Production of Outer Membrane Vesicles and Outer Membrane Tubes by Francisella novicida

McCaig, William D.; Koller, Antonius; Thanassi, David G.

doi:10.1128/jb.02007-12

Cited by 134 publications

(159 citation statements)

References 77 publications

(128 reference statements)

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“…strain Cs1-4 (26)(27)(28)(29). To extend and compare our findings, we surveyed distantly related species for OMTs by again using the lipophilic fluorescent dye assay used here to stain M. xanthus OM material.…”

Section: Resultsmentioning

confidence: 99%

Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments

et al. 2014

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Myxobacteria are social microbes that exhibit complex multicellular behaviors. By use of fluorescent reporters, we show that Myxococcus xanthus isolates produce long narrow filaments that are enclosed by the outer membrane (OM) and contain proteins. We show that these OM tube (OMT) structures are produced at surprisingly high levels when cells are placed in liquid medium or buffer without agitation. OMTs can be long and easily exceed multiple cell lengths. When viewed by transmission electron microscopy, their morphology varies between tubes and chain-like structures. Intermediate-like structures are also found, suggesting that OMTs may transition between these two morphotypes. In support of this, video epifluorescence microscopy found that OMTs in solution dynamically twist and jiggle. On hard surfaces, myxobacteria glide, and upon cell-cell contact, they can efficiently exchange their OM proteins and lipids by a TraAB-dependent mechanism. Although the structure of OMTs hints at a possible role as conduits for exchange, evidence is presented to the contrary. For example, abundant OMT production occurs in traA or traB mutants and when cells are grown in liquid medium, yet transfer cannot occur under these conditions. Thus, genetic and environmental conditions that promote OMT production are incongruent with OM exchange.

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Section: Resultsmentioning

confidence: 99%

Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments

et al. 2014

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“…Multiple bacterial species have been identified to form membrane extensions or chains of vesicles (11,12,14,35). It is not known why vesicles sometimes remain attached to the cell body and become extended tubular structures.…”

Section: Differentially Expressed Genes During Electron Acceptor Limimentioning

confidence: 99%

Regulation of Gene Expression in Shewanella oneidensis MR-1 during Electron Acceptor Limitation and Bacterial Nanowire Formation

Barchinger

Pirbadian

Sambles

et al. 2016

Appl Environ Microbiol

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In limiting oxygen as an electron acceptor, the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 rapidly forms nanowires, extensions of its outer membrane containing the cytochromes MtrC and OmcA needed for extracellular electron transfer. RNA sequencing (RNA-Seq) analysis was employed to determine differential gene expression over time from triplicate chemostat cultures that were limited for oxygen. We identified 465 genes with decreased expression and 677 genes with increased expression. The coordinated increased expression of heme biosynthesis, cytochrome maturation, and transport pathways indicates that S. oneidensis MR-1 increases cytochrome production, including the transcription of genes encoding MtrA, MtrC, and OmcA, and transports these decaheme cytochromes across the cytoplasmic membrane during electron acceptor limitation and nanowire formation. In contrast, the expression of the mtrA and mtrC homologs mtrF and mtrD either remains unaffected or decreases under these conditions. The ompW gene, encoding a small outer membrane porin, has 40-fold higher expression during oxygen limitation, and it is proposed that OmpW plays a role in cation transport to maintain electrical neutrality during electron transfer. The genes encoding the anaerobic respiration regulator cyclic AMP receptor protein (CRP) and the extracytoplasmic function sigma factor RpoE are among the transcription factor genes with increased expression. RpoE might function by signaling the initial response to oxygen limitation. Our results show that RpoE activates transcription from promoters upstream of mtrC and omcA. The transcriptome and mutant analyses of S. oneidensis MR-1 nanowire production are consistent with independent regulatory mechanisms for extending the outer membrane into tubular structures and for ensuring the electron transfer function of the nanowires. IMPORTANCEShewanella oneidensis MR-1 has the capacity to transfer electrons to its external surface using extensions of the outer membrane called bacterial nanowires. These bacterial nanowires link the cell's respiratory chain to external surfaces, including oxidized metals important in bioremediation, and explain why S. oneidensis can be utilized as a component of microbial fuel cells, a form of renewable energy. In this work, we use differential gene expression analysis to focus on which genes function to produce the nanowires and promote extracellular electron transfer during oxygen limitation. Among the genes that are expressed at high levels are those encoding cytochrome proteins necessary for electron transfer. Shewanella coordinates the increased expression of regulators, metabolic pathways, and transport pathways to ensure that cytochromes efficiently transfer electrons along the nanowires.

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“…Additionally, OMVs may provide a survival advantage between competing species by virture of their bacteriocidal activity (27)(28)(29). OMVs also show promise as vaccine antigen platforms, given their composition and physico-chemical properties (30)(31)(32)(33)(34). For example, OMVs of V. cholerae have been shown to induce protective immunity in experimental animals (35)(36)(37)(38)(39)(40)(41).…”

mentioning

confidence: 99%

“…Various approaches have been used to characterize the protein content of OMVs from different human pathogens, including 1-and 2-dimensional electrophoresis (1-DE and 2-DE) (30,32,33) coupled with mass spectrometry (MS) (25,31,34). Liquid chromatography coupled with MS (LC-MS/MS) has also been applied to define proteins associated with OMVs (42) but only in a limited fashion and never fully coupled with systematic genetic analysis for the role of OMV proteins in virulence or bacterial growth and survival.…”

mentioning

confidence: 99%

Proteomic analysis of Vibrio cholerae outer membrane vesicles

Altındiş

Mekalanos

2014

Proc. Natl. Acad. Sci. U.S.A.

143

110

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Outer membrane vesicles (OMVs) produced by Gram-negative bacteria provide an interesting research material for defining cellenvelope proteins without experimental cell disruption. OMVs are also promising immunogenic platforms and may play important roles in bacterial survival and pathogenesis. We used in-solution trypsin digestion coupled to mass spectrometry to identify 90 proteins present in OMVs of Vibrio cholerae when grown under conditions that activate the TCP pilus virulence regulatory protein (ToxT) virulence regulon. The ToxT expression profile and potential contribution to virulence of these proteins were assessed using ToxT and in vivo RNA-seq, Tn-seq, and cholera stool proteomic and other genome-wide data sets. Thirteen OMV-associated proteins appear to be essential for cell growth, and therefore may represent antibacterial drug targets. Another 12 nonessential OMV proteins, including DegP protease, were required for intestinal colonization in rabbits. Comparative proteomics of a degP mutant revealed the importance of DegP in the incorporation of nine proteins into OMVs, including ones involved in biofilm matrix formation and various substrates of the type II secretion system. Taken together, these results suggest that DegP plays an important role in determining the content of OMVs and also affects phenotypes such as intestinal colonization, proper function of the type II secretion system, and formation of biofilm matrix.HtrA family | in-solution digestion | biofilm formation | CTXϕ phage

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Production of Outer Membrane Vesicles and Outer Membrane Tubes by Francisella novicida

Cited by 134 publications

References 77 publications

Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments

Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments

Regulation of Gene Expression in Shewanella oneidensis MR-1 during Electron Acceptor Limitation and Bacterial Nanowire Formation

Proteomic analysis of Vibrio cholerae outer membrane vesicles

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