scholarly journals Peptidoglycan Salvage Enables the Periodontal Pathogen Tannerella forsythia to Survive within the Oral Microbial Community

2021 ◽  
pp. 1-12
Author(s):  
Isabel Hottmann ◽  
Marina Borisova ◽  
Christina Schäffer ◽  
Christoph Mayer
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Tooth Loss ◽  
De Novo ◽  
Periodontal Pathogen ◽  
Tannerella Forsythia ◽  
Gram Negative ◽  
Salvage Pathways ◽  
Axenic Growth ◽  
Nutrition Source

<i>Tannerella forsythia</i> is an anaerobic, fusiform Gram-negative oral pathogen strongly associated with periodontitis, a multibacterial inflammatory disease that leads to the destruction of the teeth-supporting tissue, ultimately causing tooth loss. To survive in the oral habitat, <i>T. forsythia</i> depends on cohabiting bacteria for the provision of nutrients. For axenic growth under laboratory conditions, it specifically relies on the external supply of <i>N</i>-acetylmuramic acid (MurNAc), which is an essential constituent of the peptidoglycan (PGN) of bacterial cell walls. <i>T. forsythia</i> comprises a typical Gram-negative PGN; however, as evidenced by genome sequence analysis, the organism lacks common enzymes required for the <i>de novo</i> synthesis of precursors of PGN, which rationalizes its MurNAc auxotrophy. Only recently insights were obtained into how <i>T. forsythia</i> gains access to MurNAc in its oral habitat, enabling synthesis of the own PGN cell wall. This report summarizes <i>T. forsythia</i>’s strategies to survive in the oral habitat by means of PGN salvage pathways, including recovery of exogenous MurNAc and PGN-derived fragments but also polymeric PGN, which are all derived from cohabiting bacteria either via cell wall turnover or decay of cells. Salvage of polymeric PGN presumably requires the removal of peptides from PGN by an unknown amidase, concomitantly with the translocation of the polymer across the outer membrane. Two recently identified exo-lytic <i>N</i>-acetylmuramidases (Tf_NamZ1 and Tf_NamZ2) specifically cleave the peptide-free, exogenous (nutrition source) PGN in the periplasm and release the MurNAc and disaccharide substrates for the transporters Tf_MurT and Tf_AmpG, respectively, whereas the peptide-containing, endogenous (the self-cell wall) PGN stays unattached. This review also outlines how <i>T. forsythia</i> synthesises the PGN precursors UDP-MurNAc and UDP-<i>N</i>-acetylglucosamine (UDP-GlcNAc), involving homologs of the <i>Pseudomonas</i> sp. recycling enzymes AmgK/MurU and a monofunctional uridylyl transferase (named Tf_GlmU*), respectively.

scholarly journals Identification of a NovelN-Acetylmuramic Acid Transporter in Tannerella forsythia

2016 ◽  
Vol 198 (22) ◽  
pp. 3119-3125 ◽  
Author(s):  
Angela Ruscitto ◽  
Isabel Hottmann ◽  
Graham P. Stafford ◽  
Christina Schäffer ◽  
Christoph Mayer ◽  
...  
Keyword(s):  
De Novo ◽  
Amino Sugar ◽  
Periodontal Pathogen ◽  
Tannerella Forsythia ◽  
Inner Membrane ◽  
Gram Negative ◽  
Content Type ◽  
Sugar Transporters ◽  
E Coli ◽  
Genes Encoding

ABSTRACTTannerella forsythiais a Gram-negative periodontal pathogen lacking the ability to undergode novosynthesis of amino sugarsN-acetylmuramic acid (MurNAc) andN-acetylglucosamine (GlcNAc) that form the disaccharide repeating unit of the peptidoglycan backbone.T. forsythiarelies on the uptake of these sugars from the environment, which is so far unexplored. Here, we identified a novel transporter system ofT. forsythiainvolved in the uptake of MurNAc across the inner membrane and characterized a homolog of theEscherichia coliMurQ etherase involved in the conversion of MurNAc-6-phosphate (MurNAc-6-P) to GlcNAc-6-P. The genes encoding these components were identified on a three-gene cluster spanning Tanf_08375 to Tanf_08385 located downstream from a putative peptidoglycan recycling locus. We show that the three genes, Tanf_08375, Tanf_08380, and Tanf_08385, encoding a MurNAc transporter, a putative sugar kinase, and a MurQ etherase, respectively, are transcriptionally linked. Complementation of the Tanf_08375 and Tanf_08380 genes together intrans, but not individually, rescued the inability of anE. colimutant deficient in the phosphotransferase (PTS) system-dependent MurNAc transporter MurP as well as that of a double mutant deficient in MurP and components of the PTS system to grow on MurNAc. In addition, complementation with this two-gene construct inE. colicaused depletion of MurNAc in the medium, further confirming this observation. Our results show that the products of Tanf_08375 and Tanf_08380 constitute a novel non-PTS MurNAc transporter system that seems to be widespread among bacteria of theBacteroidetesphylum. To the best of our knowledge, this is the first identification of a PTS-independent MurNAc transporter in bacteria.IMPORTANCEIn this study, we report the identification of a novel transporter for peptidoglycan amino sugarN-acetylmuramic acid (MurNAc) in the periodontal pathogenT. forsythia. It has been known since the late 1980s thatT. forsythiais a MurNAc auxotroph relying on environmental sources for this essential sugar. Most sugar transporters, and the MurNAc transporter MurP in particular, require a PTS phosphorelay to drive the uptake and concurrent phosphorylation of the sugar through the inner membrane in Gram-negative bacteria. Our study uncovered a novel type of PTS-independent MurNAc transporter, and although so far, it seems to be unique toT. forsythia, it may be present in a range of bacteria both of the oral cavity and gut, especially of the phylumBacteroidetes.

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.

scholarly journals The extraction of cell walls of Pseudomonas aeruginosa with aqueous phenol. The insoluble residue and material from the aqueous layers

1967 ◽  
Vol 105 (2) ◽  
pp. 759-765 ◽  
Author(s):  
K. Clarke ◽  
G. W. Gray ◽  
D. A. Reaveley
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Cell Walls ◽  
Lipid A ◽  
Diaminopimelic Acid ◽  
Insoluble Residue ◽  
Muramic Acid ◽  
Gram Negative ◽  
Gram Negative Organisms ◽  
Residue Fraction

1. The insoluble residue and material present in the aqueous layers resulting from treatment of cell walls of Pseudomonas aeruginosa with aqueous phenol were examined. 2. The products (fractions AqI and AqII) isolated from the aqueous layers from the first and second extractions respectively account for approx. 25% and 12% of the cell wall and consist of both lipopolysaccharide and muropeptide. 3. The lipid part of the lipopolysaccharide is qualitatively similar to the corresponding material (lipid A) from other Gram-negative organisms, as is the polysaccharide part. 4. The insoluble residue (fraction R) contains sacculi, which also occur in fraction AqII. On hydrolysis, the sacculi yield glucosamine, muramic acid, alanine, glutamic acid and 2,6-diaminopimelic acid, together with small amounts of lysine, and they are therefore similar to the murein sacculi of other Gram-negative organisms. Fraction R also contains substantial amounts of protein, which differs from that obtained from the phenol layer. 5. The possible association or aggregation of lipopolysaccharide, murein and murein sacculi is discussed.

LYSOZYME SENSITIVITY OF THE CELL WALL OF PSEUDO-MONAS AERUGINOSA: FURTHER EVIDENCE FOR THE ROLE OF THE NON-PEPTIDOGLYCAN COMPONENTS IN CELL WALL RIGIDITY

1966 ◽  
Vol 12 (1) ◽  
pp. 105-108 ◽  
Author(s):  
K. Jane Carson ◽  
R. G. Eagon
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Gram Negative Bacteria ◽  
Normal Cells ◽  
Thin Sections ◽  
Gram Negative ◽  
Cell Wall Rigidity

Electron micrographs of thin sections of normal cells of Pseudomonas aeruginosa showed the cell walls to be convoluted and to be composed of two distinct layers. Electron micrographs of thin sections of lysozyme-treated cells of P. aeruginosa showed (a) that the cell walls lost much of their convoluted nature; (b) that the layers of the cell walls became diffuse and less distinct; and (c) that the cell walls became separated from the protoplasts over extensive cellular areas. These results suggest that the peptidoglycan component of the unaltered cell walls of P. aeruginosa is sensitive to lysozyme. Furthermore, it appears that the peptidoglycan component is not solely responsible for the rigidity of the cell walls of Gram-negative bacteria.

The effects of phospholipid depletion on the cleavage pattern of the cell walls of frozen Gram-negative bacteria

1973 ◽  
Vol 19 (8) ◽  
pp. 1056-1057 ◽  
Author(s):  
A. Forge ◽  
J. W. Costerton
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Gram Negative Bacteria ◽  
Cleavage Pattern ◽  
Gram Negative ◽  
Whole Cells ◽  
The Cross ◽  
Double Track ◽  
Chloroform Methanol

Extraction of whole cells of the marine pseudomonad (B-16) with chloroform–methanol causes the disappearance of the cleavage planes, and the cross-sectioned profile of both the cytoplasmic membrane and the double-track layer of the cell wall.

Electron Microscopic Observations on the Effects of Polymixin B Sulfate to Cell Walls of Chlamydia Organisms

1972 ◽  
Vol 30 ◽  
pp. 326-327
Author(s):  
Akira Matsumoto
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Present Report ◽  
Bactericidal Effect ◽  
Chlamydia Psittaci ◽  
Gram Negative Bacteria ◽  
Electron Microscopic ◽  
Cell Content ◽  
Gram Negative ◽  
Reticulate Body

Cell walls of the both types of bodies, mature elementary body(EB) and developmental reticulate body(RB) of Chlamydia psittaci appear the triple layered membrane in thin section. However, in the preparations shadowcast or stained negatively EB cell wall shows hexagonally arrayed structure composed of subunits, 180A in diameter on the inside surface, whereas RB cell wall does not have this structure. Chemical analysis demonstrated that EB cell wall contained a similar amino acid composition with the cell walls of gram-negative bacteria, such as E.coli. The bactericidal effect of polymixin group against gram-negative bacilli is understood that the drug affects to the cell wall and destroys its osmotic regulation. Electron microscopy on the effects of the drug against the gram-negative bacteria revealed the formation of numerous number of projections on the cell wall surface and leakage of cell content through the projections. The present report is concerned with further studies on the fine structure of EB cell walls based on the observation on their response to polymixin B sulfate.

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.

Keeping DNA Out, Letting It In

2019 ◽  
pp. 183-196
Author(s):  
Janet R. Gilsdorf
Keyword(s):  
Genetic Diversity ◽  
Cell Wall ◽  
Haemophilus Influenzae ◽  
Clinical Management ◽  
Cell Walls ◽  
Dna Uptake ◽  
Molecular Tools ◽  
Gram Negative ◽  
Challenging Environment ◽  
Basic Biology

All three meningitis bacteria (meningococci, Haemophilus influenzae, and pneumococci) are able to soak up DNA from their environments; thus, they all exhibit substantial genetic diversity. Those whose cell walls stain Gram negative (meningococci and H. influenzae) use DNA uptake signal sequences to take up the DNA, while pneumococci, which stain Gram positive and thus possess a different kind of cell wall, use a unique and less well understood mechanism. Although these interesting and important scientific discoveries have little to do with the clinical management of meningitis, they reveal a lot about the basic biology of H. influenzae and other meningitis-causing bacteria. By using the molecular tools that permit bacteria to acquire new DNA from their environments, H. influenzae bacteria are able to refashion themselves. In this way, at least a few of the bacteria in the enormous population of bacteria that live in humans are able to cope with whatever challenging environment they happen to fall into, including their transit from the throat, where they normally live, to the blood and meninges, where they cause meningitis.

scholarly journals Cell wall integrity signaling regulates cell wall regeneration via transcriptional activation in Chlamydomonas reinhardtii

2019 ◽  
Author(s):  
Evan Cronmiller ◽  
Deepak Toor ◽  
Nai Chun Shao ◽  
Thamali Kariyawasam ◽  
Ming Hsiu Wang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcriptional Activation ◽  
Cell Walls ◽  
De Novo ◽  
Intact Cell ◽  
Gene Activation ◽  
Cell Wall Integrity ◽  
Luciferase Reporter ◽  
Mrna Accumulation ◽  
Signaling Mechanisms

AbstractAn intact cell wall is critical for protecting the cell from osmotic challenges and harmful environments. Signaling mechanisms are necessary to monitor cell wall integrity and to regulate cell wall production and remodeling during growth and division cycles. The green alga, Chlamydomonas, has a proteinaceous cell wall of defined structure that is readily removed by gametolysin (g-lysin), a metalloprotease released during sexual mating. Naked cells treated with g-lysin induce the mRNA accumulation of > 100 cell wall-related genes within an hour, offering a system to study signaling and regulatory mechanisms for de novo cell wall assembly. Combining quantitative RT-PCR and luciferase reporter assays to probe transcript accumulation and promoter activity, we revealed that up to 500-fold upregulation of cell wall-related genes was driven at least partly by transcriptional activation upon g-lysin treatment. To investigate how naked cells trigger this rapid transcriptional activation, we tested whether osmotic stress and cell wall integrity are involved in this process. Under a constant hypotonic condition, comparable levels of cell wall-gene activation were observed by g-lysin treatment. In contrast, cells in an iso- or hypertonic condition showed up to 80% reduction in the g-lysin-induced gene activation, suggesting that hypotonic conditions are required for full-scale responses to g-lysin treatment. To test whether mechanical perturbation is involved, we isolated and examined a new set of cell wall mutants with defective or little cell walls. All cell wall mutants examined showed a constitutive upregulation of cell wall-related genes at the level, which would only be achieved by the g-lysin treatment in wild-type cells. Our study suggests a signaling that monitors mechanical defects of cell walls and regulates cell wall-gene expression in Chlamydomonas, which may relate to cell wall integrity signaling mechanisms in plants.

scholarly journals The N-Acetylmuramic Acid 6-Phosphate Phosphatase MupP Completes the Pseudomonas Peptidoglycan Recycling Pathway Leading to Intrinsic Fosfomycin Resistance

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Marina Borisova ◽  
Jonathan Gisin ◽  
Christoph Mayer
Keyword(s):  
Cell Wall ◽  
De Novo ◽  
Gram Negative Bacteria ◽  
Salvage Pathway ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
E Coli ◽  
A Cell ◽  
Recycling Pathway ◽  
Novel Drug

ABSTRACT Bacterial cells are encased in and stabilized by a netlike peptidoglycan (PGN) cell wall that undergoes turnover during bacterial growth. PGN turnover fragments are frequently salvaged by the cells via a pathway referred to as PGN recycling. Two different routes for the recycling of the cell wall sugar N-acetylmuramic acid (MurNAc) have been recognized in bacteria. In Escherichia coli and related enterobacteria, as well as in most Gram-positive bacteria, MurNAc is recovered via a catabolic route requiring a MurNAc 6-phosphate etherase (MurQ in E. coli) enzyme. However, many Gram-negative bacteria, including Pseudomonas species, lack a MurQ ortholog and use an alternative, anabolic recycling route that bypasses the de novo biosynthesis of uridyldiphosphate (UDP)-MurNAc, the first committed precursor of PGN. Bacteria featuring the latter pathway become intrinsically resistant to the antibiotic fosfomycin, which targets the de novo biosynthesis of UDP-MurNAc. We report here the identification and characterization of a phosphatase enzyme, named MupP, that had been predicted to complete the anabolic recycling pathway of Pseudomonas species but has remained unknown so far. It belongs to the large haloacid dehalogenase family of phosphatases and specifically converts MurNAc 6-phosphate to MurNAc. A ΔmupP mutant of Pseudomonas putida was highly susceptible to fosfomycin, accumulated large amounts of MurNAc 6-phosphate, and showed lower levels of UDP-MurNAc than wild-type cells, altogether consistent with a role for MupP in the anabolic PGN recycling route and as a determinant of intrinsic resistance to fosfomycin. IMPORTANCE Many Gram-negative bacteria, but not E. coli, make use of a cell wall salvage pathway that contributes to the pool of UDP-MurNAc, the first committed precursor of cell wall synthesis in bacteria. This salvage pathway is of particular interest because it confers intrinsic resistance to the antibiotic fosfomycin, which blocks de novo UDP-MurNAc biosynthesis. Here we identified and characterized a previously missing enzyme within the salvage pathway, the MurNAc 6-phosphate phosphatase MupP of P. putida. MupP, together with the other enzymes of the anabolic recycling pathway, AnmK, AmgK, and MurU, yields UDP-MurNAc, renders bacteria intrinsically resistant to fosfomycin, and thus may serve as a novel drug target for antimicrobial therapy. IMPORTANCE Many Gram-negative bacteria, but not E. coli, make use of a cell wall salvage pathway that contributes to the pool of UDP-MurNAc, the first committed precursor of cell wall synthesis in bacteria. This salvage pathway is of particular interest because it confers intrinsic resistance to the antibiotic fosfomycin, which blocks de novo UDP-MurNAc biosynthesis. Here we identified and characterized a previously missing enzyme within the salvage pathway, the MurNAc 6-phosphate phosphatase MupP of P. putida. MupP, together with the other enzymes of the anabolic recycling pathway, AnmK, AmgK, and MurU, yields UDP-MurNAc, renders bacteria intrinsically resistant to fosfomycin, and thus may serve as a novel drug target for antimicrobial therapy.

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