Mechanisms of tigecycline resistance in Gram-negative bacteria: A narrative review.

Tigecycline serves as a critical "final-resort" antibiotic for treating bacterial infections caused by multidrug-resistant bacteria for which treatment options are severely limited. The increasing prevalence of tigecycline resistance, particularly among Gram-negative bacteria, is a major concern. Various mechanisms have been identified as contributors to tigecycline resistance, including upregulation of nonspecific Resistance Nodulation Division (RND) efflux pumps due to mutations in transcriptional regulators, enzymatic modification of tigecycline by monooxygenase enzymes, and mutations affecting tigecycline binding sites.

Homophenylalanine-derived benzo[1,4]diazepine-2,5-diones are strong bacterial quorum sensing inhibitors.

Benzo[1,4]diazepines show a large diversity of biological activities and are still commonly used as medications against a broad range of diseases. Within our research in the field of chemo-enzymatic alkaloid synthesis, we developed a synthetic route towards close structural relatives, namely benzo[1,4]diazepine-2,5-diones. Possible antimicrobial activities of these substances are barely known up to date.

Olikomycin A-A Novel Calcium-Dependent Lipopeptide with Antibiotic Activity Against Multidrug-Resistant Bacteria.

Research into new antibiotics is becoming increasingly important as antibiotic resistance increases worldwide. The genus Streptomyces in particular is able to produce a wide range of antimicrobial products due to the large number of biosynthetic gene clusters (BGCs) in its genome. However, not all BGCs are expressed under laboratory conditions.

Studying Target-Engagement of Anti-Infectives by Solvent-Induced Protein Precipitation and Quantitative Mass Spectrometry.

Antimicrobial resistance (AMR) poses a serious threat to global health. The rapid emergence of resistance contrasts with the slow pace of antimicrobial development, emphasizing the urgent need for innovative drug discovery approaches. This study addresses a critical bottleneck in early drug development by introducing integral solvent-induced protein precipitation (iSPP) to rapidly assess the target-engagement of lead compounds in extracts of pathogenic microorganisms under close-to-physiological conditions.

The PLSDB 2025 update: enhanced annotations and improved functionality for comprehensive plasmid research.

Plasmids are extrachromosomal DNA molecules in bacteria and archaea, playing critical roles in horizontal gene transfer, antibiotic resistance, and pathogenicity. Since its first release in 2018, our database on plasmids, PLSDB, has significantly grown and enhanced its content and scope. From 34 513 records contained in the 2021 version, PLSDB now hosts 72 360 entries.

In Vivo Activity Profiling of Biosynthetic Darobactin D22 against Critical Gram-Negative Pathogens.

In recent years, naturally occurring darobactins have emerged as a promising compound class to combat infections caused by critical Gram-negative pathogens. In this study, we describe the in vivo evaluation of derivative D22, a non-natural biosynthetic darobactin analogue with significantly improved antibacterial activity. We found D22 to be active in vivo against key critical Gram-negative human pathogens, as demonstrated in murine models of thigh infection, peritonitis/sepsis, and urinary tract infection (UTI).

In vitro activity of ceftazidime-avibactam/aztreonam combination against MBL-producing Pseudomonas aeruginosa strains.

Purpose: The emergence of multidrug-resistant P. aeruginosa isolates poses a challenge to healthcare systems worldwide. Rising numbers in deaths, duration of hospitalization as well as failing treatments prove the hazards posed by these pathogens.

Chemical diversity of cyanobacterial natural products.

Covering: 2010 to 2023Cyanobacterial natural products are a diverse group of molecules with promising biotechnological applications. This review examines the chemical diversity of 995 cyanobacterial metabolites reported from 2010 to 2023. A computational analysis using similarity networking was applied to visualize the chemical space and to compare the diversity of cyanobacterial metabolites among taxonomic orders and environmental sources.

Thermo-amplifier circuit in probiotic E. coli for stringently temperature-controlled release of a novel antibiotic.

Peptide drugs have seen rapid advancement in biopharmaceutical development, with over 80 candidates approved globally. Despite their therapeutic potential, the clinical translation of peptide drugs is hampered by challenges in production yields and stability. Engineered bacterial therapeutics is a unique approach being explored to overcome these issues by using bacteria to produce and deliver therapeutic compounds at the body site of use.

Targeting the IspE Enzyme.

The enzyme IspE in is considered an attractive drug target, as it is essential for parasite survival and is absent in the human proteome. Yet it still has not been addressed by a small-molecule inhibitor. In this study, we conducted a high-throughput screening campaign against the IspE enzyme.

Total Synthesis and Configuration Assignment of (+)-Myxoquaterine-450.

Myxoquaterines represent a recently discovered class of natural products with intriguing biological properties. They were isolated from Pendulasporacea albinea MSr 11954 and display a unique structure combining heterocyclic (pyrrole, oxazoline), hexaene, and 2-amino-1,3-diol subunits. We have now synthesized the first example of a myxoquaterine natural product, myxoquaterine-450, in a highly convergent fashion, in which the sensitive hexaene unit was established in the final stages of the synthesis (16 linear steps starting from l-serine).

IspE kinase as an anti-infective target: Role of a hydrophobic pocket in inhibitor binding.

Enzymes of the methylerythritol phosphate (MEP) pathway are potential targets for antimicrobial drug discovery. Here, we focus on 4-diphosphocytidyl-2-C-methyl-D-erythritol (IspE) kinase from the MEP pathway. We use biochemical and structural biology methods to investigate homologs from pathogenic microorganisms; Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii.

Synthesis and antibiotic potential of myxocoumarin-inspired chromene dione analogs.

The rapid emergence of antibiotic resistance in recent years poses a substantial global health threat. Thus, the discovery of potent novel antibiotics is of utmost importance. One such compound class with promising antibiotic potential are the myxocoumarins from MYX-030, which exhibit exceptional antibiotic activities against several Gram-positive pathogens, including MRSA.

Synthetic studies on the tetrasubstituted D-ring of cystobactamids lead to potent terephthalic acid antibiotics.

Novel scaffolds for broad-spectrum antibiotics are rare and in strong demand because of the increase in antimicrobial resistance. The cystobactamids, discovered from myxobacterial sources, have a unique hexapeptidic scaffold with five arylamides and possess potent, resistance-breaking properties. This study investigates the role of the central D-ring pharmacophore in cystobactamids, a para-aminobenzoic acid (PABA) moiety that is additionally substituted by hydroxy and isopropoxy functions.

Harnessing Gram-negative bacteria for novel anti-Gram-negative antibiotics.

Natural products have proven themselves as a valuable resource for antibiotics. However, in view of increasing antimicrobial resistance, there is an urgent need for new, structurally diverse agents that have the potential to overcome resistance and treat Gram-negative pathogens in particular. Historically, the search for new antibiotics was strongly focussed on the very successful Actinobacteria.

Expression and characterization of pantothenate energy-coupling factor transporters as an anti-infective drug target.

This study investigates the potential of energy-coupling factor (ECF) transporters as promising anti-infective targets to combat antimicrobial resistance (AMR). ECF transporters, a subclass of ATP-binding cassette (ABC) transporters, facilitate the uptake of B-vitamins across bacterial membranes by utilizing ATP as an energy source. Vitamins are essential cofactors for bacterial metabolism and growth, and they can either be synthesized de novo or absorbed from the environment.

BGC Atlas: a web resource for exploring the global chemical diversity encoded in bacterial genomes.

Secondary metabolites are compounds not essential for an organism's development, but provide significant ecological and physiological benefits. These compounds have applications in medicine, biotechnology and agriculture. Their production is encoded in biosynthetic gene clusters (BGCs), groups of genes collectively directing their biosynthesis.

Structure Revision of Halisphingosine A via Total Synthesis and Bioactivity Studies.

Sphingoid bases are important bioactive lipids found in a variety of organisms, serving as the backbone of sphingolipids, which regulate essential physiological processes. Here we describe the total synthesis and structure revision of halisphingosine A, a sphingoid base initially isolated from marine sponges. To address inconsistencies in the NMR interpretation of this natural product, we developed a synthetic route involving a late-stage enantioselective Henry reaction that allows access to multiple stereoisomers of the proposed halisphingosine A core structure.

Ribosomal peptides with polycyclic isoprenoid moieties.

Isoprenoid modifications of proteins and peptides serve fundamental biological functions and are of therapeutic interest. While C (farnesyl) and C (geranylgeranyl) moieties are prevalent among proteins, known ribosomal peptide prenylations involve shorter-chain units not exceeding farnesyl in size. To our knowledge, cyclized terpene moieties have not been reported from either biomolecule class.

Comparative genomics unravels a rich set of biosynthetic gene clusters with distinct evolutionary trajectories across fungal species (Termitomyces) farmed by termites.

The use of compounds produced by hosts or symbionts for defence against antagonists has been identified in many organisms, including in fungus-farming termites (Macrotermitinae). The obligate mutualistic fungus Termitomyces plays a pivotal role in plant biomass decomposition and as the primary food source for these termites. Despite the isolation of various specialized metabolites from different Termitomyces species, our grasp of their natural product repertoire remains incomplete.