Extracellular and intracellular lanthanide accumulation in the methylotroph Beijerinckiaceae bacterium RH AL1

Recent work in Methylorubrum extorquens AM1 identified intracellular, cytoplasmic lanthanide storage in an organism that harnesses these metals for its metabolism. Here, we describe the extracellular and intracellular accumulation of lanthanides in Beijerinckiaceae bacterium RH AL1, a newly isolated and recently characterized methylotroph. Using ultrathin-section transmission electron microscopy (TEM), freeze-fracture TEM (FFTEM), and energy-dispersive X-ray spectroscopy, we demonstrated that strain RH AL1 accumulates lanthanides extracellularly at outer membrane vesicles (OMVs) and stores them in the periplasm. High-resolution elemental analyses of biomass samples revealed that strain RH AL1 can accumulate ions of different lanthanide species with a preference for heavier lanthanides. Its methanol oxidation machinery is supposably adapted to light lanthanides, and their selective uptake is mediated by dedicated uptake mechanisms. Based on RNAseq analysis, these presumably include the previously characterized TonB-ABC transport system encoded by the lut-cluster, but eventually also a type VI secretion system. A high constitutive expression of genes coding for lanthanide-dependent enzymes suggested that strain RH AL1 maintains a stable transcript pool to flexibly respond to changing lanthanide availability. Genes coding for lanthanide-dependent enzymes are broadly distributed taxonomically. Our results support the hypothesis that central aspects of lanthanide-dependent metabolism partially differ between the various taxa. Importance: Although multiple pieces of evidence have been added to the puzzle of lanthanide-dependent metabolism, we are still far from understanding the physiological role of lanthanides. Given how widespread lanthanide-dependent enzymes are, only limited information is available with respect to how lanthanides are taken up and stored in an organism. Our research complements work in commonly studied model organisms and showed the localized storage of lanthanides in the periplasm. This storage occurred at comparably low concentrations. Strain RH AL1 is able to accumulate lanthanide ions extracellularly and to selectively utilize lighter lanthanides. Beijerinckiaceae bacterium RH AL1 might be an attractive target for developing biorecovery strategies to win these economically highly demanded metals in more environmentally friendly ways.

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Hemin Binding Protein C Is Found in Outer Membrane Vesicles and Protects Bartonella henselae against Toxic Concentrations of Hemin

Infection and Immunity ◽

10.1128/iai.05769-11 ◽

2012 ◽

Vol 80 (3) ◽

pp. 929-942 ◽

Cited By ~ 22

Author(s):

Julie A. Roden ◽

Derek H. Wells ◽

Bruno B. Chomel ◽

Rickie W. Kasten ◽

Jane E. Koehler

Keyword(s):

Outer Membrane ◽

Protein C ◽

High Efficiency ◽

Binding Protein ◽

Constitutive Expression ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Mammalian Host ◽

Content Type ◽

Arthropod Vector

Bartonellaspecies are Gram-negative, emerging bacterial pathogens found in two distinct environments. In the gut of the obligately hematophagous arthropod vector, bartonellae are exposed to concentrations of heme that are toxic to other bacteria. In the bloodstream of the mammalian host, access to heme and iron is severely restricted. Bartonellae have unusually high requirements for heme, which is their only utilizable source of iron. Although heme is essential forBartonellasurvival, little is known about genes involved in heme acquisition and detoxification. We developed a strategy for high-efficiency transposon mutagenesis to screen for genes inB. henselaeheme binding and uptake pathways. We identified aB. henselaetransposon mutant that constitutively expresses the hemin binding protein C (hbpC) gene. In the wild-type strain, transcription ofB. henselae hbpCwas upregulated at arthropod temperature (28°C), compared to mammalian temperature (37°C). In the mutant strain, temperature-dependent regulation was absent. We demonstrated that HbpC binds hemin and localizes to theB. henselaeouter membrane and outer membrane vesicles. Overexpression ofhbpCinB. henselaeincreased resistance to heme toxicity, implicating HbpC in protection ofB. henselaefrom the toxic levels of heme present in the gut of the arthropod vector. Experimental inoculation of cats withB. henselaestrains demonstrated that both constitutive expression and deletion ofhbpCaffect the ability ofB. henselaeto infect the cat host. Modulation ofhbpCexpression appears to be a strategy employed byB. henselaeto survive in the arthropod vector and the mammalian host.

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T6SS secretes an LPS-binding effector to recruit OMVs for exploitative competition and horizontal gene transfer

The ISME Journal ◽

10.1038/s41396-021-01093-8 ◽

2021 ◽

Author(s):

Changfu Li ◽

Lingfang Zhu ◽

Dandan Wang ◽

Zhiyan Wei ◽

Xinwei Hao ◽

...

Keyword(s):

Gene Transfer ◽

Horizontal Gene Transfer ◽

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Membrane Receptors ◽

Receptor Interaction ◽

Bacterial Cells ◽

Type Vi Secretion System ◽

Lps Binding

AbstractOuter membrane vesicles (OMVs) can function as nanoscale vectors that mediate bacterial interactions in microbial communities. How bacteria recognize and recruit OMVs inter-specifically remains largely unknown, thus limiting our understanding of the complex physiological and ecological roles of OMVs. Here, we report a ligand-receptor interaction-based OMV recruitment mechanism, consisting of a type VI secretion system (T6SS)-secreted lipopolysaccharide (LPS)-binding effector TeoL and the outer membrane receptors CubA and CstR. We demonstrated that Cupriavidus necator T6SS1 secretes TeoL to preferentially associate with OMVs in the extracellular milieu through interactions with LPS, one of the most abundant components of OMVs. TeoL associated with OMVs can further bind outer membrane receptors CubA and CstR, which tethers OMVs to the recipient cells and allows cargo to be delivered. The LPS-mediated mechanism enables bacterial cells to recruit OMVs derived from different species, and confers advantages to bacterial cells in iron acquisition, interbacterial competition, and horizontal gene transfer (HGT). Moreover, our findings provide multiple new perspectives on T6SS functionality in the context of bacterial competition and HGT, through the recruitment of OMVs.

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The Effect of Helicobacter Pylori Outer Membrane Vesicles On Vacuolation in Gastric and Colonic Epithelial Cells

Endoscopy ◽

10.1055/s-2006-956848 ◽

2006 ◽

Vol 38 (11) ◽

Author(s):

EM Mullaney ◽

AM Terres ◽

DP Kelleher

Keyword(s):

Helicobacter Pylori ◽

Epithelial Cells ◽

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Colonic Epithelial Cells

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Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

10.26434/chemrxiv.8282204.v1 ◽

2019 ◽

Author(s):

Jiajun Wang ◽

Rémi Terrasse ◽

Jayesh Arun Bafna ◽

Lorraine Benier ◽

Mathias Winterhalter

Keyword(s):

Outer Membrane ◽

Lipid Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Multi Drug Resistance ◽

Gram Negative Bacteria ◽

Membrane Channels ◽

Gram Negative ◽

Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from Escherichia coli, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (kon) and lower dissociation (koff) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

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