Chemical studies on kasugamycin. V. The structure of kasugamycin

Sulfamate-Tethered Aza-Wacker Strategy for a Kasugamine Synthon

We present our preparation of a kasugamine synthon, which proceeds in 14 steps from a literature epoxide. We expect that this kasugamine derivative can be used for the total syntheses of kasugamycin, minosaminomycin, and analogue antibiotics. A key step in the synthesis is our laboratory's sulfamate-tethered aza-Wacker cyclization.

A novel electrochemical hybrid platform for sensitive determination of the aminoglycoside antibiotic Kasugamycin residues in vegetables

Kasugamycin residues (KASU), a pest control antibiotic, was reported as an ecosystem threat owing to its over-application in plant protection to meet the growing global need for agronomic products. Therefore, we report herein the first electrochemical sensor for fast and sensitive analysis of KASU in vegetables based on the synergetic hybridization between conducting polyserine film (poly (SER)), and carbon nanomaterials including functionalized multiwalled carbon nanotubes (fMWCNTs) and reduced graphene oxide (rGO). The sensor was characterized morphologically using Scanning electron (SEM) and atomic force Microscopy (AFM), while cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for electrochemical characterization. Under the optimized conditions using differential pulse voltammetry (DPV), the sensor exhibited an outstanding sensitivity and selectivity, with a good linear response of 3-106 µg/mL and an assessed limit of detection and quantification of 0.40 and 1.33 µg/mL, respectively. Furthermore, the electrochemical sensor was effectively applied to quantify KASU in cucumber, zucchini, and carrots with a recovery range 95.5-100.1%, and RSD lower than 4.1% (n = 3), showing its applicability and efficiency for selective analysis of KASU in foodstuffs.

Multi-Omics Analysis Reveals that the Antimicrobial Kasugamycin Potential Targets Nitrate Reductase in Didymella segeticola to Achieve Control of Tea Leaf Spot

Because of the lack of effective disease management measures, tea leaf spot-caused by the fungal phytopathogen Didymella segeticola (syn. Phoma segeticola)-is an important foliar disease. The important and widely used agricultural antimicrobial kasugamycin (Ksg), produced by the Gram-positive bacterium Streptomyces kasugaensis, effects high levels of control against crop diseases. The results of this study indicated that Ksg could inhibit the growth of D. segeticola hyphae in vitro with a half-maximal effective concentration (EC₅₀) of 141.18 μg ml^-1. Meanwhile, the curative effect in vivo on the pathogen in detached tea leaves also demonstrated that Ksg induced some morphological changes in organelles, septa, and cell walls as observed by optical microscopy and by scanning and transmission electron microscopy. This may indicate that Ksg disturbs biosynthesis of key metabolites, inhibiting hyphal growth. Integrated transcriptomic, proteomic, and bioinformatic analyses revealed that differentially expressed genes or differentially expressed proteins in D. segeticola hyphae in response to Ksg exposure were involved with metabolic processes and biosynthesis of secondary metabolites. Molecular docking studies indicated that Ksg may target nitrate reductase (NR), and microscale thermophoresis assay showed greater affinity with NR, potentially disturbing nitrogen assimilation and subsequent metabolism. The results indicated that Ksg inhibits the pathogen of tea leaf spot, D. segeticola, possibly by binding to NR, disturbing fungal metabolism, and inducing subsequent changes in hyphal growth and development.

Synthesis, characterization, and application of microbe-triggered controlled-release kasugamycin-pectin conjugate

The controlled and targeted release of pesticides with high water solubility has been a challenge for integrated pest management. In this paper, kasugamycin, an antibiotic broadly used in plant disease control, was covalently conjugated to pectin to form a kasugamycin-pectin conjugate by an amide bond. The conjugate was structurally characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, and thermal gravimetric analysis. The results showed that the conjugate was stable over a wide range of pH and temperatures, as well as under UV irradiation. When incubated with Pseudomonas syringae pv. lachrymans, the conjugate could be activated, releasing the kasugamycin, which made it a promising controlled-release formulation of pesticide.

Bactericidal Compounds Controlling Growth of the Plant Pathogen Pseudomonas syringae pv. actinidiae, Which Forms Biofilms Composed of a Novel Exopolysaccharide

Pseudomonas syringae pv. actinidiae is the major cause of bacterial canker and is a severe threat to kiwifruit production worldwide. Many aspects of the disease caused by P. syringae pv. actinidiae, such as the pathogenicity-relevant formation of a biofilm composed of extracellular polymeric substances (EPSs), are still unknown. Here, a highly virulent strain of P. syringae pv. actinidiae, NZ V-13, was studied with respect to biofilm formation and architecture using a flow cell system combined with confocal laser scanning microscopy. The biofilm formed by P. syringae pv. actinidiae NZ V-13 was heterogeneous, consisting of a thin cellular base layer 5 μm thick and microcolonies with irregular structures. The major component of the EPSs produced by P. syringae pv. actinidiae NZ V-13 bacteria was isolated and identified to be an exopolysaccharide. Extensive compositional and structural analysis showed that rhamnose, fucose, and glucose were the major constituents, present at a ratio of 5:1.5:2. Experimental evidence that P. syringae pv. actinidiae NZ V-13 produces two polysaccharides, a branched α-d-rhamnan with side chains of terminal α-d-Fucf and an α-d-1,4-linked glucan, was obtained. The susceptibility of the cells in biofilms to kasugamycin and chlorine dioxide was assessed. About 64 and 73% of P. syringae pv. actinidiae NZ V-13 cells in biofilms were killed when kasugamycin and chlorine dioxide were used at 5 and 10 ppm, respectively. Kasugamycin inhibited the attachment of P. syringae pv. actinidiae NZ V-13 to solid surfaces at concentrations of 80 and 100 ppm. Kasugamycin was bacteriostatic against P. syringae pv. actinidiae NZ V-13 growth in the planktonic mode, with the MIC being 40 to 60 ppm and a bactericidal effect being found at 100 ppm. Here we studied the formation, architecture, and composition of P. syringae pv. actinidiae biofilms as well as used the biofilm as a model to assess the efficacies of bactericidal compounds.

The antibiotic kasugamycin mimics mRNA nucleotides to destabilize tRNA binding and inhibit canonical translation initiation

Kasugamycin (Ksg) specifically inhibits translation initiation of canonical but not of leaderless messenger RNAs. Ksg inhibition is thought to occur by direct competition with initiator transfer RNA. The 3.35-A structure of Ksg bound to the 30S ribosomal subunit presented here provides a structural description of two Ksg-binding sites as well as a basis for understanding Ksg resistance. Notably, neither binding position overlaps with P-site tRNA; instead, Ksg mimics codon nucleotides at the P and E sites by binding within the path of the mRNA. Coupled with biochemical experiments, our results suggest that Ksg indirectly inhibits P-site tRNA binding through perturbation of the mRNA-tRNA codon-anticodon interaction during 30S canonical initiation. In contrast, for 70S-type initiation on leaderless mRNA, the overlap between mRNA and Ksg is reduced and the binding of tRNA is further stabilized by the presence of the 50S subunit, minimizing Ksg efficacy.

In vitro antibacterial activity of kasugamycin

Kasugamycin is an aminoglycosidic antibiotic which was initially reported as being of potential use against Pseudomonas. Our evaluation of this antibiotic does not confirm this expectation. The median minimal inhibitory concentration (MIC) of the Pseudomonas strains tested was 250 mug/ml and the bactericidal level was 500 mug/ml. Kasugamycin was found to be slightly more active in a more basic medium (Mycin Assay broth) in which the median MIC for 11 Pseudomonas strains was 125 mug/ml. Kasugamycin manifests a modest degree of serum binding. Kasugamycin did not have any appreciable effect against a variety of bacteria tested. The only exceptions were several species of gram-negative bacteria, against which more satisfactory antibiotics already exist. Further evaluation of kasugamycin for potential human use as an antipseudomonal agent does not appear warranted.