A Broad Spectrum Lasso Peptide Antibiotic Targeting the Bacterial Ribosome.

Lasso peptides, biologically active molecules with a distinct structurally constrained knotted fold, are natural products belonging to the class of ribosomally-synthesized and posttranslationally modified peptides (RiPPs). Lasso peptides act upon several bacterial targets, but none have been reported to inhibit the ribosome, one of the main antibiotic targets in the bacterial cell. Here, we report the identification and characterization of the lasso peptide antibiotic, lariocidin (LAR), and its internally cyclized derivative, lariocidin B (LAR-B), produced by .

A Nanocomposite Dynamic Covalent Cross-Linked Hydrogel Loaded with Fusidic Acid for Treating Antibiotic-Resistant Infected Wounds.

Methicillin-resistant (MRSA) is associated with high levels of morbidity and is considered a difficult-to-treat infection, often requiring nonstandard treatment regimens and antibiotics. Since over 40% of the emerging antibiotic compounds have insufficient solubility that limits their bioavailability and thus efficacy through oral or intravenous administration, it is crucial that alternative drug delivery products be developed for wound care applications. Existing effective treatments for soft tissue MRSA infections, such as fusidic acid (FA), which is typically administered orally, could also benefit from alternative routes of administration to improve local efficacy and bioavailability while reducing the required therapeutic dose.

Synthetic Biology Facilitates Semisynthetic Development of Type V Glycopeptide Antibiotics Targeting Vancomycin-Resistant .

The continued efficacy of glycopeptide antibiotics (GPAs) against Gram-positive bacteria is challenged by the emergence and spread of GPA-resistant pathogens, particularly vancomycin-resistant enterococci (VRE). The growing frequency of GPA resistance propels the need for innovative development of more effective antibiotics. Unlike canonical GPAs like vancomycin, Type V GPAs adopt a distinct mode of action by binding peptidoglycan and blocking the activity of autolysins essential for cell division, rendering them a promising class of antibiotics for further development.

Deep learning-guided discovery of an antibiotic targeting Acinetobacter baumannii.

Acinetobacter baumannii is a nosocomial Gram-negative pathogen that often displays multidrug resistance. Discovering new antibiotics against A. baumannii has proven challenging through conventional screening approaches.

Characterizing the Pathogenic Potential of Crohn's Disease-Associated Adherent-Invasive .

The microbiome of Crohn's disease (CD) patients is composed of a microbial community that is considered dysbiotic and proinflammatory in nature. The overrepresentation of species is a common feature of the CD microbiome, and much attention has been given to understanding the pathogenic role this feature plays in disease activity. Over 2 decades ago, a new subtype called adherent-invasive (AIEC) was isolated and linked to ileal Crohn's disease.

Distinct Molecular Features of NleG Type 3 Secreted Effectors Allow for Different Roles during Citrobacter rodentium Infection in Mice.

The NleGs are the largest family of type 3 secreted effectors in attaching and effacing (A/E) pathogens, such as enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli, and Citrobacter rodentium. NleG effectors contain a conserved C-terminal U-box domain acting as a ubiquitin protein ligase and target host proteins via a variable N-terminal portion.

Genetic and Chemical Screening Reveals Targets and Compounds to Potentiate Gram-Positive Antibiotics against Gram-Negative Bacteria.

Gram-negative bacteria are intrinsically resistant to a plethora of antibiotics that effectively inhibit the growth of Gram-positive bacteria. The intrinsic resistance of Gram-negative bacteria to classes of antibiotics, including rifamycins, aminocoumarins, macrolides, glycopeptides, and oxazolidinones, has largely been attributed to their lack of accumulation within cells due to poor permeability across the outer membrane, susceptibility to efflux pumps, or a combination of these factors. Due to the difficulty in discovering antibiotics that can bypass these barriers, finding targets and compounds that increase the activity of these ineffective antibiotics against Gram-negative bacteria has the potential to expand the antibiotic spectrum.

Psychological stress impairs IL22-driven protective gut mucosal immunity against colonising pathobionts.

Crohn's disease is an inflammatory disease of the gastrointestinal tract characterized by an aberrant response to microbial and environmental triggers. This includes an altered microbiome dominated by Enterobacteriaceae and in particular adherent-invasive E. coli (AIEC).

Low dietary fiber promotes enteric expansion of a Crohn's disease-associated pathobiont independent of obesity.

Obesity is associated with metabolic, immunological, and infectious disease comorbidities, including an increased risk of enteric infection and inflammatory bowel disease such as Crohn's disease (CD). Expansion of intestinal pathobionts such as adherent-invasive (AIEC) is a common dysbiotic feature of CD, which is amplified by prior use of oral antibiotics. Although high-fat, high-sugar diets are associated with dysbiotic expansion of , it is unknown if the content of fat or another dietary component in obesogenic diets is sufficient to promote AIEC expansion.

Emerging and divergent roles of pyrophosphorylated nucleotides in bacterial physiology and pathogenesis.

Bacteria inhabit diverse environmental niches and consequently must modulate their metabolism to adapt to stress. The nucleotide second messengers guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) (collectively referred to as (p)ppGpp) are essential for survival during nutrient starvation. (p)ppGpp is synthesized by the RelA-SpoT homologue (RSH) protein family and coordinates the control of cellular metabolism through its combined effect on over 50 proteins.

High-throughput fitness screening and transcriptomics identify a role for a type IV secretion system in the pathogenesis of Crohn's disease-associated Escherichia coli.

Adherent-invasive Escherichia coli (AIEC) are pathogenic bacteria frequently isolated from patients who have Crohn's disease (CD). Despite the phenotypic differences between AIEC and commensal E. coli, comparative genomic approaches have been unable to differentiate these two groups, making the identification of key virulence factors a challenge.

(p)ppGpp-Dependent Regulation of the Nucleotide Hydrolase PpnN Confers Complement Resistance in Salmonella enterica Serovar Typhimurium.

The stringent response is an essential mechanism of metabolic reprogramming during environmental stress that is mediated by the nucleotide alarmones guanosine tetraphosphate and pentaphosphate [(p)ppGpp]. In addition to physiological adaptations, (p)ppGpp also regulates virulence programs in pathogenic bacteria, including serovar Typhimurium. Typhimurium is a common cause of acute gastroenteritis, but it may also spread to systemic tissues, resulting in severe clinical outcomes.

High-Throughput Chemical Screening for Inhibitors of Pathogenicity Island 2.

Anti-virulence therapies are under active investigation as antibiotic alternatives; however, their identification from large-scale chemical libraries poses a unique challenge. The dispensability of virulence factors for growth precludes conventional, optical density-based screening methods. Here, we provide a protocol for high-throughput screening with a cell-based, promoter reporter platform.

Genetic and Chemical Screening in Human Blood Serum Reveals Unique Antibacterial Targets and Compounds against Klebsiella pneumoniae.

Antibiotics halt the growth of bacteria by targeting core, essential physiology that is required for life on standard microbiological media. Many more biochemical and virulence processes, however, are required for bacteria to cause infection in a host. Indeed, chemical inhibitors of the latter processes are overlooked using conventional antibiotic drug discovery approaches.

Targeting Two-Component Systems Uncovers a Small-Molecule Inhibitor of Salmonella Virulence.

Salmonella serovars are leading causes of gastrointestinal disease and have become increasingly resistant to fluoroquinolone and cephalosporin antibiotics. Overcoming this healthcare crisis requires new approaches in antibiotic discovery and the identification of unique bacterial targets. In this work, we describe a chemical genomics approach to identify inhibitors of Salmonella virulence.

Evolution-guided discovery of antibiotics that inhibit peptidoglycan remodelling.

Addressing the ongoing antibiotic crisis requires the discovery of compounds with novel mechanisms of action that are capable of treating drug-resistant infections. Many antibiotics are sourced from specialized metabolites produced by bacteria, particularly those of the Actinomycetes family. Although actinomycete extracts have traditionally been screened using activity-based platforms, this approach has become unfavourable owing to the frequent rediscovery of known compounds.

Mimicking the human environment in mice reveals that inhibiting biotin biosynthesis is effective against antibiotic-resistant pathogens.

To revitalize the antibiotic pipeline, it is critical to identify and validate new antimicrobial targets. In Mycobacteria tuberculosis and Francisella tularensis, biotin biosynthesis is a key fitness determinant during infection, making it a high-priority target. However, biotin biosynthesis has been overlooked for priority pathogens such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa.

Complete Genome Sequence of Citrobacter rodentium Strain DBS100.

strain DBS100 causes an infection of the intestines in mice. It provides an important model for human gastrointestinal pathogens, such as enteropathogenic and enterohemorrhagic , which cause life-threatening infections. To identify the genetic determinants that are common across the enteropathogenic bacteria, we sequenced the DBS100 genome.

The Unique Lifestyle of Crohn's Disease-Associated Adherent-Invasive Escherichia coli.

Escherichia coli is one of the most genetically and phenotypically diverse species of bacteria. This remarkable diversity produces a plethora of clinical outcomes following infection and has informed much of what we currently know about host-pathogen interactions for a wide range of bacteria-host relationships. In studying the role of microbes in disease, adherent-invasive E.

Duodenal bacterial proteolytic activity determines sensitivity to dietary antigen through protease-activated receptor-2.

Microbe-host interactions are generally homeostatic, but when dysfunctional, they can incite food sensitivities and chronic diseases. Celiac disease (CeD) is a food sensitivity characterized by a breakdown of oral tolerance to gluten proteins in genetically predisposed individuals, although the underlying mechanisms are incompletely understood. Here we show that duodenal biopsies from patients with active CeD have increased proteolytic activity against gluten substrates that correlates with increased Proteobacteria abundance, including Pseudomonas.

Endocytosis of commensal antigens by intestinal epithelial cells regulates mucosal T cell homeostasis.

Commensal bacteria influence host physiology, without invading host tissues. We show that proteins from segmented filamentous bacteria (SFB) are transferred into intestinal epithelial cells (IECs) through adhesion-directed endocytosis that is distinct from the clathrin-dependent endocytosis of invasive pathogens. This process transfers microbial cell wall-associated proteins, including an antigen that stimulates mucosal T helper 17 (T17) cell differentiation, into the cytosol of IECs in a cell division control protein 42 homolog (CDC42)-dependent manner.

The Role of the Host in Driving Phenotypic Heterogeneity in Salmonella.

The complex infection environment within hosts exerts unique stresses across tissues and cell types, selecting for phenotypic heterogeneity in bacterial populations. Pathogens maintain variability during infection as a strategy to cope with fluctuating host immune conditions, leading to diversification of virulence phenotypes. Recent improvements in single-cell analyses have revealed that distinct bacterial subpopulations contribute unique colonization and growth strategies across infection sites.