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Heliyon Mar 2024Contemporary research in the field of microbiota shows that commensal bacteria influence physiological activity of different organs and systems of a human organism, such... (Review)
Review
Contemporary research in the field of microbiota shows that commensal bacteria influence physiological activity of different organs and systems of a human organism, such as brain, lungs, immune and metabolic systems. This influence is realized by various processes. One of them is trough modulation of immune mechanisms. Interactions between microbiota and the human immune system are known to be complex and ambiguous. Dendritic cells (DCs) are unique cells, which initiate the development and polarization of adaptive immune response. These cells also interconnect native and specific immune reactivity. A large set of biochemical signals from microbiota in the form of different microbiota associated molecular patterns (MAMPs) and bacterial metabolites that act locally and distantly in the human organism. As a result, commensal bacteria influence the maturity and activity of dendritic cells and affect the overall immune reactivity of the human organism. It then determines the response to pathogenic microorganisms, inflammation, associated with different pathological conditions and even affects the effectiveness of vaccination.
PubMed: 38444507
DOI: 10.1016/j.heliyon.2024.e27125 -
Frontiers in Cellular and Infection... 2023Extracellular vesicles (EVs) are nano-sized particles released from cells into the extracellular environment, and are separated from eukaryotic cells, bacteria, and... (Review)
Review
Extracellular vesicles (EVs) are nano-sized particles released from cells into the extracellular environment, and are separated from eukaryotic cells, bacteria, and other organisms with cellular structures. EVs alter cell communication by delivering their contents and performing various functions depending on their cargo and release into certain environments or other cells. The cell walls of Gram-positive bacteria have a thick peptidoglycan layer and were previously thought to be unable to produce EVs. However, recent studies have demonstrated that Gram-positive bacterial EVs are crucial for health and disease. In this review, we have summarized the formation, composition, and characteristics of the contents, resistance to external stress, participation in immune regulation, and other functions of Gram-positive bacterial EVs, as well as their application in clinical diagnosis and treatment, to provide a new perspective to further our understanding of Gram-positive bacterial EVs.
Topics: Gram-Positive Bacteria; Bacteria; Membranes; Extracellular Vesicles
PubMed: 37860067
DOI: 10.3389/fcimb.2023.1273813 -
Communications Biology Sep 2023Cell shape is genetically inherited by all forms of life. Some unicellular microbes increase niche adaptation altering shape whereas most show invariant morphology. A...
Cell shape is genetically inherited by all forms of life. Some unicellular microbes increase niche adaptation altering shape whereas most show invariant morphology. A universal system of peptidoglycan synthases guided by cytoskeletal scaffolds defines bacterial shape. In rod-shaped bacteria, this system consists of two supramolecular complexes, the elongasome and divisome, which insert cell wall material along major and minor axes. Microbes with invariant shape are thought to use a single morphogenetic system irrespective of the occupied niche. Here, we provide evidence for two elongasomes that generate (rod) shape in the same bacterium. This phenomenon was unveiled in Salmonella, a pathogen that switches between extra- and intracellular lifestyles. The two elongasomes can be purified independently, respond to different environmental cues, and are directed by distinct peptidoglycan synthases: the canonical PBP2 and the pathogen-specific homologue PBP2. The PBP2-elongasome responds to neutral pH whereas that directed by PBP2 assembles in acidic conditions. Moreover, the PBP2-elongasome moves at a lower speed. Besides Salmonella, other human, animal, and plant pathogens encode alternative PBPs with predicted morphogenetic functions. Therefore, contrasting the view of morphological plasticity facilitating niche adaptation, some pathogens may have acquired alternative systems to preserve their shape in the host.
Topics: Animals; Humans; Peptidoglycan; Salmonella; Acclimatization; Cell Shape; Cell Wall
PubMed: 37689828
DOI: 10.1038/s42003-023-05308-w -
BioRxiv : the Preprint Server For... Aug 2023Active nutrient uptake is fundamental for survival and pathogenicity of Gram-negative bacteria, which operate a multi-protein Ton system to transport essential nutrients...
Active nutrient uptake is fundamental for survival and pathogenicity of Gram-negative bacteria, which operate a multi-protein Ton system to transport essential nutrients like metals and vitamins. This system harnesses the proton motive force at the inner membrane to energize the import through the outer membrane, but the mechanism of energy transfer remains enigmatic. Here, we study the periplasmic domain of ExbD, a crucial component of the proton channel of the Ton system. We show that this domain is a dynamic dimer switching between two conformations representing the proton channel's open and closed states. By phenotypic assays we demonstrate that this conformational switch is essential for the nutrient uptake by bacteria. The open state of ExbD triggers a disorder to order transition of TonB, enabling TonB to supply energy to the nutrient transporter. We also reveal the anchoring role of the peptidoglycan layer in this mechanism. Herein, we propose a mechanistic model for the Ton system, emphasizing ExbD duality and the pivotal catalytic role of peptidoglycan. Sequence analysis suggests that this mechanism is conserved in other systems energizing gliding motility and membrane integrity. Our study fills important gaps in understanding bacterial motor mechanism and proposes novel antibacterial strategies.
PubMed: 37609138
DOI: 10.1101/2023.08.11.552980 -
Protein & Cell Oct 2023Interactions between gut microbiome and host immune system are fundamental to maintaining the intestinal mucosal barrier and homeostasis. At the host-gut microbiome... (Review)
Review
Interactions between gut microbiome and host immune system are fundamental to maintaining the intestinal mucosal barrier and homeostasis. At the host-gut microbiome interface, cell wall-derived molecules from gut commensal bacteria have been reported to play a pivotal role in training and remodeling host immune responses. In this article, we review gut bacterial cell wall-derived molecules with characterized chemical structures, including peptidoglycan and lipid-related molecules that impact host health and disease processes via regulating innate and adaptive immunity. Also, we aim to discuss the structures, immune responses, and underlying mechanisms of these immunogenic molecules. Based on current advances, we propose cell wall-derived components as important sources of medicinal agents for the treatment of infection and immune diseases.
Topics: Gastrointestinal Microbiome; Intestinal Mucosa; Bacteria; Immune System; Symbiosis; Immunity, Mucosal; Immunity, Innate
PubMed: 37013853
DOI: 10.1093/procel/pwad016 -
Food Science & Nutrition Aug 2023Functional foods are gaining significant research attention of researchers due to their health-endorsing properties due to their bioactive components either living cells... (Review)
Review
Functional foods are gaining significant research attention of researchers due to their health-endorsing properties due to their bioactive components either living cells (probiotics) or nonviable cells (prebiotics). The term "postbiotic" specifies the soluble substances, such as enzymes, peptides, teichoic acids, muropeptides derived from peptidoglycans, polysaccharides, cell surface proteins, and organic acids, that are secreted by living bacteria or released after bacterial lysis. Due to various signaling molecules which may have antioxidant, immunomodulatory, antiinflammatory, antihypertensive, and antiproliferative activities, postbiotics offer great potential to be used in pharmaceutical, food, and nutraceutical industries, to promote health and ailment prevention. This recent review is a landmark of information relevant to the production of postbiotics along with salient features to use in various fields ranging from food to immunomodulation and selective and effective therapy. It also puts forward the concept that postbiotics are way more effective than probiotics in the veterinary, food as well as medical field which ultimately helps in reducing the disease burden along with human health.
PubMed: 37576043
DOI: 10.1002/fsn3.3465 -
Probiotics and Antimicrobial Proteins Apr 2024Di-(2-ethylhexyl) phthalate (DEHP) is the widely detected plasticizer in foods whose exposure is associated with a myriad of human disorders. The present study focused...
Di-(2-ethylhexyl) phthalate (DEHP) is the widely detected plasticizer in foods whose exposure is associated with a myriad of human disorders. The present study focused on identifying Lactobacillus strains with high adsorption potential towards DEHP and further elucidating the mechanism of binding using HPLC, FTIR and SEM. Two strains, Lactobacillus rhamnosus GG and Lactobacillus plantarum MTCC 25,433, were found to rapidly adsorb more than 85% of DEHP in 2 h. Binding potential remained unaffected by heat treatment. Moreover, acid pre-treatment enhanced the DEHP adsorption. Chemical pre-treatments, such as NaIO, pronase E or lipase, caused reduction in DEHP adsorption to 46% (LGG), 49% (MTCC 25,433) and 62% (MTCC 25,433), respectively, attributing it to cell wall polysaccharides, proteins and lipids. This was also corroborated by stretching vibrations of C = O, N-H, C-N and C-O functional groups. Furthermore, SDS and urea pre-treatment, demonstrated the crucial role of hydrophobic interactions in DEHP adsorption. The extracted peptidoglycan from LGG and MTCC 25,433 adsorbed 45% and 68% of DEHP, respectively, revealing the imperative role of peptidoglycan and its integrity in DEHP adsorption. These findings indicated that DEHP removal was based on physico-chemical adsorption and cell wall proteins, polysaccharides or peptidoglycan played a primary role in its adsorption. Owing to the high binding efficiency, L. rhamnosus GG and L. plantarum MTCC 25,433 were considered to be a potential detoxification strategy to mitigate the risk associated with the consumption of DEHP-contaminated foods.
Topics: Humans; Diethylhexyl Phthalate; Lactobacillus; Adsorption; Peptidoglycan; Phthalic Acids
PubMed: 36995550
DOI: 10.1007/s12602-023-10055-9 -
Cell Reports Aug 2023The success of Mycobacterium tuberculosis (Mtb) is largely attributed to its ability to physiologically adapt and withstand diverse localized stresses within host...
The success of Mycobacterium tuberculosis (Mtb) is largely attributed to its ability to physiologically adapt and withstand diverse localized stresses within host microenvironments. Here, we present a data-driven model (EGRIN 2.0) that captures the dynamic interplay of environmental cues and genome-encoded regulatory programs in Mtb. Analysis of EGRIN 2.0 shows how modulation of the MtrAB two-component signaling system tunes Mtb growth in response to related host microenvironmental cues. Disruption of MtrAB by tunable CRISPR interference confirms that the signaling system regulates multiple peptidoglycan hydrolases, among other targets, that are important for cell division. Further, MtrA decreases the effectiveness of antibiotics by mechanisms of both intrinsic resistance and drug tolerance. Together, the model-enabled dissection of complex MtrA regulation highlights its importance as a drug target and illustrates how EGRIN 2.0 facilitates discovery and mechanistic characterization of Mtb adaptation to specific host microenvironments within the host.
Topics: Transcription Factors; Mycobacterium tuberculosis; Bacterial Proteins; Cell Division; Drug Tolerance
PubMed: 37542718
DOI: 10.1016/j.celrep.2023.112875 -
Natural Product Reports Nov 2023Covering: the literature up to 2022This study discusses various synthetic strategies for the synthesis of lipid II, the pivotal bacterial cell wall precursor. In detail,... (Review)
Review
Covering: the literature up to 2022This study discusses various synthetic strategies for the synthesis of lipid II, the pivotal bacterial cell wall precursor. In detail, it examines different solution phase approaches, reviews various solid phase sequences, and evaluates enzymatic ventures. The underlying rationale, scope, limitations, and perspectives of these strategies are discussed. The focus is on the tactics and strategies towards the authentic peptidoglycan compound, as well as analogues thereof with shortened side chains, which are increasingly recognized as more beneficial surrogates with more favorable physicochemical properties.
Topics: Bacteria; Peptidoglycan; Cell Wall
PubMed: 37492928
DOI: 10.1039/d3np00018d -
Frontiers in Microbiology 2023Foodborne diseases are caused by food contaminated by pathogenic bacteria such as and a critical threat to human health. As a novel antibacterial agent against... (Review)
Review
A comprehensive review of the applications of bacteriophage-derived endolysins for foodborne bacterial pathogens and food safety: recent advances, challenges, and future perspective.
Foodborne diseases are caused by food contaminated by pathogenic bacteria such as and a critical threat to human health. As a novel antibacterial agent against foodborne pathogens, endolysins are peptidoglycan hydrolases encoded by bacteriophages that lyse bacterial cells by targeting their cell wall, notably in Gram-positive bacteria due to their naturally exposed peptidoglycan layer. These lytic enzymes have gained scientists' interest in recent years due to their selectivity, mode of action, engineering potential, and lack of resistance mechanisms. The use of endolysins for food safety has undergone significant improvements, which are summarized and discussed in this review. Endolysins can remove bacterial biofilms of foodborne pathogens and their cell wall-binding domain can be employed as a tool for quick detection of foodborne pathogens. We explained the applications of endolysin for eliminating pathogenic bacteria in livestock and various food matrices, as well as the limitations and challenges in use as a dietary supplement. We also highlight the novel techniques of the development of engineering endolysin for targeting Gram-negative bacterial pathogens. In conclusion, endolysin is safe and effective against foodborne pathogens and has no adverse effect on human cells and beneficial microbiota. As a result, endolysin could be employed as a functional bio-preservative agent to improve food stability and safety and maintain the natural taste of food quality.
PubMed: 37869651
DOI: 10.3389/fmicb.2023.1259210