scholarly journals The novel shapeshifting bacterial phylum Saltatorellota

2019 ◽  
Author(s):  
Sandra Wiegand ◽  
Mareike Jogler ◽  
Timo Kohn ◽  
Ram Prasad Awal ◽  
Sonja Oberbeckmann ◽  
...  
Keyword(s):  
Cell Wall ◽  
Turgor Pressure ◽  
The Novel ◽  
Free Living ◽  
E Coli ◽  
Type Iv ◽  
Peptidoglycan Cell Wall ◽  
Living Bacterium ◽  
Free Living Bacterium ◽  
Shape Changes

AbstractOur current understanding of a free-living bacterium - capable of withstanding a variety of environmental stresses-is represented by the image of a peptidoglycan-armored rigid casket. The making and breaking of peptidoglycan greatly determines cell shape. The cytoplasmic membrane follows this shape, pressed towards the cell wall by turgor pressure. Consequently, bacteria are morphologically static organisms, in contrast to eukaryotic cells that can facilitate shape changes. Here we report the discovery of the novel bacterial phylum Saltatorellota, that challenges this concept of a bacterial cell. Members of this phylum can change their shape, are capable of amoeba-like locomotion and trunk-formation through the creation of extensive pseudopodia-like structures. Two independent Saltatorellota cells can fuse, and they employ various forms of cell division from budding to canonical binary fission. Despite their polymorphisms, members of the Saltatorellota do possess a peptidoglycan cell wall. Their genomes encode flagella and type IV pili as well as a bacterial actin homolog, the ‘saltatorellin’. This protein is most similar to MamK, a dynamic filament-forming protein, that aligns and segregates magnetosome organelles via treadmilling. We found saltatorellin to form filaments in both, E. coli and Magnetospirillum gryphiswaldense, leading to the hypothesis that shapeshifting and pseudopodia formation might be driven by treadmilling of saltatorellin.

scholarly journals Isolation of a New Free-living Bacterium Containing R-bodies

Microbiology ◽  
1986 ◽  
Vol 132 (10) ◽  
pp. 2801-2805 ◽  
Author(s):  
M. C. FUSTE ◽  
M. D. SIMON-PUJOL ◽  
A. M. MARQUES ◽  
J. GUINEA ◽  
F. CONGREGADO
Keyword(s):  
Free Living ◽  
Living Bacterium ◽  
Free Living Bacterium

scholarly journals Direct Measurement of the Relative Contributions of Turgor Pressure, the Peptidoglycan Cell Wall and Cytoskeletal Filaments to Gram-negative Prokaryotic Cell Mechanics using AFM

2009 ◽  
Vol 96 (3) ◽  
pp. 520a
Author(s):  
Mingzhai Sun ◽  
Yi Deng ◽  
Hugo Arellano Santoyo ◽  
Siyuan Wang ◽  
Joshua W. Shaevitz
Keyword(s):  
Cell Wall ◽  
Direct Measurement ◽  
Cell Mechanics ◽  
Turgor Pressure ◽  
Gram Negative ◽  
Prokaryotic Cell ◽  
Peptidoglycan Cell Wall

scholarly journals Longitudinal cell division is associated with single mutations in the FtsZ-recruiting SsgB in Streptomyces

2019 ◽  
Author(s):  
Xiansha Xiao ◽  
Joost Willemse ◽  
Patrick Voskamp ◽  
Xinmeng Li ◽  
Meindert Lamers ◽  
...  
Keyword(s):  
Cell Division ◽  
Biochemical Analysis ◽  
Amino Acid Substitutions ◽  
Free Living ◽  
Division Plane ◽  
Z Ring ◽  
Living Bacterium ◽  
Longitudinal Division ◽  
Longitudinal Cell ◽  
Free Living Bacterium

ABSTRACTIn most bacteria, cell division begins with the polymerization of the GTPase FtsZ at the mid-cell, which recruits the division machinery to initiate cell constriction. In the filamentous bacterium Streptomyces, cell division is positively controlled by SsgB, which recruits FtsZ to the future septum sites and promotes Z-ring formation. Here we show via site-saturated mutagenesis that various amino acid substitutions in the highly conserved SsgB protein result in the production of ectopically placed septa, that sever spores diagonally or along the long axis, perpendicular to the division plane. Ectopic septa were especially prominent when cells expressed SsgB variants with substitutions in residue E120. Biochemical analysis of SsgB variant E120G revealed that its interaction with - and polymerization of - FtsZ had been maintained. The crystal structure of S. coelicolor SsgB was resolved and the position of residue E120 suggests its requirement for maintaining the proper angle of helix α3, thus providing a likely explanation for the aberrant septa formed in SsgB E120 substitution mutants. Taken together, our work presents the first example of longitudinal division in a free living bacterium, which is explained entirely by changes in the FtsZ-recruiting protein SsgB.

scholarly journals Comparative Genomics of Burkholderia singularis sp. nov., a Low G+C Content, Free-Living Bacterium That Defies Taxonomic Dissection of the Genus Burkholderia

2017 ◽  
Vol 8 ◽  
Author(s):  
Peter Vandamme ◽  
Charlotte Peeters ◽  
Birgit De Smet ◽  
Erin P. Price ◽  
Derek S. Sarovich ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Free Living ◽  
Living Bacterium ◽  
Free Living Bacterium

scholarly journals Msh Pilus Mutations Increase the Ability of a Free-Living Bacterium to Colonize a Piscine Host

2020 ◽  
Author(s):  
Jarrett F. Lebov ◽  
Brendan J. M. Bohannan
Keyword(s):  
Dominant Role ◽  
Shewanella Oneidensis ◽  
Loss Of Function ◽  
Surface Adhesion ◽  
Free Living ◽  
Environmental Surfaces ◽  
Evolutionary Changes ◽  
Novel Host ◽  
Living Bacterium ◽  
Free Living Bacterium

Symbioses between animals and bacteria are ubiquitous. To better understand these relationships, it is essential to unravel how bacteria evolve to colonize hosts. Previously, we serially passaged the free-living bacterium, Shewanella oneidensis, through the digestive tracts of germ-free larval zebrafish (Danio rerio) to uncover the evolutionary changes involved in the initiation of a novel symbiosis with a vertebrate host. After 20 passages, we discovered an adaptive missense mutation in the mshL gene of the msh pilus operon, which improved host colonization, increased swimming motility, and reduced surface adhesion. In the present study, we have determined that this mutation was a loss-of-function mutation and found that it improved zebrafish colonization by augmenting S. oneidensis representation in the water column outside larvae through a reduced association with environmental surfaces. Additionally, we found that strains containing the mshL mutation were able to immigrate into host digestive tracts at higher rates per capita. However, mutant and evolved strains exhibited no evidence of a competitive advantage after colonizing hosts. Our results demonstrate that bacterial behaviors outside the host can play a dominant role in facilitating the onset of novel host associations.

scholarly journals Lytic transglycosylases mitigate periplasmic crowding by degrading soluble cell wall turnover products

2021 ◽  
Author(s):  
Anna I Weaver ◽  
Laura Alvarez ◽  
Kelly M Rosch ◽  
Asraa Ahmed ◽  
Garrett S Wang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Critical Role ◽  
Compositional Analysis ◽  
Dynamic Structure ◽  
Lytic Transglycosylases ◽  
E Coli ◽  
Peptidoglycan Synthesis ◽  
Soluble Cell ◽  
Peptidoglycan Cell Wall ◽  
New Material

The peptidoglycan cell wall is a predominant defining structure of bacteria, determining cell shape and supporting survival in diverse conditions. As a single, macromolecular sacculus enveloping the bacterial cell during growth and division, peptidoglycan is necessarily a dynamic structure that requires highly regulated synthesis of new material, remodeling, and turnover, or autolysis, of old material. Despite ubiquitous clinical exploitation of peptidoglycan synthesis as an antibiotic target, much remains unknown about how bacteria modulate synthetic and autolytic processes. Here, we couple bacterial genetics in <em>Vibrio cholerae</em> with compositional analysis of soluble pools of peptidoglycan turnover products to uncover a critical role for a widely misunderstood class of autolytic enzymes, the lytic transglycosylases (LTGs). We demonstrate that LTG activity is specifically required for vegetative growth. The vast majority of LTGs, however, are dispensable for growth, and defects that are ultimately lethal accumulate due to generally inadequate LTG activity, rather than the absence of specific individual enzymes. Consistent with this, we found that a heterologously expressed <em>E. coli</em> LTG, MltE, is capable of sustaining <em>V. cholerae</em> growth in the absence of endogenous LTGs. Lastly, we demonstrate that soluble, uncrosslinked, endopeptidase-dependent peptidoglycan chains accumulate in the WT, and, to a higher degree, in LTG mutants, and that LTG mutants are hyper-susceptible to the production of diverse periplasmic polymers. Collectively, our results suggest that a key function of LTGs is to prevent toxic crowding of the periplasm with synthesis-derived PG fragments. Contrary to prevailing models, our data further suggest that this process can be temporally separate from peptidoglycan synthesis.

Internal Membranes in the Nitrogen Fixing Organisms: Free-Living Azotobacter vinelandii and Rhizobium japonicum Bacteriods

1974 ◽  
Vol 32 ◽  
pp. 172-173
Author(s):  
D. Raveed ◽  
D. W. Reed ◽  
R. E. Toia
Keyword(s):  
Cytoplasmic Membrane ◽  
Azotobacter Vinelandii ◽  
Molecular Nitrogen ◽  
Membrane System ◽  
Rhizobium Japonicum ◽  
Intracellular Membrane ◽  
Free Living ◽  
Cytoplasmic Material ◽  
Living Bacterium ◽  
Free Living Bacterium

The free-living bacterium Azotobacter vinelandii carries out the fixation of molecular nitrogen under aerobic conditions. During growth at high oxygen concentrations, these bacteria exhibit high rates of both respiration and nitrogen fixation. Internal membranes are not easily seen in sections of intact bacteria but an extensive intracellular membrane system is apparent in osmotically-lysed cells (Fig. 1). Equilibration of the cells with 0.3 M glycerol and rapid dilution into ten volumes of 0.01 M Tris-HCl buffer, pH 7.4, permits the escape of electron dense cytoplasmic material. These intracellular membranes which contain the respiratory components of the cell are spherical invaginations of the cytoplasmic membrane and are completely separable from the smaller vesicular azotophore membranes which contain the nitrogenase in A. vinelandii.

scholarly journals The transpeptidase PBP2 governs initial localization and activity of the major cell-wall synthesis machinery in E. coli

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Gizem Özbaykal ◽  
Eva Wollrab ◽  
Francois Simon ◽  
Antoine Vigouroux ◽  
Baptiste Cordier ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Envelope ◽  
Cylindrical Part ◽  
Single Particle Tracking ◽  
Cell Wall Synthesis ◽  
E Coli ◽  
Peptidoglycan Cell Wall ◽  
Direct Binding ◽  
Local Cell ◽  
Residual Correlations

Bacterial shape is physically determined by the peptidoglycan cell wall. The cell-wall-synthesis machinery responsible for rod shape in Escherichia coli is the processive 'Rod complex'. Previously, cytoplasmic MreB filaments were thought to govern formation and localization of Rod complexes based on local cell-envelope curvature. Using single-particle tracking of the transpeptidase and Rod-complex component PBP2, we found that PBP2 binds to a substrate different from MreB. Depletion and localization experiments of other putative Rod-complex components provide evidence that none of those provide the sole rate-limiting substrate for PBP2 binding. Consistently, we found only weak correlations between MreB and envelope curvature in the cylindrical part of cells. Residual correlations do not require curvature-based Rod-complex initiation but can be attributed to persistent rotational motion. We therefore speculate that the local cell-wall architecture provides the cue for Rod-complex initiation, either through direct binding by PBP2 or through an unknown intermediate.

scholarly journals Phenotypic Parallelism during Experimental Adaptation of a Free-Living Bacterium to the Zebrafish Gut

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Jarrett F. Lebov ◽  
Brandon H. Schlomann ◽  
Catherine D. Robinson ◽  
Brendan J. M. Bohannan
Keyword(s):  
Experimental Evolution ◽  
Bacterial Species ◽  
Shewanella Oneidensis ◽  
Free Living ◽  
Content Type ◽  
Larval Zebrafish ◽  
Health And Development ◽  
Living Bacterium ◽  
Animal Hosts ◽  
Free Living Bacterium

ABSTRACT Although animals encounter a plethora of bacterial species throughout their lives, only a subset colonize vertebrate digestive tracts, and these bacteria can profoundly influence the health and development of their animal hosts. However, our understanding of how bacteria initiate symbioses with animal hosts remains underexplored, and this process is central to the assembly and function of gut bacterial communities. Therefore, we used experimental evolution to study a free-living bacterium as it adapts to a novel vertebrate host by serially passaging replicate populations of Shewanella oneidensis through the intestines of larval zebrafish (Danio rerio). After approximately 200 bacterial generations, isolates from evolved populations improved their ability to colonize larval zebrafish during competition against their unpassaged ancestor. Genome sequencing revealed unique sets of mutations in the two evolved isolates exhibiting the highest mean competitive fitness. One isolate exhibited increased swimming motility and decreased biofilm formation compared to the ancestor, and we identified a missense mutation in the mannose-sensitive hemagglutinin pilus operon that is sufficient to increase fitness and reproduce these phenotypes. The second isolate exhibited enhanced swimming motility but unchanged biofilm formation, and here the genetic basis for adaptation is less clear. These parallel enhancements in motility and fitness resemble the behavior of a closely related Shewanella strain previously isolated from larval zebrafish and suggest phenotypic convergence with this isolate. Our results demonstrate that adaptation to the zebrafish gut is complex, with multiple evolutionary pathways capable of improving colonization, but that motility plays an important role during the onset of host association. IMPORTANCE Although animals encounter many bacterial species throughout their lives, only a subset colonize vertebrate digestive tracts, and these bacteria can profoundly influence the health and development of their animal hosts. We used experimental evolution to study a free-living bacterium as it adapts to a novel vertebrate host by serially passaging replicate populations of Shewanella oneidensis through the intestines of larval zebrafish (Danio rerio). Our results demonstrate that adaptation to the zebrafish gut is complex, with multiple evolutionary pathways capable of improving colonization, but that motility plays an important role during the onset of host association.

scholarly journals Vibrio natriegens as a pET-Compatible Expression Host Complementary to Escherichia coli

2021 ◽  
Vol 12 ◽  
Author(s):  
Jiaqi Xu ◽  
Feng Dong ◽  
Meixian Wu ◽  
Rongsheng Tao ◽  
Junjie Yang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Expression ◽  
Recombinant Protein Expression ◽  
Catalytic Efficiency ◽  
Consensus Protocol ◽  
E Coli ◽  
Expression Host ◽  
Terrific Broth Medium ◽  
Living Bacterium ◽  
Free Living Bacterium

Efficient and novel recombinant protein expression systems can further reduce the production cost of enzymes. Vibrio natriegens is the fastest growing free-living bacterium with a doubling time of less than 10 min, which makes it highly attractive as a protein expression host. Here, 196 pET plasmids with different genes of interest (GOIs) were electroporated into the V. natriegens strain VnDX, which carries an integrated T7 RNA polymerase expression cassette. As a result, 65 and 75% of the tested GOIs obtained soluble expression in V. natriegens and Escherichia coli, respectively, 20 GOIs of which showed better expression in the former. Furthermore, we have adapted a consensus “what to try first” protocol for V. natriegens based on Terrific Broth medium. Six sampled GOIs encoding biocatalysts enzymes thus achieved 50–128% higher catalytic efficiency under the optimized expression conditions. Our study demonstrated V. natriegens as a pET-compatible expression host with a spectrum of highly expressed GOIs distinct from E. coli and an easy-to-use consensus protocol, solving the problem that some GOIs cannot be expressed well in E. coli.

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