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Microbiology Resource Announcements Feb 2020We report the draft genome sequence of sp. strain LD120, which was isolated from a brown macroalga in the Baltic Sea. The genome of this marine subgroup bacterium...
We report the draft genome sequence of sp. strain LD120, which was isolated from a brown macroalga in the Baltic Sea. The genome of this marine subgroup bacterium harbors biosynthetic gene clusters for toxic metabolites typically produced by members of this subgroup, including 2,4-diacetylphloroglucinol, pyoluteorin, and rhizoxin analogs.
PubMed: 32079630
DOI: 10.1128/MRA.01305-19 -
Environmental Microbiology Jan 2024Rhizopus microsporus often lives in association with bacterial and viral symbionts that alter its biology. This fungal model represents an example of the complex...
Rhizopus microsporus often lives in association with bacterial and viral symbionts that alter its biology. This fungal model represents an example of the complex interactions established among diverse organisms in functional holobionts. We constructed a Genome-Scale Model (GSM) of the fungal-bacterial-viral holobiont (iHol). We employed a constraint-based method to calculate the metabolic fluxes to decipher the metabolic interactions of the symbionts with their host. Our computational analyses of iHol simulate the holobiont's growth and the production of the toxin rhizoxin. Analyses of the calculated fluxes between R. microsporus in symbiotic (iHol) versus asymbiotic conditions suggest that changes in the lipid and nucleotide metabolism of the host are necessary for the functionality of the holobiont. Glycerol plays a pivotal role in the fungal-bacterial metabolic interaction, as its production does not compromise fungal growth, and Mycetohabitans bacteria can efficiently consume it. Narnavirus RmNV-20S and RmNV-23S affected the nucleotide metabolism without impacting the fungal-bacterial symbiosis. Our analyses highlighted the metabolic stability of Mycetohabitans throughout its co-evolution with the fungal host. We also predicted changes in reactions of the bacterial metabolism required for the active production of rhizoxin. This iHol is the first GSM of a fungal holobiont.
Topics: Macrolides; Rhizopus; Bacteria; Nucleotides; Symbiosis
PubMed: 38072824
DOI: 10.1111/1462-2920.16551 -
Chemical Communications (Cambridge,... Jun 2015The versatility of the branching module of the rhizoxin polyketide synthase was tested in an in vitro enzyme assay with a polyketide mimic and branched...
The versatility of the branching module of the rhizoxin polyketide synthase was tested in an in vitro enzyme assay with a polyketide mimic and branched (di)methylmalonyl-CoA extender units. Comparison of the products with synthetic reference compounds revealed that the module is able to stereoselectively introduce two branches in one step by a Michael addition-lactonisation sequence, thus expanding the scope of previously studied PKS systems.
Topics: Acyl Coenzyme A; Antibiotics, Antineoplastic; Macrolides; Polyketide Synthases
PubMed: 25994388
DOI: 10.1039/c5cc03085d -
Angewandte Chemie (International Ed. in... Feb 2024Modular polyketide synthases (PKSs) are giant assembly lines that produce an impressive range of biologically active compounds. However, our understanding of the...
Modular polyketide synthases (PKSs) are giant assembly lines that produce an impressive range of biologically active compounds. However, our understanding of the structural dynamics of these megasynthases, specifically the delivery of acyl carrier protein (ACP)-bound building blocks to the catalytic site of the ketosynthase (KS) domain, remains severely limited. Using a multipronged structural approach, we report details of the inter-domain interactions after C-C bond formation in a chain-branching module of the rhizoxin PKS. Mechanism-based crosslinking of an engineered module was achieved using a synthetic substrate surrogate that serves as a Michael acceptor. The crosslinked protein allowed us to identify an asymmetric state of the dimeric protein complex upon C-C bond formation by cryo-electron microscopy (cryo-EM). The possible existence of two ACP binding sites, one of them a potential "parking position" for substrate loading, was also indicated by AlphaFold2 predictions. NMR spectroscopy showed that a transient complex is formed in solution, independent of the linker domains, and photochemical crosslinking/mass spectrometry of the standalone domains allowed us to pinpoint the interdomain interaction sites. The structural insights into a branching PKS module arrested after C-C bond formation allows a better understanding of domain dynamics and provides valuable information for the rational design of modular assembly lines.
Topics: Polyketide Synthases; Cryoelectron Microscopy; Binding Sites; Catalytic Domain; Acyl Carrier Protein
PubMed: 38134222
DOI: 10.1002/anie.202315850