitine Biosynthesis in Ascochyta fabae and Its Abrogation in Sister Taxa

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Wonyong Kim ◽  
Judith Lichtenzveig ◽  
Robert A. Syme ◽  
Angela H. Williams ◽  
Tobin L. Peever ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Secondary Metabolite ◽  
Polyketide Synthase ◽  
Animal Health ◽  
Gene Clusters ◽  
Biosynthesis Gene Cluster ◽  
Content Type ◽  
Pathogenicity Factor ◽  
Biosynthesis Gene ◽  
Ascochyta Fabae

ABSTRACT The polyketide-derived secondary metabolite ascochitine is produced by species in the Didymellaceae family, including but not restricted to Ascochyta species pathogens of cool-season food legumes. Ascochitine is structurally similar to the well-known mycotoxin citrinin and exhibits broad-spectrum phytotoxicity and antimicrobial activities. Here, we identified a polyketide synthase (PKS) gene (denoted pksAC) responsible for ascochitine production in the filamentous fungus Ascochyta fabae. Deletion of the pksAC prevented production of ascochitine and its derivative ascochital in A. fabae. The putative ascochitine biosynthesis gene cluster comprises 11 genes that have undergone rearrangement and gain-and-loss events relative to the citrinin biosynthesis gene cluster in Monascus ruber. Interestingly, we also identified pksAC homologs in two recently diverged species, A. lentis and A. lentis var. lathyri, that are sister taxa closely related to ascochitine producers such as A. fabae and A. viciae-villosae. However, nonsense mutations have been independently introduced in coding sequences of the pksAC homologs of A. lentis and A. lentis var. lathyri that resulted in loss of ascochitine production. Despite its reported phytotoxicity, ascochitine was not a pathogenicity factor in A. fabae infection and colonization of faba bean (Vicia faba L.). Ascochitine was mainly produced from mature hyphae at the site of pycnidial formation, suggesting a possible protective role of the compound against other microbial competitors in nature. This report highlights the evolution of gene clusters harnessing the structural diversity of polyketides and a mechanism with the potential to alter secondary metabolite profiles via single nucleotide polymorphisms in closely related fungal species. IMPORTANCE Fungi produce a diverse array of secondary metabolites, many of which are of pharmacological importance whereas many others are noted for mycotoxins, such as aflatoxin and citrinin, that can threaten human and animal health. The polyketide-derived compound ascochitine, which is structurally similar to citrinin mycotoxin, has been considered to be important for pathogenicity of legume-associated Ascochyta species. Here, we identified the ascochitine polyketide synthase (PKS) gene in Ascochyta fabae and its neighboring genes that may be involved in ascochitine biosynthesis. Interestingly, the ascochitine PKS genes in other legume-associated Ascochyta species have been mutated, encoding truncated PKSs. This indicated that point mutations may have contributed to genetic diversity for secondary metabolite production in these fungi. We also demonstrated that ascochitine is not a pathogenicity factor in A. fabae. The antifungal activities and production of ascochitine during sporulation suggested that it may play a role in competition with other saprobic fungi in nature.

scholarly journals Distribution and conservation of known secondary metabolite biosynthesis gene clusters in the genomes of geographically diverse Microcystis aeruginosa strains

2020 ◽  
Vol 71 (5) ◽  
pp. 701 ◽  
Author(s):  
Leanne A. Pearson ◽  
Nicholas D. Crosbie ◽  
Brett A. Neilan
Keyword(s):  
Gene Cluster ◽  
Secondary Metabolite ◽  
Microcystis Aeruginosa ◽  
Gene Clusters ◽  
Biologically Active ◽  
Biosynthesis Gene Cluster ◽  
Phosphatase Inhibitors ◽  
Biosynthesis Gene ◽  
Screening Study ◽  
Non Ribosomal Peptides

The cyanobacterium Microcystis aeruginosa has been linked to toxic blooms worldwide. In addition to producing hepatotoxic microcystins, many strains are capable of synthesising a variety of biologically active compounds, including protease and phosphatase inhibitors, which may affect aquatic ecosystems and pose a risk to their use. This study explored the distribution, composition and conservation of known secondary metabolite (SM) biosynthesis gene clusters in the genomes of 27 M. aeruginosa strains isolated from six different Köppen–Geiger climates. Our analysis identified gene clusters with significant homology to nine SM biosynthesis gene clusters spanning four different compound classes: non-ribosomal peptides, hybrid polyketide–non-ribosomal peptides, cyanobactins and microviridins. The aeruginosin, microviridin, cyanopeptolin and microcystin biosynthesis gene clusters were the most frequently observed, but hybrid polyketide–non-ribosomal peptide biosynthesis clusters were the most common class overall. Although some biogeographic relationships were observed, taxonomic markers and geography were not reliable indicators of SM biosynthesis cluster distribution, possibly due to previous genetic deletions or horizontal gene transfer events. The only cyanotoxin biosynthesis gene cluster identified in our screening study was the microcystin synthetase (mcy) gene cluster, suggesting that the production of non-microcystin cyanotoxins by this taxon, such as anatoxin-a or paralytic shellfish poison analogues, is either absent or rare.

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