scholarly journals Sporulation, bacterial cell envelopes, and the origin of life

2016 ◽  
Author(s):  
Elitza I Tocheva ◽  
Davi R Ortega ◽  
Grant J Jensen
Keyword(s):  
Cell Walls ◽  
Cell Envelope ◽  
Early Earth ◽  
Native State ◽  
Intact Cells ◽  
Gram Negative ◽  
The Origin Of Life ◽  
Cell Plan ◽  
Electron Cryotomography ◽  
Cell Envelopes

Four recent papers from our group exploiting the power of electron cryotomography to produce 3-D reconstructions of intact cells in a near-native state have led to the proposal that an ancient sporulation-like event gave rise to the second membrane in diderm bacteria. Here we review the images of sporulating monoderm and diderm cells which show how sporulation leads to diderm cells. We also review the images of Gram-negative and Gram-positive cell walls that show they are more closely related than previously thought, and explain how this provides critical support for the hypothesis. Mapping the distribution of cell envelope architectures onto the most recent phylogenetic tree of life then leads to the conclusion that the diderm cell plan, and therefore the sporulation-like event that gave rise to it, must be very ancient. One explanation for the biogeologic record is that during the cataclysmic transitions of early Earth, cellular evolution may have gone through a bottleneck where only spores survived (LUCA was a spore).

scholarly journals Molecular architecture of theLegionellaDot/Icm type IV secretion system

2018 ◽  
Author(s):  
Debnath Ghosal ◽  
Yi-Wei Chang ◽  
Kwang Cheol Jeong ◽  
Joseph P. Vogel ◽  
Grant J. Jensen
Keyword(s):  
Legionella Pneumophila ◽  
Cell Envelope ◽  
Secretion System ◽  
Host Cells ◽  
Molecular Architecture ◽  
Intact Cells ◽  
Type Iv ◽  
Type Ivb Secretion ◽  
Electron Cryotomography ◽  
First Time

AbstractLegionella pneumophilasurvives and replicates inside host cells by secreting ~300 effectors through the Dot/Icm type IVB secretion system (T4BSS). Understanding this machine’s structure is challenging because of its large number of components (27) and integration into all layers of the cell envelope. Previously we overcame this obstacle by imaging the Dot/Icm T4BSS in its native state within intact cells through electron cryotomography. Here we extend our observations by imaging a stabilized mutant that yielded a higher resolution map. We describe for the first time the presence of a well-ordered central channel that opens up into a windowed large (~32 nm wide) secretion chamber with an unusual 13-fold symmetry. We then dissect the complex by matching proteins to densities for many components, including all those with periplasmic domains. The placement of known and predicted structures of individual proteins into the map reveals the architecture of the T4BSS and provides a roadmap for further investigation of this amazing specialized secretion system.

scholarly journals Global and Targeted Lipid Analysis ofGemmata obscuriglobusReveals the Presence of Lipopolysaccharide, a Signature of the Classical Gram-Negative Outer Membrane

2015 ◽  
Vol 198 (2) ◽  
pp. 221-236 ◽  
Author(s):  
Rajendra Mahat ◽  
Corrine Seebart ◽  
Franco Basile ◽  
Naomi L. Ward
Keyword(s):  
Outer Membrane ◽  
Lipid A ◽  
Direct Evidence ◽  
Cell Envelope ◽  
Bacterial Species ◽  
Gas Chromatography Mass Spectrometry ◽  
Differential Staining ◽  
Gram Negative ◽  
Negative Cell ◽  
Cell Plan

ABSTRACTPlanctomycete bacteria possess many unusual cellular properties, contributing to a cell plan long considered to be unique among the bacteria. However, data from recent studies are more consistent with a modified Gram-negative cell plan. A key feature of the Gram-negative plan is the presence of an outer membrane (OM), for which lipopolysaccharide (LPS) is a signature molecule. Despite genomic evidence for an OM in planctomycetes, no biochemical verification has been reported. We attempted to detect and characterize LPS in the planctomyceteGemmata obscuriglobus. We obtained direct evidence for LPS and lipid A using electrophoresis and differential staining. Gas chromatography-mass spectrometry (GC-MS) compositional analysis of LPS extracts identified eight different 3-hydroxy fatty acids (3-HOFAs), 2-keto 3-deoxy-d-manno-octulosonic acid (Kdo), glucosamine, and hexose and heptose sugars, a chemical profile unique to Gram-negative LPS. Combined with molecular/structural information collected from matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) MS analysis of putative intact lipid A, these data led us to propose a heterogeneous hexa-acylated lipid A structure (multiple-lipid A species). We also confirmed previous reports ofG. obscuriglobuswhole-cell fatty acid (FA) and sterol compositions and detected a novel polyunsaturated FA (PUFA). Our confirmation of LPS, and by implication an OM, inG. obscuriglobusraises the possibility that other planctomycetes possess an OM. The pursuit of this question, together with studies of the structural connections between planctomycete LPS and peptidoglycans, will shed more light on what appears to be a planctomycete variation on the Gram-negative cell plan.IMPORTANCEBacterial species are classified as Gram positive or negative based on their cell envelope structure. For 25 years, the envelope of planctomycete bacteria has been considered a unique exception, as it lacks peptidoglycan and an outer membrane (OM). However, the very recent detection of peptidoglycan in planctomycete species has provided evidence for a more conventional cell wall and raised questions about other elements of the cell envelope. Here, we report direct evidence of lipopolysaccharide in the planctomyceteG. obscuriglobus, suggesting the presence of an OM and supporting the proposal that the planctomycete cell envelope is an extension of the canonical Gram-negative plan. This interpretation features a convoluted cytoplasmic membrane and expanded periplasmic space, the functions of which provide an intriguing avenue for future investigation.

Isolierung und Eigenschaften der Zellhiille der Griinalge Chlorella fusca / Isolation and Properties of the Cell Envelope of the Green Alga Chlorella fusca

1975 ◽  
Vol 30 (9-10) ◽  
pp. 684-686
Author(s):  
W. Hülsen ◽  
D. Kubin
Keyword(s):  
Cell Envelope ◽  
Morphological Structure ◽  
Chlorella Cell ◽  
High Concentration ◽  
Chlorella Fusca ◽  
Intact Cells ◽  
Mechanical Procedure ◽  
Green Alga Chlorella ◽  
Hexose Uptake ◽  
Cell Envelopes

Chlorella cell envelopes were isolated by a mechanical procedure. The obtained morphological structure shown in an EM-picture has a mean density of ρ = 1.42. A characteristic chemical property of the envelope is the percentage of mono-and di-unsaturated C18-fatty acids which is considerably higher than that of intact cells. With 14C labelled sugars a selectivity of the hexose uptake could be shown, galactose uptake amounting only to about one fifth that of glucose and mannose. The uptake shows a temperature maximum. Part of the 14C registered after a 30 min uptake peroid is released by high concentration of unlabelled glucose, 20% are irreversibly fixed.

Cell envelope analysis of Coxiella Burneti phase I and phase II

1974 ◽  
Vol 20 (10) ◽  
pp. 1465-1470 ◽  
Author(s):  
T. R. Jerrells ◽  
David J. Hinrichs ◽  
L. P. Mallavia
Keyword(s):  
Electron Microscopy ◽  
Phase I ◽  
Phase Ii ◽  
Cell Envelope ◽  
Diaminopimelic Acid ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Carbohydrate Concentration ◽  
Morphological Studies ◽  
Cell Envelopes

Cell envelopes of Coxiella burneti, Nine Mile, phase I and phase II were examined by electron microscopy and analyzed chemically in an attempt to characterize the phase phenomenon noted in this organism. Electron microscopy of intact organisms as well as cell envelope fractions revealed a morphology similar to many gram-negative bacteria and other rickettsiae. Morphological studies revealed no differences between C. burneti in phase I or II. Chemical analyses revealed a basic composition similar to that reported for members of the genus Rickettsia and many gram-negative bacteria. Cell envelopes of both phase types of this organism (I and II) contained similar amounts of extractable lipid, similar amino acid composition, and the amino sugars glucosamine and muramic acid. Diaminopimelic acid (DAP) was demonstrated in the cell envelope of both phase types. Coxiella burneti phase I differed from the phase II form in carbohydrate composition as well as protein and carbohydrate concentration. Glucuronic acid, glucose, and galactose were found in C. burneti phase I envelopes, whereas only glucose and galactose were present in phase II envelopes.

Fine Structure and Radiation Resistance in Acinetobacter: Studies on a Resistant Strain

1968 ◽  
Vol 3 (2) ◽  
pp. 273-294
Author(s):  
MARGARET J. THORNLEY ◽  
AUDREY M. GLAUERT
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
Radiation Resistance ◽  
Cell Walls ◽  
Proteolytic Enzymes ◽  
Gram Negative Bacteria ◽  
Intact Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Isolated Cell

An electron-microscope study of thin sections and negatively stained preparations of intact cells and isolated cell walls of a bacterium which is moderately resistant to ionizing radiation, Acinetobacter strain 199A, showed that it is similar to other Gram-negative bacteria except for its mode of division and for the fine structure of some of the surface layers. During division the cells form a fairly thick septum similar to those observed in Gram-positive bacteria. An examination of the appearance and chemical composition of isolated cell walls before and after treatment with enzymes, detergents and lipid solvents revealed that three layers, each with a characteristic fine structure, are present in the cell wall: (1) an outer membrane with an array of peg-like subunits; (2) a layer of wrinkled material which is digested by proteolytic enzymes; and (3) a smooth, rigid layer, which contains the mucopeptide components of the cell wall. These observations are compared with the results of other workers for various Gram-negative bacteria. From comparisons with the structure of more radiation-sensitive strains of Acinetobacter, it appears that layer (2) may be associated with the radiation resistance of the organism.

Cation content and cation-exchange capacity of intact cells and cell envelopes of viomycin-sensitive and -resistant strains of Rhizobium meliloti

1971 ◽  
Vol 17 (10) ◽  
pp. 1283-1286 ◽  
Author(s):  
K. K.-Y. Yu ◽  
D. C. Jordan
Keyword(s):  
Cation Exchange ◽  
Mutant Strain ◽  
Cation Exchange Capacity ◽  
Rhizobium Meliloti ◽  
Cell Envelope ◽  
Resistant Mutant ◽  
Exchange Capacity ◽  
Intact Cells ◽  
Cell Envelopes ◽  
Resistant Cells

The envelope (wall plus plasma membrane) of a viomycin-resistant mutant of Rhizobium meliloti exhibited a higher calcium concentration than that of the viomycin-sensitive parent strain. However, the cation exchange capacity of the sensitive cells was almost twice that of the resistant cells, indicating that the excess calcium in the resistant cells is not available for exchange with external cations. Since externally supplied cations can block viomycin uptake by sensitive cells it is suggested that viomycin penetration in such cells involves an initial attraction of the basic antibiotic molecules to negatively charged sites in the envelope. Viomycin resistance in the mutant strain appears to be the result of (a) a decrease in the number of negatively charged sites and (b) the association with these sites, via calcium-bridging, of previously discovered envelope phospholipids capable of complexing with the drug.Chelators decreased viomycin resistance in the mutant strain, presumably by removal or destruction of the barrier in the cell envelope involved in decreased drug penetration. The decrease in viomycin resistance caused by cold shock was accompanied by a release of envelope phospholipid without a concurrent release of Ca2+.

scholarly journals In Situ Characterization of Differences in the Viscoelastic Response of Individual Gram-Negative and Gram-Positive Bacterial Cells

2009 ◽  
Vol 191 (17) ◽  
pp. 5518-5525 ◽  
Author(s):  
Virginia Vadillo-Rodriguez ◽  
Sarah R. Schooling ◽  
John R. Dutcher
Keyword(s):  
Viscoelastic Properties ◽  
Cell Envelope ◽  
Outer Membrane Proteins ◽  
Elastic Response ◽  
Bacterial Cells ◽  
Structure Property ◽  
Gram Positive ◽  
Gram Negative ◽  
Structure Property Relationships ◽  
Cell Envelopes

ABSTRACT We used a novel atomic force microscopy (AFM)-based technique to compare the local viscoelastic properties of individual gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacterial cells. We found that the viscoelastic properties of the bacterial cells are well described by a three-component mechanical model that combines an instantaneous elastic response and a delayed elastic response. These experiments have allowed us to investigate the relationship between the viscoelastic properties and the structure and composition of the cell envelope. In addition, this is the first report in which the mechanical role of Lpp, the major peptidoglycan-associated lipoprotein and one of the most abundant outer membrane proteins in E. coli cells, has been quantified. We expect that our findings will be helpful in increasing the understanding of the structure-property relationships of bacterial cell envelopes.

scholarly journals Formation of Thiophene under Simulated Volcanic Hydrothermal Conditions on Earth—Implications for Early Life on Extraterrestrial Planets?

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 149
Author(s):  
Thomas Geisberger ◽  
Jessica Sobotta ◽  
Wolfgang Eisenreich ◽  
Claudia Huber
Keyword(s):  
Fatty Acids ◽  
Hydrogen Sulfide ◽  
Early Life ◽  
Organic Molecules ◽  
Metal Sulfides ◽  
Early Earth ◽  
Hydrothermal Conditions ◽  
Evolution Of Metabolism ◽  
Thiophene Derivatives ◽  
The Origin Of Life

Thiophene was detected on Mars during the Curiosity mission in 2018. The compound was even suggested as a biomarker due to its possible origin from diagenesis or pyrolysis of biological material. In the laboratory, thiophene can be synthesized at 400 °C by reacting acetylene and hydrogen sulfide on alumina. We here show that thiophene and thiophene derivatives are also formed abiotically from acetylene and transition metal sulfides such as NiS, CoS and FeS under simulated volcanic, hydrothermal conditions on Early Earth. Exactly the same conditions were reported earlier to have yielded a plethora of organic molecules including fatty acids and other components of extant metabolism. It is therefore tempting to suggest that thiophenes from abiotic formation could indicate sites and conditions well-suited for the evolution of metabolism and potentially for the origin-of-life on extraterrestrial planets.

scholarly journals FINE STRUCTURE OF THE GRAM-NEGATIVE BACTERIUM ACETOBACTER SUBOXYDANS

1964 ◽  
Vol 20 (2) ◽  
pp. 217-233 ◽  
Author(s):  
G. W. Claus ◽  
L. E. Roth
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Walls ◽  
Negative Staining ◽  
Homogeneous Layer ◽  
Physical Treatment ◽  
Thin Sections ◽  
Gram Negative ◽  
Acetobacter Suboxydans ◽  
Negative Cell

The morphological features of the cell wall, plasma membrane, protoplasmic constituents, and flagella of Acetobacter suboxydans (ATCC 621) were studied by thin sectioning and negative staining. Thin sections of the cell wall demonstrate an outer membrane and an inner, more homogeneous layer. These observations are consistent with those of isolated, gram-negative cell-wall ghosts and the chemical analyses of gram-negative cell walls. Certain functional attributes of the cell-wall inner layer and the structural comparisons of gram-negative and gram-positive cell walls are considered. The plasma membrane is similar in appearance to the membrane of the cell wall and is occasionally found to be folded into the cytoplasm. Certain features of the protoplasm are described and discussed, including the diffuse states of the chromatinic material that appear to be correlated with the length of the cell and a polar differentiation in the area of expected flagellar attachment. Although the flagella appear hollow in thin sections, negative staining of isolated flagella does not substantiate this finding. Severe physical treatment occasionally produces a localized penetration into the central region of the flagellum, the diameter of which is much smaller then that expected from sections. A possible explanation of this apparent discrepancy is discussed.

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