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Frontiers in Immunology 2023Bacterium-like particles (BLPs) are hollow peptidoglycan particles obtained from food-grade inactivated by hot acid. With the advantage of easy preparation, high... (Review)
Review
Bacterium-like particles (BLPs) are hollow peptidoglycan particles obtained from food-grade inactivated by hot acid. With the advantage of easy preparation, high safety, great stability, high loading capacity, and high mucosal delivery efficiency, BLPs can load and display proteins on the surface with the help of protein anchor (PA), making BLPs a proper delivery system. Owning to these features, BLPs are widely used in the development of adjuvants, vaccine carriers, virus/antigens purification, and enzyme immobilization. This review has attempted to gather a full understanding of the technical composition, characteristics, applications. The mechanism by which BLPs induces superior adaptive immune responses is also discussed. Besides, this review tracked the latest developments in the field of BLPs, including -derived BLPs and novel anchors. Finally, the main limitations and proposed breakthrough points to further enhance the immunogenicity of BLPs vaccines were discussed, providing directions for future research. We hope that further developments in the field of antigen delivery of subunit vaccines or others will benefit from BLPs.
Topics: Bacteria; Antigens; Adjuvants, Immunologic; Vaccines, Subunit; Probiotics
PubMed: 37868963
DOI: 10.3389/fimmu.2023.1263586 -
Angewandte Chemie (International Ed. in... Apr 2024Peptidoglycan, an essential component within the cell walls of virtually all bacteria, is composed of glycan strands linked by stem peptides that contain D-amino acids.... (Review)
Review
Peptidoglycan, an essential component within the cell walls of virtually all bacteria, is composed of glycan strands linked by stem peptides that contain D-amino acids. The peptidoglycan biosynthesis machinery exhibits high tolerance to various D-amino acid derivatives. D-amino acid derivatives with different functionalities can thus be specifically incorporated into and label the peptidoglycan of bacteria, but not the host mammalian cells. This metabolic labeling strategy is highly selective, highly biocompatible, and broadly applicable, which has been utilized in various fields. This review introduces the metabolic labeling strategies of peptidoglycan by using D-amino acid derivatives, including one-step and two-step strategies. In addition, we emphasize the various applications of D-amino acid derivative-based metabolic labeling, including bacterial peptidoglycan visualization (existence, biosynthesis, and dynamics, etc.), bacterial visualization (including bacterial imaging and visualization of growth and division, metabolic activity, antibiotic susceptibility, etc.), pathogenic bacteria-targeted diagnostics and treatment (positron emission tomography (PET) imaging, photodynamic therapy, photothermal therapy, gas therapy, immunotherapy, etc.), and live bacteria-based therapy. Finally, a summary of this metabolic labeling and an outlook is provided.
Topics: Peptidoglycan; Bacteria; Amino Acids; Cell Wall
PubMed: 38284300
DOI: 10.1002/anie.202319400 -
Microorganisms Feb 2024The phylum is comprised of obligate intracellular bacteria including human pathogens such as and lesser-known -related bacteria like or . Despite broad differences,... (Review)
Review
The phylum is comprised of obligate intracellular bacteria including human pathogens such as and lesser-known -related bacteria like or . Despite broad differences, these bacteria share a similar development including a persistent state induced using stressors such as immune responses, nutrient starvation, or penicillin introduction. In microbiology, this persistent state is identified by enlarged bacteria, called aberrant bodies, which are unable to divide but are able to survive and resume the developmental cycle upon clearance of the stressor. Clinically, chlamydial persistence is thought to be linked to chronic disease and long-term infections with pathogenic strains. This review aims to share and discuss the latest discoveries made on the little-known mechanisms that take place during stress response. The results indicate that an inter-linked homeostasis between iron and tryptophan is required for effective bacterial proliferation. During stress, attempt to compensate by inducing tight regulations of the tryptophan and iron acquisition operons. These compensations allow bacterial survival but result in the halting of cell division. As cell division is tightly linked to peptidoglycan synthesis and regulation, treatment with β-lactamase inhibitors can also exhibit an aberrant body phenotype.
PubMed: 38543546
DOI: 10.3390/microorganisms12030495 -
MicrobiologyOpen Oct 2023The bacterial cell envelope is involved in all stages of infection and the study of its components and structures is important to understand how bacteria interact with... (Review)
Review
The bacterial cell envelope is involved in all stages of infection and the study of its components and structures is important to understand how bacteria interact with the extracellular milieu. Thanks to new techniques that focus on identifying bacterial surface proteins, we now better understand the specific components involved in host-pathogen interactions. In the fight against the deleterious effects of pathogenic bacteria, bacterial surface proteins (at the cell envelope) are important targets as they play crucial roles in the colonization and infection of host tissues. These surface proteins serve functions such as protection, secretion, biofilm formation, nutrient intake, metabolism, and virulence. Bacteria use different mechanisms to associate proteins to the cell surface via posttranslational modification, such as the addition of a lipid moiety to create lipoproteins and attachment to the peptidoglycan layer by sortases. In this review, we focus on these types of proteins (and provide examples of others) that are associated with the bacterial cell envelope by posttranslational modifications and their roles in plant infection.
Topics: Membrane Proteins; Bacteria; Bacterial Proteins; Lipoproteins; Cell Wall
PubMed: 37877658
DOI: 10.1002/mbo3.1382 -
Bioscience, Biotechnology, and... May 2024In bacteria, d-amino acids are primarily synthesized from l-amino acids by amino acid racemases, but some bacteria use d-amino acid aminotransferases to synthesize... (Review)
Review
In bacteria, d-amino acids are primarily synthesized from l-amino acids by amino acid racemases, but some bacteria use d-amino acid aminotransferases to synthesize d-amino acids. d-Amino acids are peptidoglycan components in the cell wall involved in several physiological processes, such as bacterial growth, biofilm dispersal, and peptidoglycan metabolism. Therefore, their metabolism and physiological roles have attracted increasing attention. Recently, we identified novel bacterial d-amino acid metabolic pathways, which involve amino acid racemases, with broad substrate specificity, as well as multifunctional enzymes with d-amino acid-metabolizing activity. Here, I review these multifunctional enzymes and their related d- and l-amino acid metabolic pathways in Escherichia coli and the hyperthermophile Thermotoga maritima.
Topics: Amino Acids; Thermotoga maritima; Escherichia coli; Substrate Specificity; Amino Acid Isomerases; Peptidoglycan; Transaminases; Bacterial Proteins
PubMed: 38439669
DOI: 10.1093/bbb/zbae027 -
Applied and Environmental Microbiology Jul 2023Phage-encoded endolysins are emerging antibacterial agents based on their ability to efficiently degrade peptidoglycan on Gram-positive bacteria, but the envelope...
Phage-encoded endolysins are emerging antibacterial agents based on their ability to efficiently degrade peptidoglycan on Gram-positive bacteria, but the envelope characteristics of Gram-negative bacteria limit their application. Engineering modifications of endolysins can improve the optimization of their penetrative and antibacterial properties. This study constructed a screening platform to screen for engineered Artificial-Bp7e (Art-Bp7e) endolysins with extracellular antibacterial activity against Escherichia coli. An oligonucleotide of 20 repeated NNK codons was inserted upstream of the endolysin gene to construct a chimeric endolysin library in the pColdTF vector. The chimeric Art-Bp7e proteins were expressed by transforming the plasmid library into E. coli BL21 and released by chloroform fumigation, and the protein activities were evaluated by the spotting method and the colony-counting method to screen for promising proteins. Sequence analysis showed that all screened proteins with extracellular activities had a chimeric peptide with a positive charge and an α-helical structure. Also, a representative protein, Art-Bp7e6, was further characterized. It exhibited broad antibacterial activity against E. coli (7/21), Salmonella enterica serovar Enteritidis (4/10), Pseudomonas aeruginosa (3/10), and even Staphylococcus aureus (1/10). In the transmembrane process, the chimeric peptide of Art-Bp7e6 depolarized the host cell envelope, increased the permeability of the cell, and facilitated the movement of Art-Bp7e6 across the envelope to hydrolyze the peptidoglycan. In conclusion, the screening platform successfully screened for chimeric endolysins with extracellular antibacterial activities against Gram-negative bacteria, which provides methodological support for the further screening of engineered endolysins with high extracellular activities against Gram-negative bacteria. Also, the established platform showed broad application prospects and can be used to screen various proteins. The presence of the envelope in Gram-negative bacteria limits the use of phage endolysins, and engineering endolysins is an efficient way to optimize their penetrative and antibacterial properties. We built a platform for endolysin engineering and screening. A random peptide was fused with the phage endolysin Bp7e to construct a chimeric endolysin library, and engineered Artificial-Bp7e (Art-Bp7e) endolysins with extracellular activity against Gram-negative bacteria were successfully screened from the library. The purposeful Art-Bp7e had a chimeric peptide with an abundant positive charge and an α-helical structure, which led Bp7e to acquire the ability for the extracellular lysis of Gram-negative bacteria and showed a broad lysis spectrum. The platform provides a huge library capacity without the limitations of reported proteins or peptides. It can be utilized for the further screening of optimal endolysins against Gram-negative bacteria as well as for the screening of additional proteins with specific modifications.
Topics: Bacteriophages; Escherichia coli; Peptidoglycan; Anti-Bacterial Agents; Gram-Negative Bacteria; Endopeptidases
PubMed: 37338346
DOI: 10.1128/aem.00581-23 -
The FEBS Journal Jun 2024Peptidoglycan DL-endopeptidases locally cleave the peptide stem of peptidoglycan in the bacterial cell wall. This process facilitates bacterial growth and division by...
Peptidoglycan DL-endopeptidases locally cleave the peptide stem of peptidoglycan in the bacterial cell wall. This process facilitates bacterial growth and division by loosening the rigid peptidoglycan layer. IseA binds to the active site of multiple DL-endopeptidases and inhibits excessive peptidoglycan degradation that leads to cell lysis. To better understand how IseA inhibits DL-endopeptidase activity, we determined the crystal structure of the peptidoglycan DL-endopeptidase CwlO/IseA complex and compared it with that of the peptidoglycan DL-endopeptidase LytE/IseA complex. Structural analyses showed significant differences between the hydrophobic pocket-binding residues of the DL-endopeptidases (F361 of CwlO and W237 of LytE). Additionally, binding assays showed that the F361 mutation of CwlO to the bulkier hydrophobic residue, tryptophan, increased its binding affinity for IseA, whereas mutation to alanine reduced the affinity. These analyses revealed that the hydrophobic pocket-binding residue of DL-endopeptidases determines IseA-binding affinity and is required for substrate-mimetic inhibition by IseA.
PubMed: 38840475
DOI: 10.1111/febs.17197 -
Probiotics and Antimicrobial Proteins Nov 2023Pesticides possess a pivotal role in the realm of agriculture and food manufacturing, as they effectively manage the proliferation of weeds, insects, plant pathogens,... (Review)
Review
Pesticides possess a pivotal role in the realm of agriculture and food manufacturing, as they effectively manage the proliferation of weeds, insects, plant pathogens, and microbial contaminations. They are valuable in some ways, but if misused, they can cause health issues like cancer, reproductive toxicity, neurological illnesses, and endocrine system disturbances. In this regard, practical methods for reducing pesticide residue in food should be used. For reducing pesticide residue in food processing, some strategies have been suggested. Recent research has been done on detoxification processes, including microorganisms like probiotics and their metabolites. The term "postbiotics" describes soluble substances, such as peptides, enzymes, teichoic acids, muropeptides generated from peptidoglycans, polysaccharides, proteins, and organic acids that are secreted by living bacteria or released after bacterial lysis. Due to their distinct chemical makeup, safe dosage guidelines, lengthy shelf lives, and presence of various signaling molecules that may have antioxidant, anti-inflammatory, anti-obesogenic, immunomodulatory, anti-hypertensive, and immunomodulatory effects, these postbiotics have attracted interest. They also can detoxify heavy metals, mycotoxins, and pesticides. Hydrolytic enzymes have been proposed as a potential mechanism for pesticide degradation. Postbiotics can also reduce reactive oxygen species production, enhance gastrointestinal barrier function, reduce inflammation, and modulate host xenobiotic metabolism. This review highlights pesticide residues in food products, definitions and safety aspect of postbiotics, as well as their biological role in detoxification of pesticides and the protective role of these compounds against the adverse effects of pesticides.
PubMed: 37934379
DOI: 10.1007/s12602-023-10184-1 -
Cold Spring Harbor Protocols Aug 2023Here, we describe a protocol for a colony polymerase chain reaction (PCR) method for The methodology involves the preparation of small lysates by using the enzyme...
Here, we describe a protocol for a colony polymerase chain reaction (PCR) method for The methodology involves the preparation of small lysates by using the enzyme lysostaphin to degrade the peptidoglycan layer. These lysates are prepared using a small patch of bacteria grown on LB agar plates, and the lysates can subsequently be used for PCR analyses.
Topics: Staphylococcus aureus; Lysostaphin; Polymerase Chain Reaction; Peptidoglycan; Cell Wall
PubMed: 37117023
DOI: 10.1101/pdb.prot107949 -
BioRxiv : the Preprint Server For... Apr 2024Cell growth in mycobacteria involves cell wall expansion that is restricted to the cell poles. The DivIVA homolog Wag31 is required for this process, but the molecular...
Cell growth in mycobacteria involves cell wall expansion that is restricted to the cell poles. The DivIVA homolog Wag31 is required for this process, but the molecular mechanism and protein partners of Wag31 have not been described. In this study of , we identify a connection between and trehalose monomycolate (TMM) transporter in a suppressor screen, and show that Wag31 and polar regulator PlrA are required for MmpL3's polar localization. In addition, the localization of PlrA and MmpL3 are responsive to nutrient and energy deprivation and inhibition of peptidoglycan metabolism. We show that inhibition of MmpL3 causes delocalized cell wall metabolism, but does not delocalize MmpL3 itself. We found that cells with an MmpL3 C-terminal truncation, which is defective for localization, have only minor defects in polar growth, but are impaired in their ability to downregulate cell wall metabolism under stress. Our work suggests that, in addition to its established function in TMM transport, MmpL3 has a second function in regulating global cell wall metabolism in response to stress. Our data are consistent with a model in which the presence of TMMs in the periplasm stimulates polar elongation, and in which the connection between Wag31, PlrA and the C-terminus of MmpL3 is involved in detecting and responding to stress in order to coordinate synthesis of the different layers of the mycobacterial cell wall in changing conditions.
PubMed: 38746181
DOI: 10.1101/2024.04.29.591792