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[ASAP] Chemically Modified Bacterial Sacculi as a Vaccine Microparticle Scaffold
Types and functions of heterogeneity in mycobacteria
Nature Reviews Microbiology, Published online: 01 April 2022; doi:10.1038/s41579-022-00721-0
In this Review, Aldridge and colleagues describe different types of mycobacterial heterogeneity and discuss how cell-to-cell heterogeneity and environmental heterogeneity are generated and regulated in response to environmental cues.[ASAP] Natural and Synthetic Sortase A Substrates Are Processed by Staphylococcus aureus via Different Pathways
Noelfeel like our lab should be cited in this...
[ASAP] Synthesis and Application of Rare Deoxy Amino l‑Sugar Analogues to Probe Glycans in Pathogenic Bacteria
Synthetic glycans control gut microbiome structure and mitigate colitis in mice
Nature Communications, Published online: 10 March 2022; doi:10.1038/s41467-022-28856-x
Here, the authors characterize the gut microbiome fermentation properties and therapeutic potential of chemically diverse synthetic glycans (SGs), showing they promote specific shifts in taxonomic and metabolite profiles, and exhibit therapeutic benefits in mouse models of colonic inflammation, together implying SGs as a potential avenue to treat disease by modulating the composition and metabolites produced by the gut microbiome.Small proline-rich proteins (SPRRs) are epidermally produced antimicrobial proteins that defend the cutaneous barrier by direct bacterial membrane disruption
Elife. 2022 Mar 2;11:e76729. doi: 10.7554/eLife.76729. Online ahead of print.
ABSTRACT
Human skin functions as a physical barrier, preventing the entry of foreign pathogens while also accommodating a myriad of commensal microorganisms. A key contributor to the skin landscape is the sebaceous gland. Mice devoid of sebocytes are prone to skin infection, yet our understanding of how sebocytes function in host defense is incomplete. Here we show that the small proline-rich proteins, SPRR1 and SPRR2 are bactericidal in skin. SPRR1B and SPPR2A were induced in human sebocytes by exposure to the bacterial cell wall component lipopolysaccharide (LPS). Colonization of germ-free mice was insufficient to trigger increased SPRR expression in mouse skin, but LPS injected into mouse skin triggered the expression of the mouse SPRR orthologous genes, Sprr1a and Sprr2a, through stimulation of MYD88. Both mouse and human SPRR proteins displayed potent bactericidal activity against MRSA (methicillin-resistant Staphylococcus aureus), Pseudomonas aeruginosa and skin commensals. Thus, Sprr1a-/-;Sprr2a-/- mice are more susceptible to MRSA and Pseudomonas aeruginosa skin infection. Lastly, mechanistic studies demonstrate that SPRR proteins exert their bactericidal activity through binding and disruption of the bacterial membrane. Taken together, these findings provide insight into the regulation and antimicrobial function of SPRR proteins in skin and how the skin defends the host against systemic infection.
PMID:35234613 | DOI:10.7554/eLife.76729
The AmiC/NlpD Pathway Dominates Peptidoglycan Breakdown in Neisseria meningitidis and Affects Cell Separation, NOD1 Agonist Production, and Infection
Infect Immun. 2022 Mar 17;90(3):e0048521. doi: 10.1128/IAI.00485-21. Epub 2022 Feb 14.
ABSTRACT
The human-restricted pathogen Neisseria meningitidis, which is best known for causing invasive meningococcal disease, has a nonpathogenic lifestyle as an asymptomatic colonizer of the human naso- and oropharyngeal space. N. meningitidis releases small peptidoglycan (PG) fragments during growth. It was demonstrated previously that N. meningitidis releases low levels of tripeptide PG monomer, which is an inflammatory molecule recognized by the human intracellular innate immune receptor NOD1. In the present study, we demonstrated that N. meningitidis released more PG-derived peptides than PG monomers. Using a reporter cell line overexpressing human NOD1, we showed that N. meningitidis activates NOD1 using PG-derived peptides. The generation of such peptides required the presence of the periplasmic N-acetylmuramyl-l-alanine amidase AmiC and the outer membrane lipoprotein NlpD. AmiC and NlpD were found to function in cell separation, and mutation of either amiC or nlpD resulted in large clumps of unseparated N. meningitidis cells instead of the characteristic diplococci. Using stochastic optical reconstruction microscopy, we demonstrated that FLAG epitope-tagged NlpD localized to the septum, while similarly tagged AmiC was found at the septum in some diplococci but was distributed around the cell in most cases. In a human whole-blood infection assay, an nlpD mutant was severely attenuated and showed particular sensitivity to complement. Thus, in N. meningitidis, the cell separation proteins AmiC and NlpD are necessary for NOD1 stimulation and survival during infection of human blood.
PMID:35225652 | PMC:PMC8929373 | DOI:10.1128/IAI.00485-21
[ASAP] Engineering Antibodies Targeting p16 MHC-Peptide Complexes
Structure and assembly of the S-layer in C. difficile
Nature Communications, Published online: 25 February 2022; doi:10.1038/s41467-022-28196-w
The S-layer is a two-dimensional protein array that covers the cell surface of many bacteria and archaea. Here, the authors use high-resolution X-ray crystallography and electron microscopy to provide detailed insights into S-layer organisation and assembly for the bacterial pathogen Clostridioides difficile.Selective Display of a Chemoattractant Agonist on Cancer Cells Activates the Formyl Peptide Receptor 1 on Immune Cells**
Bifunctional immune-engaging agents that exploit the inherent acidic microenvironment of most solid tumors were developed to selectively graft the surface of cancer cells with a formyl peptide receptor ligand (FPRL). We established that selectively remodeling cancer cells with such peptides activates formyl peptide receptors on recruited immune cells, potentially initiating an immune response towards tumors.
Abstract
Current immunotherapeutics often work by directing components of the immune system to recognize biomarkers on the surface of cancer cells to generate an immune response. However, variable changes in biomarker distribution and expression can result in inconsistent patient response. The development of a more universal tumor-homing strategy has the potential to improve selectivity and extend therapy to cancers with decreased expression or absence of specific biomarkers. Here, we designed a bifunctional agent that exploits the inherent acidic microenvironment of most solid tumors to selectively graft the surface of cancer cells with a formyl peptide receptor ligand (FPRL). Our approach is based on the pH(Low) insertion peptide (pHLIP), a unique peptide that selectively targets tumors in vivo by anchoring to cancer cells in a pH-dependent manner. We establish that selectively remodeling cancer cells with a pHLIP-based FPRL activates formyl peptide receptors on recruited immune cells, potentially initiating an immune response towards tumors.
[ASAP] Discovery of Inhibitors of the Lipopolysaccharide Transporter MsbA: From a Screening Hit to Potent Wild-Type Gram-Negative Activity
[ASAP] Chemoenzymatic Labeling Pathogens Containing Terminal N‑Acetylneuraminic Acid−α(2–3)-Galactose Glycans
[ASAP] Implications of Mycobacterium tuberculosis Metabolic Adaptability on Drug Discovery and Development
A gut-derived metabolite alters brain activity and anxiety behaviour in mice
Nature, Published online: 14 February 2022; doi:10.1038/s41586-022-04396-8
The gut-derived molecule 4-ethylphenol influences complex behaviours in mice through effects on oligodendrocyte function and myelin patterning in the brain.[ASAP] Site-Specific Protein Ubiquitylation Using an Engineered, Chimeric E1 Activating Enzyme and E2 SUMO Conjugating Enzyme Ubc9
[ASAP] Detailed Characterization of Antipathogenic Properties of Human Milk N-Glycome, against Staphylococcus aureus, Indicating Its Targeting on Cell Surface Proteins
NamZ1 and NamZ2 from the oral pathogen Tannerella forsythia are peptidoglycan processing exo-beta-N-acetylmuramidases with distinct substrate specificity
J Bacteriol. 2022 Feb 7:jb0059721. doi: 10.1128/jb.00597-21. Online ahead of print.
ABSTRACT
The Gram-negative periodontal pathogen Tannerella forsythia is inherently auxotrophic for N-acetylmuramic acid (MurNAc), which is an essential carbohydrate constituent of the peptidoglycan (PGN) of the bacterial cell wall. Thus, to build up its cell wall, T. forsythia strictly depends on the salvage of exogenous MurNAc or sources of MurNAc, such as polymeric or fragmentary PGN, derived from cohabiting bacteria within the oral microbiome. In our effort to elucidate how T. forsythia satisfies its demand for MurNAc, we recognized that the organism possesses three putative orthologs of the exo-β-N-acetylmuramidase BsNamZ from Bacillus subtilis, which cleaves non-reducing end, terminal MurNAc entities from the artificial substrate pNP-MurNAc and the naturally-occurring disaccharide substrate MurNAc-N-acetylglucosamine (GlcNAc). TfNamZ1 and TfNamZ2 were successfully purified as soluble, pure recombinant His6-fusions and characterized as exo-lytic β-N-acetylmuramidases with distinct substrate specificities. The activity of TfNamZ1 was considerably lower compared to TfNamZ2 and BsNamZ, in the cleavage of MurNAc-GlcNAc. When peptide-free PGN glycans were used as substrates, we revealed striking differences in the specificity and mode of action of these enzymes, as analyzed by mass spectrometry. TfNamZ1, but not TfNamZ2 or BsNamZ, released GlcNAc-MurNAc disaccharides from these glycans. In addition, glucosamine (GlcN)-MurNAc disaccharides were generated when partially N-deacetylated PGN glycans from B. subtilis 168 were applied. This characterizes TfNamZ1 as a unique disaccharide-forming exo-lytic β-N-acetylmuramidase (exo-disaccharidase), and, TfNamZ2 and BsNamZ as sole MurNAc monosaccharide-lytic exo-β-N-acetylmuramidases. IMPORTANCE Two exo-N-acetylmuramidases from T. forsythia belonging to glycosidase family GH171 (www.cazy.org) were shown to differ in their activities, thus revealing a functional diversity within this family: NamZ1 releases disaccharides (GlcNAc-MurNAc/GlcN-MurNAc) from the non-reducing ends of PGN glycans, whereas NamZ2 releases terminal MurNAc monosaccharides. This work provides a better understanding of how T. forsythia may acquire the essential growth factor MurNAc by the salvage of PGN from cohabiting bacteria in the oral microbiome, which may pave avenues for the development of anti-periodontal drugs. On a broad scale, our study indicates that the utilization of PGN as a nutrient source, involving exo-lytic N-acetylmuramidases with different modes of action, appears to be a general feature of bacteria, particularly among the phylum Bacteroidetes.
PMID:35129368 | DOI:10.1128/jb.00597-21
[ASAP] Discovery of a Tricyclic β‑Lactam as a Potent Antimicrobial Agent against Carbapenem-Resistant Enterobacterales, Including Strains with Reduced Membrane Permeability and Four-Amino Acid Insertion into Penicillin-Binding Protein 3: Structure–Activity-Relationships and In Vitro and In Vivo Activities
[ASAP] Quaternary Phosphonium Compounds: An Examination of Non-Nitrogenous Cationic Amphiphiles That Evade Disinfectant Resistance
Bacterial developmental checkpoint that directly monitors cell surface morphogenesis
NoelLYSM - LIPID II
Dev Cell. 2022 Feb 7;57(3):344-360.e6. doi: 10.1016/j.devcel.2021.12.021. Epub 2022 Jan 21.
ABSTRACT
Bacillus subtilis spores are encased in two concentric shells: an outer proteinaceous "coat" and an inner peptidoglycan "cortex," separated by a membrane. Cortex assembly depends on coat assembly initiation, but how cells achieve this coordination across the membrane is unclear. Here, we report that the protein SpoVID monitors the polymerization state of the coat basement layer via an extension to a functional intracellular LysM domain that arrests sporulation when coat assembly is initiated improperly. Whereas extracellular LysM domains bind mature peptidoglycan, SpoVID LysM binds to the membrane-bound lipid II peptidoglycan precursor. We propose that improper coat assembly exposes the SpoVID LysM domain, which then sequesters lipid II and prevents cortex assembly. SpoVID defines a widespread group of firmicute proteins with a characteristic N-terminal domain and C-terminal peptidoglycan-binding domains that might combine coat and cortex assembly roles to mediate a developmental checkpoint linking the morphogenesis of two spatially separated supramolecular structures.
PMID:35065768 | DOI:10.1016/j.devcel.2021.12.021
Resolving the conflict between antibiotic production and rapid growth by recognition of peptidoglycan of susceptible competitors
Nat Commun. 2022 Jan 20;13(1):431. doi: 10.1038/s41467-021-27904-2.
ABSTRACT
Microbial communities employ a variety of complex strategies to compete successfully against competitors sharing their niche, with antibiotic production being a common strategy of aggression. Here, by systematic evaluation of four non-ribosomal peptides/polyketide (NRPs/PKS) antibiotics produced by Bacillus subtilis clade, we revealed that they acted synergistically to effectively eliminate phylogenetically distinct competitors. The production of these antibiotics came with a fitness cost manifested in growth inhibition, rendering their synthesis uneconomical when growing in proximity to a phylogenetically close species, carrying resistance against the same antibiotics. To resolve this conflict and ease the fitness cost, antibiotic production was only induced by the presence of a peptidoglycan cue from a sensitive competitor, a response mediated by the global regulator of cellular competence, ComA. These results experimentally demonstrate a general ecological concept - closely related communities are favoured during competition, due to compatibility in attack and defence mechanisms.
PMID:35058430 | PMC:PMC8776889 | DOI:10.1038/s41467-021-27904-2
Architects of their own environment: How membrane proteins shape the Gram-negative cell envelope
Adv Protein Chem Struct Biol. 2022;128:1-34. doi: 10.1016/bs.apcsb.2021.10.001. Epub 2021 Nov 26.
ABSTRACT
Gram-negative bacteria are surrounded by a complex multilayered cell envelope, consisting of an inner and an outer membrane, and separated by the aqueous periplasm, which contains a thin peptidoglycan cell wall. These bacteria employ an arsenal of highly specialized membrane protein machineries to ensure the correct assembly and maintenance of the membranes forming the cell envelope. Here, we review the diverse protein systems, which perform these functions in Escherichia coli, such as the folding and insertion of membrane proteins, the transport of lipoproteins and lipopolysaccharide within the cell envelope, the targeting of phospholipids, and the regulation of mistargeted envelope components. Some of these protein machineries have been known for a long time, yet still hold surprises. Others have only recently been described and some are still missing pieces or yet remain to be discovered.
PMID:35034716 | DOI:10.1016/bs.apcsb.2021.10.001
Checkpoints That Regulate Balanced Biosynthesis of Lipopolysaccharide and Its Essentiality in Escherichia coli
Int J Mol Sci. 2021 Dec 24;23(1):189. doi: 10.3390/ijms23010189.
ABSTRACT
The outer membrane (OM) of Gram-negative bacteria, such as Escherichia coli, is essential for their viability. Lipopolysaccharide (LPS) constitutes the major component of OM, providing the permeability barrier, and a tight balance exists between LPS and phospholipids amounts as both of these essential components use a common metabolic precursor. Hence, checkpoints are in place, right from the regulation of the first committed step in LPS biosynthesis mediated by LpxC through its turnover by FtsH and HslUV proteases in coordination with LPS assembly factors LapB and LapC. After the synthesis of LPS on the inner leaflet of the inner membrane (IM), LPS is flipped by the IM-located essential ATP-dependent transporter to the periplasmic face of IM, where it is picked up by the LPS transport complex spanning all three components of the cell envelope for its delivery to OM. MsbA exerts its intrinsic hydrocarbon ruler function as another checkpoint to transport hexa-acylated LPS as compared to underacylated LPS. Additional checkpoints in LPS assembly are: LapB-assisted coupling of LPS synthesis and translocation; cardiolipin presence when LPS is underacylated; the recruitment of RfaH transcriptional factor ensuring the transcription of LPS core biosynthetic genes; and the regulated incorporation of non-stoichiometric modifications, controlled by the stress-responsive RpoE sigma factor, small RNAs and two-component systems.
PMID:35008618 | PMC:PMC8745692 | DOI:10.3390/ijms23010189
The Role of the Gut Microbiota in the Pathogenesis of Diabetes
Int J Mol Sci. 2022 Jan 1;23(1):480. doi: 10.3390/ijms23010480.
ABSTRACT
Diabetes mellitus is a significant clinical and therapeutic problem because it can lead to serious long-term complications. Its pathogenesis is not fully understood, but there are indications that dysbiosis can play a role in the development of diabetes, or that it appears during the course of the disease. Changes in microbiota composition are observed in both type 1 diabetes (T1D) and type 2 diabetes (T2D) patients. These modifications are associated with pro-inflammation, increased intestinal permeability, endotoxemia, impaired β-cell function and development of insulin resistance. This review summarizes the role of the gut microbiota in healthy individuals and the changes in bacterial composition that can be associated with T1D or T2D. It also presents new developments in diabetes therapy based on influencing the gut microbiota as a promising method to alter the course of diabetes. Moreover, it highlights the lacking data and suggests future directions needed to prove the causal relationship between dysbiosis and diabetes, both T1D and T2D.
PMID:35008906 | PMC:PMC8745411 | DOI:10.3390/ijms23010480
[ASAP] Chemoproteomic Analysis of Microbiota Metabolite–Protein Targets and Mechanisms
Microbiome-based therapeutics
Nature Reviews Microbiology, Published online: 06 January 2022; doi:10.1038/s41579-021-00667-9
Microbiome-based therapeutics hold great promise for reducing disease susceptibility and enhancing disease resistance. In this Review, Sorbara and Pamer explore the major bacterial phyla associated with health benefits and the potential of microbiome-based therapeutics, including faecal microbiota transplantation, bacterial consortia, engineered symbiotic bacteria, diet and prebiotics, and microbiome-derived proteins and metabolites. They also discuss the challenges confronting therapeutic development as well as the regulatory hurdles for clinical trials and manufacturing.LcpB Is a Pyrophosphatase Responsible for Wall Teichoic Acid Synthesis and Virulence in Staphylococcus aureus Clinical Isolate ST59
Front Microbiol. 2021 Dec 16;12:788500. doi: 10.3389/fmicb.2021.788500. eCollection 2021.
ABSTRACT
The community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) causes severe pandemics primarily consisting of skin and soft tissue infections. However, the underlying pathomechanisms of the bacterium are yet to fully understood. The present study identifies LcpB protein, which belongs to the LytR-A-Psr (LCP) family, is crucial for cell wall synthesis and virulence in S. aureus. The findings revealed that LcpB is a pyrophosphatase responsible for wall teichoic acid synthesis. The results also showed that LcpB regulates enzyme activity through specific key arginine sites in its LCP domain. Furthermore, knockout of lcpB in the CA-MRSA isolate ST59 resulted in enhanced hemolytic activity, enlarged of abscesses, and increased leukocyte infiltration. Meanwhile, we also found that LcpB regulates virulence in agr-independent manner and the key sites for pyrophosphatase of LcpB play critical roles in regulating the virulence. In addition, the results showed that the role of LcpB was different between methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). This study therefore highlights the dual role of LcpB in cell wall synthesis and regulation of virulence. These insights on the underlying molecular mechanisms can thus guide the development of novel anti-infective strategies.
PMID:34975809 | PMC:PMC8716876 | DOI:10.3389/fmicb.2021.788500
Synthesis and Evaluation of Diverse N-Substituted Disaccharide Dipeptides for Human NOD2 Stimulation Activity
Chem Asian J. 2021 Dec 23:e202101169. doi: 10.1002/asia.202101169. Online ahead of print.
ABSTRACT
A new strategy for the preparation of distinct N-substituted muropeptides is described. Different orthogonally N-protected disaccharide thioglycosides were designed and synthesized. Among them, compound 4, qualified as a key intermediate, was utilized for further chemical transformations to develop a series of diverse N-substituted-glucosaminyl N-substituted-muramyl dipeptides (GMDPs). These unique muropeptides were applied for the study of human NOD2 stimulation. Intriguingly, structural modification of the MurNAc residue to N-non-substituted muramic acid (MurNH2 ) in GMDP dramatically impaired NOD2 stimulatory activity, but GMDPs possessing the glucosamine residue with a free amino group retained NOD2 stimulation activity. This work is the first study to illustrate the impact of both N-substituents of GMDPs on immunostimulatory activities of human NOD2.
PMID:34951523 | DOI:10.1002/asia.202101169
[ASAP] Morphological Characterization of Antibiotic Combinations
Virulence factors perforate the pathogen-containing vacuole to signal efferocytosis
Publication date: 9 February 2022
Source: Cell Host & Microbe, Volume 30, Issue 2
Author(s): Hirotaka Hiyoshi, Bevin C. English, Vladimir E. Diaz-Ochoa, Tamding Wangdi, Lillian F. Zhang, Miako Sakaguchi, Takeshi Haneda, Renée M. Tsolis, Andreas J. Bäumler