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Molecular Microbiology Jul 2013The peptidoglycan (PG) cell wall is a unique macromolecule responsible for both shape determination and cellular integrity under osmotic stress in virtually all... (Review)
Review
The peptidoglycan (PG) cell wall is a unique macromolecule responsible for both shape determination and cellular integrity under osmotic stress in virtually all bacteria. A quantitative understanding of the relationships between PG architecture, morphogenesis, immune system activation and pathogenesis can provide molecular-scale insights into the function of proteins involved in cell wall synthesis and cell growth. High-performance liquid chromatography (HPLC) has played an important role in our understanding of the structural and chemical complexity of the cell wall by providing an analytical method to quantify differences in chemical composition. Here, we present a primer on the basic chemical features of wall structure that can be revealed through HPLC, along with a description of the applications of HPLC PG analyses for interpreting the effects of genetic and chemical perturbations to a variety of bacterial species in different environments. We describe the physical consequences of different PG compositions on cell shape, and review complementary experimental and computational methodologies for PG analysis. Finally, we present a partial list of future targets of development for HPLC and related techniques.
Topics: Bacteria; Cell Wall; Chromatography, High Pressure Liquid; Peptidoglycan
PubMed: 23679048
DOI: 10.1111/mmi.12266 -
Molecular Microbiology Mar 2014Peptidoglycan performs the essential role of resisting turgor in the cell walls of most bacteria. It determines cell shape, and its biosynthesis is the target for many... (Review)
Review
Peptidoglycan performs the essential role of resisting turgor in the cell walls of most bacteria. It determines cell shape, and its biosynthesis is the target for many important antibiotics. The fundamental chemical building blocks of peptidoglycan are conserved: repeating disaccharides cross-linked by peptides. However, these blocks come in many varieties and can be assembled in different ways. So beyond the fundamental similarity, prodigious chemical, organizational and architectural diversity is revealed. Here, we track the evolution of our current understanding of peptidoglycan and underpinning technical and methodological developments. The origin and function of chemical diversity is discussed with respect to some well-studied example species. We then explore how this chemistry is manifested in elegant and complex peptidoglycan organization and how this is interpreted in different and sometimes controversial architectural models. We contend that emerging technology brings about the possibility of achieving a complete understanding of peptidoglycan chemistry, through architecture, to the way in which diverse species and populations of cells meet the challenges of maintaining viability and growth within their environmental niches, by exploiting the bioengineering versatility of peptidoglycan.
Topics: Bacteria; Cell Wall; Imaging, Three-Dimensional; Models, Molecular; Peptidoglycan
PubMed: 24405365
DOI: 10.1111/mmi.12513 -
FEMS Microbiology Reviews Nov 2007Bacterial peptidoglycan amidases are a large and diverse group of enzymes. During the last few years, genomic sequence information has accumulated to an extent such that... (Review)
Review
Bacterial peptidoglycan amidases are a large and diverse group of enzymes. During the last few years, genomic sequence information has accumulated to an extent such that lists of proven or predicted peptidoglycan amidases can now be expected to be fairly complete. Moreover, representative crystal structures for most groups of phylogenetically related peptidoglycan amidases have been solved. Here, sequence and structural information is combined with published biochemical findings to demonstrate that (a) peptidoglycan amidases have evolved for almost every bond that occurs in peptidoglycan, (b) there are enzymes that share the fold, yet cleave different bonds and (c) there are enzymes that have entirely different folds and must have evolved independently, and yet cleave the same peptide bond. It is shown that despite these complications, some rules can be deduced from the available biochemical and structural information that can be useful to predict the specificity of hypothetical peptidoglycan hydrolases, for which only sequence information is available.
Topics: Amidohydrolases; Bacillus subtilis; Bacterial Physiological Phenomena; Bacterial Proteins; Escherichia coli; Peptidoglycan; Protein Structure, Tertiary; Structure-Activity Relationship
PubMed: 17888003
DOI: 10.1111/j.1574-6976.2007.00084.x -
Plant Physiology Aug 2022Accumulating evidence suggests that peptidoglycan, consistent with a bacterial cell wall, is synthesized around the chloroplasts of many photosynthetic eukaryotes, from...
Accumulating evidence suggests that peptidoglycan, consistent with a bacterial cell wall, is synthesized around the chloroplasts of many photosynthetic eukaryotes, from glaucophyte algae to early-diverging land plants including pteridophyte ferns, but the biosynthetic pathway has not been demonstrated. Here, we employed mass spectrometry and enzymology in a two-fold approach to characterize the synthesis of peptidoglycan in chloroplasts of the moss Physcomitrium (Physcomitrella) patens. To drive the accumulation of peptidoglycan pathway intermediates, P. patens was cultured with the antibiotics fosfomycin, D-cycloserine, and carbenicillin, which inhibit key peptidoglycan pathway proteins in bacteria. Mass spectrometry of the trichloroacetic acid-extracted moss metabolome revealed elevated levels of five of the predicted intermediates from uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) through the uridine diphosphate N-acetylmuramic acid (UDP-MurNAc)-D,L-diaminopimelate (DAP)-pentapeptide. Most Gram-negative bacteria, including cyanobacteria, incorporate meso-diaminopimelic acid (D,L-DAP) into the third residue of the stem peptide of peptidoglycan, as opposed to L-lysine, typical of most Gram-positive bacteria. To establish the specificity of D,L-DAP incorporation into the P. patens precursors, we analyzed the recombinant protein UDP-N-acetylmuramoyl-L-alanyl-D-glutamate-2,6-diaminopimelate ligase (MurE) from both P. patens and the cyanobacterium Anabaena sp. (Nostoc sp. strain PCC 7120). Both ligases incorporated D,L-DAP in almost complete preference to L-Lys, consistent with the mass spectrophotometric data, with catalytic efficiencies similar to previously documented Gram-negative bacterial MurE ligases. We discuss how these data accord with the conservation of active site residues common to DL-DAP-incorporating bacterial MurE ligases and of the probability of a horizontal gene transfer event within the plant peptidoglycan pathway.
Topics: Bacteria; Cell Wall; Chloroplasts; Gram-Negative Bacteria; Ligases; Lysine; Peptidoglycan; Uridine Diphosphate
PubMed: 35471580
DOI: 10.1093/plphys/kiac176 -
Nature Jun 2022
Topics: Bacteria; Cell Membrane; Peptidoglycan
PubMed: 35760964
DOI: 10.1038/d41586-022-01739-3 -
Organic & Biomolecular Chemistry Nov 2021We report the automated glycan assembly (AGA) of different oligosaccharide fragments of the bacterial peptidoglycan (PGN) backbone. Iterative addition on a solid support...
We report the automated glycan assembly (AGA) of different oligosaccharide fragments of the bacterial peptidoglycan (PGN) backbone. Iterative addition on a solid support of an acetyl glucosamine and a new muramic acid building block is followed by cleavage from the solid support and final deprotection providing 10 oligosaccharides up to six units.
Topics: Automation; Carbohydrate Sequence; Peptidoglycan; Polysaccharides
PubMed: 34734957
DOI: 10.1039/d1ob01987b -
Cellular and Molecular Life Sciences :... Jun 2007Infection of bacteria triggers innate immune defense reactions in Drosophila. So far, the only bacterial component known to be recognized by the insect innate immune... (Review)
Review
Infection of bacteria triggers innate immune defense reactions in Drosophila. So far, the only bacterial component known to be recognized by the insect innate immune system is peptidoglycan, one of the most abundant constituents of the bacterial cell wall. Insects use peptidoglycan recognition proteins to detect peptidoglycan and to activate innate immune responses. Such specialized peptidoglycan receptors appear to have evolved from phage enzymes that hydrolyze bacterial cell walls. They are able to bind specific peptidoglycan molecules with distinct chemical moieties and activate innate immune pathways by interacting with other signaling proteins. Recent X-ray crystallographic studies of the peptidoglycan recognition proteins LCa, and LCx bound to peptidoglycan have provided structural insights into recognition of peptidoglycan and activation of innate immunity in insects.
Topics: Animals; Binding Sites; Carrier Proteins; Drosophila melanogaster; Immunity, Innate; Models, Molecular; Molecular Structure; Peptidoglycan; Protein Conformation; Signal Transduction
PubMed: 17417689
DOI: 10.1007/s00018-007-6567-3 -
The Journal of Neuroscience : the... Oct 2022Probing the external world is essential for eukaryotes to distinguish beneficial from pathogenic micro-organisms. If it is clear that the main part of this task falls to...
Probing the external world is essential for eukaryotes to distinguish beneficial from pathogenic micro-organisms. If it is clear that the main part of this task falls to the immune cells, recent work shows that neurons can also detect microbes, although the molecules and mechanisms involved are less characterized. In detection of bacteria-derived peptidoglycan by pattern recognition receptors of the peptidoglycan recognition protein (PGRP) family expressed in immune cells triggers nuclear factor-κB (-κB)/immune deficiency (IMD)-dependent signaling. We show here that one PGRP protein, called PGRP-LB, is expressed in bitter gustatory neurons of proboscises. calcium imaging in female flies reveals that the PGRP/IMD pathway is cell-autonomously required in these neurons to transduce the peptidoglycan signal. We finally show that NF-κB/IMD pathway activation in bitter-sensing gustatory neurons influences fly behavior. This demonstrates that a major immune response elicitor and signaling module are required in the peripheral nervous system to sense the presence of bacteria in the environment. In addition to the classical immune response, eukaryotes rely on neuronally controlled mechanisms to detect microbes and engage in adapted behaviors. However, the mechanisms of microbe detection by the nervous system are poorly understood. Using genetic analysis and calcium imaging, we demonstrate here that bacteria-derived peptidoglycan can activate bitter gustatory neurons. We further show that this response is mediated by the PGRP-LC membrane receptor and downstream components of a noncanonical NF-κB signaling cascade. Activation of this signaling cascade triggers behavior changes. These data demonstrate that bitter-sensing neurons and immune cells share a common detection and signaling module to either trigger the production of antibacterial effectors or to modulate the behavior of flies that are in contact with bacteria. Because peptidoglycan detection doesn't mobilize the known gustatory receptors, it also demonstrates that taste perception is much more complex than anticipated.
Topics: Animals; Female; Drosophila; Peptidoglycan; NF-kappa B; Calcium; Bacteria; Neurons
PubMed: 36414007
DOI: 10.1523/JNEUROSCI.2437-21.2022 -
Zentralblatt Fur Veterinarmedizin.... Aug 1982
Review
Topics: Adjuvants, Immunologic; Anti-Bacterial Agents; B-Lymphocytes; Bacteria; Cell Wall; Chemical Phenomena; Chemistry; Cytotoxicity, Immunologic; Epitopes; Peptidoglycan; T-Lymphocytes
PubMed: 6183847
DOI: No ID Found -
Methods in Molecular Biology (Clifton,... 2017Most gene clusters encoding multiprotein complexes of the bacterial cell envelope, such as conjugation and secretion systems, Type IV pili, and flagella, bear a gene...
Most gene clusters encoding multiprotein complexes of the bacterial cell envelope, such as conjugation and secretion systems, Type IV pili, and flagella, bear a gene encoding an enzyme with peptidoglycan hydrolase activity. These enzymes are usually glycoside hydrolases that cleave the glycan chains of the peptidoglycan. Their activities are spatially controlled to avoid cell lysis and to create localized rearrangement of the cell wall. This is assured by interaction with the structural subunits of the apparatus. Here we describe protocols to test the peptidoglycan hydrolase activity of these proteins in vitro and in solution.
Topics: Enzyme Activation; Hydrolysis; N-Acetylmuramoyl-L-alanine Amidase; Nephelometry and Turbidimetry; Peptidoglycan; Staining and Labeling
PubMed: 28667610
DOI: 10.1007/978-1-4939-7033-9_12