Outer membrane vesiculation of acinetobacter calcoaceticus

1990 ◽  
Vol 10 (2) ◽  
pp. 117-123 ◽  
Author(s):  
P. Borneleit ◽  
H.-P. Kleber ◽  
H. Binder
Keyword(s):  
Outer Membrane ◽  
Acinetobacter Calcoaceticus ◽  
Membrane Vesiculation

Effect of Hexadecane-induced Vesiculation on the Outer Membrane of Acinetobacter calcoaceticus

Microbiology ◽  
1988 ◽  
Vol 134 (7) ◽  
pp. 1983-1992 ◽  
Author(s):  
P. Borneleit ◽  
T. Hermsdorf ◽  
R. Claus ◽  
P. Walther ◽  
H.-P. Kleber
Keyword(s):  
Outer Membrane ◽  
Acinetobacter Calcoaceticus

scholarly journals Outer Membrane Vesiculation Facilitates Surface Exchange and In Vivo Adaptation of Vibrio cholerae

2020 ◽  
Vol 27 (2) ◽  
pp. 225-237.e8 ◽  
Author(s):  
Franz G. Zingl ◽  
Paul Kohl ◽  
Fatih Cakar ◽  
Deborah R. Leitner ◽  
Fabian Mitterer ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Vibrio Cholerae ◽  
Surface Exchange ◽  
Membrane Vesiculation

scholarly journals Microevolution in the major outer membrane protein OmpA of Acinetobacter baumannii

2019 ◽  
Author(s):  
Alejandro M. Viale ◽  
Benjamin A. Evans
Keyword(s):  
Acinetobacter Baumannii ◽  
Host Cell ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Vaccine Design ◽  
Acinetobacter Calcoaceticus ◽  
Relevant Information ◽  
Cell Recognition ◽  
The Many ◽  
Host Cell Recognition

AbstractAcinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host cell recognition, biofilm formation, regulation of OM stability, permeability, and antibiotic resistance. OmpA members are two-domain proteins with an N-terminal eight-stranded β-barrel domain with four external loops (ELs) interacting with the environment, and a C-terminal periplasmic domain binding non-covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic, and multilocus sequence analyses from 242 strains of the Acinetobacter calcoaceticus/Acinetobacter baumannii complex (ACB), 222 from A. baumannii, to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) comprising 50 different alleles coding for 29 different proteins. Polymorphisms were concentrated in 5 regions corresponding to the four ELs and the C-terminal end, and provided evidence for different intra-genic recombination events. ompA variants were not randomly distributed across the A. baumannii phylogeny, with the most frequent V1a1 allele almost exclusive to clonal complex 1 (CC1) strains and the second most frequent V2a1 allele found in the majority of CC2 strains. Evidence was found for assortative exchanges of ompA alleles not only between different A. baumannii clonal lineages, but also different ACB species. Within A. baumannii ompA non-synonymous substitutions were concentrated in the ELs regions, but were more abundant in the transmembrane regions between different Acinetobacter species. The overall results have implications for A. baumannii evolution, epidemiology, virulence, and vaccine design.ImportanceAcinetobacter baumannii is an increasing MDR threat in nosocomial settings associated with prolonged hospitalization and concomitantly increased healthcare costs. The main A. baumannii OM protein, OmpA, is a multifaceted two-domain protein implicated in host cell recognition and adhesion, cytotoxicity, biofilm formation, and as a slow porin for antibiotics and small hydrophilic nutrients. A. baumannii OmpA has been proposed as a potential target for anti-virulence drugs and as a vaccine candidate. Given the many interactions of this protein with environmental factors including host defenses, it is certainly subjected to many selective pressures. Here, we analyzed the microevolution of this OM protein in the A. baumannii population to obtain clues on the extent to which selection in the clinical setting has shaped this protein. The results provide relevant information on the main causes driving evolution of this protein, with potential implications in A. baumannii epidemiology, virulence, and vaccine design.

scholarly journals Microevolution in the major outer membrane protein OmpA of Acinetobacter baumannii

2020 ◽  
Vol 6 (6) ◽  
Author(s):  
Alejandro M. Viale ◽  
Benjamin A. Evans
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Type Species ◽  
Acinetobacter Calcoaceticus ◽  
Content Type ◽  
Link Type ◽  
Periplasmic Domain ◽  
Host Cell Recognition ◽  
Combined Data

Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two‐domain proteins with an N‐terminal eight‐stranded β‐barrel domain with four external loops (ELs) interacting with the environment, and a C‐terminal periplasmic domain binding non‐covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus / Acinetobacter baumannii complex (ACB), 946 from A. baumannii , to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii , encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C‐terminal end, and provided evidence for intra‐genic recombination. ompA variants were not randomly distributed across the A . baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A . baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.

Adaptive synthesis of a rough lipopolysaccharide in Geobacter sulfurreducens for metal reduction and detoxification

2021 ◽  
Author(s):  
Morgen M. Clark ◽  
Michael D. Paxhia ◽  
Jenna M. Young ◽  
Michael P. Manzella ◽  
Gemma Reguera
Keyword(s):  
Outer Membrane ◽  
Cell Envelope ◽  
Biological Significance ◽  
Geobacter Sulfurreducens ◽  
Metal Reduction ◽  
Permeability Barrier ◽  
O Antigen ◽  
Membrane Vesiculation ◽  
Reducing Bacteria ◽  
Metal Reducing Bacteria

The ability of some metal-reducing bacteria to produce a rough (no O-antigen) lipopolysaccharide (LPS) could facilitate surface interactions with minerals and metal reduction. Consistent with this, the laboratory model metal reducer Geobacter sulfurreducens PCA produced two rough LPS isoforms (with or without a terminal methyl-quinovosamine sugar) when growing with the soluble electron acceptor, fumarate, but only expressed the shorter and more hydrophilic variant when reducing iron oxides. We reconstructed from genomic data conserved pathways for the synthesis of the rough LPS and generated heptosyltransferase mutants with partial (Δ rfaQ ) and complete (Δ rfaC ) truncations in the core oligosaccharide. The stepwise removal of the LPS core sugars reduced the hydrophilicity of the cell and increased outer membrane vesiculation. These changes in outer membrane charge and remodeling did not substantially impact planktonic growth but disrupted the developmental stages and structure of electroactive biofilms. Furthermore, the mutants assembled conductive pili for the extracellular mineralization of the toxic uranyl cation, yet were unable to prevent the permeation and mineralization of the radionuclide in the cell envelope. Hence, not only does the rough LPS promote cell-cell and cell-mineral interactions critical to biofilm formation and metal respiration, but it also functions as a permeability barrier to toxic metal cations. In doing so, the rough LPS maximizes the extracellular reduction of soluble and insoluble metals and preserves cell envelope functions critical to the environmental survival of Geobacter bacteria in metal rich environments and their performance in bioremediation and bioenergy applications. Importance Some metal-reducing bacteria produce a lipopolysaccharide (LPS) without the repeating sugars (O-antigen) that decorate the surface of most Gram-negative bacteria, but the biological significance of this adaptive feature has never been investigated. Using the model representative Geobacter sulfurreducens strain PCA and mutants carrying stepwise truncations in the LPS core sugars, we demonstrate the importance of the rough LPS in the control of cell surface chemistry during the respiration of iron minerals and the formation of electroactive biofilms. Importantly, we describe hitherto overlooked roles for the rough LPS in metal sequestration and outer membrane vesiculation that are critical for the extracellular reduction and detoxification of toxic metals and radionuclides. These results are of interest for the optimization of bioremediation schemes and electricity-harvesting platforms using these bacteria.

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