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Nature Microbiology Oct 2022The bacterial division apparatus catalyses the synthesis and remodelling of septal peptidoglycan (sPG) to build the cell wall layer that fortifies the daughter cell...
The bacterial division apparatus catalyses the synthesis and remodelling of septal peptidoglycan (sPG) to build the cell wall layer that fortifies the daughter cell poles. Understanding of this essential process has been limited by the lack of native three-dimensional views of developing septa. Here, we apply state-of-the-art cryogenic electron tomography (cryo-ET) and fluorescence microscopy to visualize the division site architecture and sPG biogenesis dynamics of the Gram-negative bacterium Escherichia coli. We identify a wedge-like sPG structure that fortifies the ingrowing septum. Experiments with strains defective in sPG biogenesis revealed that the septal architecture and mode of division can be modified to more closely resemble that of other Gram-negative (Caulobacter crescentus) or Gram-positive (Staphylococcus aureus) bacteria, suggesting that a conserved mechanism underlies the formation of different septal morphologies. Finally, analysis of mutants impaired in amidase activation (ΔenvC ΔnlpD) showed that cell wall remodelling affects the placement and stability of the cytokinetic ring. Taken together, our results support a model in which competition between the cell elongation and division machineries determines the shape of cell constrictions and the poles they form. They also highlight how the activity of the division system can be modulated to help generate the diverse array of shapes observed in the bacterial domain.
Topics: Amidohydrolases; Cell Division; Cell Shape; Cell Wall; Escherichia coli; Peptidoglycan
PubMed: 36097171
DOI: 10.1038/s41564-022-01210-z -
Applied Microbiology and Biotechnology Oct 2022Peptidoglycan-degrading enzymes are a group of proteins intensively studied as novel antibacterials, with some of them having reached pre-clinical and clinical stages of...
Peptidoglycan-degrading enzymes are a group of proteins intensively studied as novel antibacterials, with some of them having reached pre-clinical and clinical stages of research. Many peptidoglycan-degrading enzymes have modular organization and consist of a catalytic and a cell wall binding domain. This property has been exploited in enzyme engineering efforts, and many new peptidoglycan-degrading enzymes were generated through domain exchange. However, rational combination of domains from different enzymes is still challenging since relative contribution of every domain to the cumulative bacteriolytic activity is not yet clearly understood. In this work, we investigated the influence of ionic strength and pH on the catalytic efficiency and cell binding of peptidoglycan-degrading enzyme lysostaphin and how this influence is reflected in the lysostaphin bacteriolytic activity. Contrary to generally accepted view, lysostaphin domains are not completely independent and their combination within one protein leads to increased bacteriolytic activity with increasing NaCl concentration, despite both catalysis and cell binding being inhibited by NaCl. This effect is likely mediated by changes in conformation of bacterial cell wall peptidoglycan rather than the physical inter-domain interaction. KEY POINTS: • NaCl enhances bacteriolytic activity of lysostaphin but not of its catalytic domain. • Catalytic activity and cell binding of lysostaphin are inhibited by NaCl. • Peptidoglycan conformation likely affects lysostaphin bacteriolytic activity.
Topics: Catalysis; Cell Wall; Hydrogen-Ion Concentration; Lysostaphin; Peptidoglycan; Sodium Chloride; Staphylococcus aureus
PubMed: 36112205
DOI: 10.1007/s00253-022-12173-w -
Molecular Microbiology Mar 2020The peptidoglycan (PG), as the exoskeleton of most prokaryotes, maintains a defined shape and ensures cell integrity against the high internal turgor pressure. These... (Review)
Review
The peptidoglycan (PG), as the exoskeleton of most prokaryotes, maintains a defined shape and ensures cell integrity against the high internal turgor pressure. These important roles have attracted researchers to target PG metabolism in order to control bacterial infections. Most studies, however, have been performed in bacteria grown under laboratory conditions, leading to only a partial view on how the PG is synthetized in natural environments. As a case in point, PG metabolism and its regulation remain poorly understood in symbiotic and pathogenic bacteria living inside eukaryotic cells. This review focuses on the PG metabolism of intracellular bacteria, emphasizing the necessity of more in vivo studies involving the analysis of enzymes produced in the intracellular niche and the isolation of PG from bacteria residing within eukaryotic cells. The review also points to persistent infections caused by some intracellular bacterial pathogens and the extent at which the PG could contribute to establish such physiological state. Based on recent evidences, I speculate on the idea that certain structural features of the PG may facilitate attenuation of intracellular growth. Lastly, I discuss recent findings in endosymbionts supporting a cooperation between host and bacterial enzymes to assemble a mature PG.
Topics: Bacteria; Bacterial Infections; Bacterial Proteins; Cell Wall; Eukaryotic Cells; Host-Pathogen Interactions; Humans; Peptidoglycan; Symbiosis; Virulence
PubMed: 32185832
DOI: 10.1111/mmi.14452 -
Bulletin of Experimental Biology and... Dec 2021We studied the effect of bacterial wall peptidoglycan of 7 bacterial species on the competitive properties of human-associated microorganisms. Addition of peptidoglycan...
We studied the effect of bacterial wall peptidoglycan of 7 bacterial species on the competitive properties of human-associated microorganisms. Addition of peptidoglycan to the culture medium did not change the growth characteristics of the test cultures; however, an increase in the antagonism and hydrophobicity of Bifidobacterium sp. and Enterococcus sp. was observed, while the effect on enterobacteria was predominantly indifferent or inhibitory. The effect did not depend much on the source of peptidoglycan and was equally manifested on both indigenous and probiotic strains. The observed new property of peptidoglycan indicates its participation in the formation and functioning of microbiota. The obtained data on the regulation of the properties of microorganisms provide new possibilities for the correction and maintenance of host homeostasis through host-associated microbiota.
Topics: Antibiosis; Bacillus subtilis; Bacterial Proteins; Bifidobacterium; Candida; Cell Wall; Enterobacter; Enterococcus faecalis; Escherichia coli; Female; Humans; Lacticaseibacillus casei; Microbiological Techniques; Peptidoglycan; Staphylococcus aureus
PubMed: 34855091
DOI: 10.1007/s10517-021-05356-4 -
MBio Aug 2022Bacteria in general serve two main tasks: cell growth and division. Both processes include peptidoglycan extension to allow cell expansion and to form the poles of the...
Bacteria in general serve two main tasks: cell growth and division. Both processes include peptidoglycan extension to allow cell expansion and to form the poles of the daughter cells, respectively. The cyanobacterium forms filaments of communicated cells in which the outer membrane and the peptidoglycan sacculus, which is engrossed in the intercellular regions between contiguous cells, are continuous along the filament. During the growth of , peptidoglycan incorporation was weak at the cell periphery. During cell division, midcell peptidoglycan incorporation matched the localization of the divisome, and incorporation persisted in the intercellular septa, even after the division was completed. MreB, MreC, and MreD were located throughout the cell periphery and, in contrast to other bacteria, also to the divisome all along midcell peptidoglycan growth. In mutants bearing inactivated , or genes, which showed conspicuous alterations in the filament morphology, consecutive septal bands of peptidoglycan growth were frequently not parallel to each other and were irregularly spaced along the filament, reproducing the disposition of the Z-ring. Both lateral and septal growth was impaired in strains down-expressing Z-ring components, and MreB and MreD appeared to directly interact with some divisome components. We propose that, in , association with the divisome is a way for localization of MreB, MreC, and MreD at the cell poles, where they regulate lateral, midcell, and septal peptidoglycan growth with the latter being involved in localization and maintenance of the intercellular septal-junction protein structures that mediate cell-cell communication along the filament. Peptidoglycan surrounds the bacterial cell, being essential for the determination of the bacterium-specific morphology and survival. Peptidoglycan growth has been thoroughly investigated in some model rod-shaped bacteria, and more recently some representatives with disparate morphologies became into focus, revealing that patterns of peptidoglycan growth are much more diverse than previously anticipated. forms filaments of communicated cells exhibiting features of multicellular organisms, such as the production of morphogens and coupled circadian oscillations. Here, we showed that presented a distinct pattern of peptidoglycan growth characterized by continuous incorporation of material at the polar intercellular regions, contributing to assembling and maintaining the protein complexes that expand the septal peptidoglycan mediating intercellular molecular exchange in the filament.
Topics: Anabaena; Bacterial Proteins; Cell Division; Cell Wall; Peptidoglycan
PubMed: 35876506
DOI: 10.1128/mbio.01165-22 -
MBio Jul 2019species are obligate intracellular bacteria lacking a classical peptidoglycan sacculus but relying on peptidoglycan synthesis for cytokinesis. While septal...
species are obligate intracellular bacteria lacking a classical peptidoglycan sacculus but relying on peptidoglycan synthesis for cytokinesis. While septal peptidoglycan biosynthesis seems to be regulated by MreB actin and its membrane anchor RodZ rather than FtsZ tubulin in , the mechanism of peptidoglycan remodeling is poorly understood. An amidase conserved in is able to cleave peptide stems in peptidoglycan, but it is not clear how peptidoglycan glycan strands are cleaved since no classical lytic transglycosylase is encoded in chlamydial genomes. However, a protein containing a SpoIID domain, known to possess transglycosylase activity in , is conserved in We show here that the SpoIID homologue of the -related pathogen is a septal peptidoglycan-binding protein. Moreover, we demonstrate that SpoIID acts as a lytic transglycosylase on peptidoglycan and as a muramidase on denuded glycan strands As SpoIID-like proteins are widespread in nonsporulating bacteria, SpoIID might commonly be a septal peptidoglycan remodeling protein in bacteria, including obligate intracellular pathogens, and thus might represent a promising drug target. species are obligate intracellular bacteria and important human pathogens that have a minimal division machinery lacking the proteins that are essential for bacterial division in other species, such as FtsZ. Chlamydial division requires synthesis of peptidoglycan, which forms a ring at the division septum and is rapidly turned over. However, little is known of peptidoglycan degradation, because many peptidoglycan-degrading enzymes are not encoded by chlamydial genomes. Here we show that an homologue of SpoIID, a peptidoglycan-degrading enzyme involved in sporulation of bacteria such as , is expressed in , localizes at the division septum, and degrades peptidoglycan , indicating that SpoIID is not only involved in sporulation but also likely implicated in division of some bacteria.
Topics: Amino Acid Sequence; Bacterial Proteins; Cell Division; Chlamydia; Chlamydia Infections; Chromatography, High Pressure Liquid; Gene Expression; Humans; Peptidoglycan; Protein Binding; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spores, Bacterial
PubMed: 31311880
DOI: 10.1128/mBio.01128-19 -
The Journal of Biological Chemistry Jun 2023Microbial recognition is a key step in regulating the immune signaling pathways of multicellular organisms. Peptidoglycan, a component of the bacterial cell wall,...
Microbial recognition is a key step in regulating the immune signaling pathways of multicellular organisms. Peptidoglycan, a component of the bacterial cell wall, exhibits immune stimulating activity in both plants and animals. Lysin motif domain (LysMD) family proteins are ancient peptidoglycan receptors that function in bacteriophage and plants. This report focuses on defining the role of LysMD-containing proteins in animals. Here, we characterize a novel transmembrane LysMD family protein. Loss-of-function mutations at the lysMD3/4 locus in Drosophila are associated with systemic innate immune activation following challenge, so we refer to this gene as immune active (ima). We show that Ima selectively binds peptidoglycan, is enriched in cell membranes, and is necessary to regulate terminal innate immune effectors through an NF-kB-dependent pathway. Hence, Ima fulfills the key criteria of a peptidoglycan pattern recognition receptor. The human Ima ortholog, hLysMD3, exhibits similar biochemical properties. Together, these findings establish LysMD3/4 as the founding member of a novel family of animal peptidoglycan recognition proteins.
Topics: Animals; Humans; Cell Wall; Drosophila melanogaster; Drosophila Proteins; Immunity, Innate; Peptidoglycan; Membrane Proteins
PubMed: 37116706
DOI: 10.1016/j.jbc.2023.104758 -
Acta Biochimica Polonica Sep 2020The insect immune system is responsible for maintaining the homeostasis of organisms. If the pathogen is able to breach the defensive barriers of the host, cellular and... (Review)
Review
The insect immune system is responsible for maintaining the homeostasis of organisms. If the pathogen is able to breach the defensive barriers of the host, cellular and humoral mechanisms are triggered. Initiation of effective defence response is possible thanks to pathogen-associated molecular patterns, among which peptidoglycan recognition proteins play a prominent role. They recognize pathogen-associated molecular patterns and some of them also have enzymatic activity. The main aim of peptidoglycan recognition proteins is to activate pathways regulating the synthesis of immune peptides. Some of the peptidoglycan recognition proteins are involved in the phagocytosis process, activation of the prophenoloxidase cascade, and regulation of the xenophagy process. The structural diversity and high specificity of peptidoglycan recognition proteins suggests that they can serve many previously unknown functions in insect's systemic response.
Topics: Animals; Carrier Proteins; Catechol Oxidase; Enzyme Precursors; Host-Pathogen Interactions; Immunity, Innate; Insect Proteins; Insecta; Pathogen-Associated Molecular Pattern Molecules; Peptidoglycan; Receptors, Pattern Recognition
PubMed: 32940448
DOI: 10.18388/abp.2020_5345 -
Nature Jun 2020The primary structural component of the bacterial cell wall is peptidoglycan, which is essential for viability and the synthesis of which is the target for crucial...
The primary structural component of the bacterial cell wall is peptidoglycan, which is essential for viability and the synthesis of which is the target for crucial antibiotics. Peptidoglycan is a single macromolecule made of glycan chains crosslinked by peptide side branches that surrounds the cell, acting as a constraint to internal turgor. In Gram-positive bacteria, peptidoglycan is tens of nanometres thick, generally portrayed as a homogeneous structure that provides mechanical strength. Here we applied atomic force microscopy to interrogate the morphologically distinct Staphylococcus aureus and Bacillus subtilis species, using live cells and purified peptidoglycan. The mature surface of live cells is characterized by a landscape of large (up to 60 nm in diameter), deep (up to 23 nm) pores constituting a disordered gel of peptidoglycan. The inner peptidoglycan surface, consisting of more nascent material, is much denser, with glycan strand spacing typically less than 7 nm. The inner surface architecture is location dependent; the cylinder of B. subtilis has dense circumferential orientation, while in S. aureus and division septa for both species, peptidoglycan is dense but randomly oriented. Revealing the molecular architecture of the cell envelope frames our understanding of its mechanical properties and role as the environmental interface, providing information complementary to traditional structural biology approaches.
Topics: Bacillus subtilis; Cell Wall; Microbial Viability; Microscopy, Atomic Force; Peptidoglycan; Staphylococcus aureus
PubMed: 32523118
DOI: 10.1038/s41586-020-2236-6 -
Microbiology Spectrum Oct 2022Diaminopimelic acid (DAP) is a unique component of the cell wall of Gram-negative bacteria. It is also an important component of organic matter and is widely utilized by...
Diaminopimelic acid (DAP) is a unique component of the cell wall of Gram-negative bacteria. It is also an important component of organic matter and is widely utilized by microbes in the world's oceans. However, neither DAP concentrations nor marine DAP-utilizing microbes have been investigated. Here, DAP concentrations in seawater were measured and the diversity of marine DAP-utilizing bacteria and the mechanisms for their DAP metabolism were investigated. Free DAP concentrations in seawater, from surface to a 5,000 m depth, were found to be between 0.61 μM and 0.96 μM in the western Pacific Ocean. DAP-utilizing bacteria from 20 families in 4 phyla were recovered from the western Pacific seawater and 14 strains were further isolated, in which bacteria were dominant. Based on genomic and transcriptomic analyses combined with gene deletion and activity detection, DAP decarboxylase (LysA), which catalyzes the decarboxylation of DAP to form lysine, was found to be a key and specific enzyme involved in DAP metabolism in the isolated strains. Interrogation of the Oceans database found that most LysA-like sequences (92%) are from , which are widely distributed in multiple habitats. This study provides an insight into DAP metabolism by marine bacteria in the ocean and contributes to our understanding of the mineralization and recycling of DAP by marine bacteria. DAP is a unique component of peptidoglycan in Gram-negative bacterial cell walls. Due to the large number of marine Gram-negative bacteria, DAP is an important component of marine organic matter. However, it remains unclear how DAP is metabolized by marine microbes. This study investigated marine DAP-utilizing bacteria by cultivation and bioinformational analysis and examined the mechanism of DAP metabolism used by marine bacteria. The results demonstrate that bacteria are likely to be an important DAP-utilizing group in the ocean and that DAP decarboxylase is a key enzyme involved in DAP metabolism. This study also sheds light on the mineralization and recycling of DAP driven by bacteria.
Topics: Bacteria; Carboxy-Lyases; Diaminopimelic Acid; Gram-Negative Bacteria; Lysine; Peptidoglycan
PubMed: 36040174
DOI: 10.1128/spectrum.00691-22