Electrochemical modification of everninomicin D

Ganguly, Ashit K.; Kabasakalian, Peter; Morton, J. J.; Sarre, Olga Z.; Westcott, Anita; Kalliney, Sami; Mangiaracina, Pietro; Papaphilippou, A.

doi:10.1039/c39800000056

Cited by 7 publications

(5 citation statements)

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“…Truncated conjugate Evn O showed an increased MIC of approximately 10 μg/mL. Evn M was not isolated in sufficient quantities for activity analysis, but its activity has been reported elsewhere and is comparable to Evn N/O and Evn P. 14 Interaction of Evn P with the Bacterial Ribosome. Orthosomycins, such as Evn A and avilamycin (Avn), have been shown to bind to a distinct site on the large ribosomal subunit, 15−17 which is located far (60 Å) from the peptidyltransferase center (PTC) active site and ribosomal tunnel where the majority of large-subunit targeting antibiotics interact, such as the chloramphenicols and macrolides (Figure 3A).…”

Section: ■ Resultsmentioning

confidence: 91%

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Bifunctional Nitrone-Conjugated Secondary Metabolite Targeting the Ribosome

et al. 2020

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Many microorganisms possess the capacity for producing multiple antibiotic secondary metabolites. In a few notable cases, combinations of secondary metabolites produced by the same organism are used in important combination therapies for treatment of drug-resistant bacterial infections. However, examples of conjoined roles of bioactive metabolites produced by the same organism remain uncommon. During our genetic functional analysis of oxidase-encoding genes in the everninomicin producer Micromonospora carbonacea var. aurantiaca, we discovered previously uncharacterized antibiotics everninomicin N and O, comprised of an everninomicin fragment conjugated to the macrolide rosamicin via a rare nitrone moiety. These metabolites were determined to be hydrolysis products of everninomicin P, a nitrone-linked conjugate likely the result of nonenzymatic condensation of the rosamicin aldehyde and the octasaccharide everninomicin F, possessing a hydroxylamino sugar moiety. Rosamicin binds the erythromycin macrolide binding site approximately 60 Å from the orthosomycin binding site of everninomicins. However, while individual ribosomal binding sites for each functional half of everninomicin P are too distant for bidentate binding, ligand displacement studies demonstrated that everninomicin P competes with rosamicin for ribosomal binding. Chemical protection studies and structural analysis of everninomicin P revealed that everninomicin P occupies both the macrolide- and orthosomycin-binding sites on the 70S ribosome. Moreover, resistance mutations within each binding site were overcome by the inhibition of the opposite functional antibiotic moiety binding site. These data together demonstrate a strategy for coupling orthogonal antibiotic pharmacophores, a surprising tolerance for substantial covalent modification of each antibiotic, and a potential beneficial strategy to combat antibiotic resistance.

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Section: ■ Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Bifunctional Nitrone-Conjugated Secondary Metabolite Targeting the Ribosome

et al. 2020

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“…One such compound, evernimicin (SCH 27899) (10,11,12) is currently undergoing evaluation as a therapeutic agent. It has been shown to have potent activity against many gram-positive bacteria, including emerging problem organisms such as vancomycinresistant enterococci, methicillin-resistant staphylococci, and penicillin-resistant pneumococci (16).…”

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confidence: 99%

Mutations in Ribosomal Protein L16 Conferring Reduced Susceptibility to Evernimicin (SCH27899): Implications for Mechanism of Action

Adrian

Zhao²,

Black³

et al. 2000

Antimicrob Agents Chemother

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A clinical isolate of Streptococcus pneumoniae (SP#5) that showed decreased susceptibility to evernimicin (MIC, 1.5 g/ml) was investigated. A 4,255-bp EcoRI fragment cloned from SP#5 was identified by its ability to transform evernimicin-susceptible S. pneumoniae R6 (MIC, 0.03 g/ml) such that the evernimicin MIC was 1.5 g/ml. Nucleotide sequence analysis of this fragment revealed that it contained portions of the S10-spc ribosomal protein operons. The nucleotide sequences of resistant and susceptible isolates were compared, and a point mutation (thymine to guanine) that causes an Ile52-Ser substitution in ribosomal protein L16 was identified. The role of this mutation in decreasing susceptibility to evernimicin was confirmed by direct transformation of the altered L16 gene. The presence of the L16 mutation in the resistant strain suggests that evernimicin is an inhibitor of protein synthesis. This was confirmed by inhibition studies using radiolabeled substrates, which showed that the addition of evernimicin at sub-MIC levels resulted in a rapid decrease in the incorporation of radiolabeled isoleucine in a susceptible isolate (SP#3) but was much less effective against SP#5. The incorporation of isoleucine showed a linear response to the dose level of evernimicin. The incorporation of other classes of labeled substrates was unaffected or much delayed, indicating that these were secondary effects.Everninomicins are a class of oligosaccharide antibiotics isolated from Micromonospora carbonaceae (31). One such compound, evernimicin (SCH 27899) (10, 11, 12) is currently undergoing evaluation as a therapeutic agent. It has been shown to have potent activity against many gram-positive bacteria, including emerging problem organisms such as vancomycinresistant enterococci, methicillin-resistant staphylococci, and penicillin-resistant pneumococci (16). In fact, there were no staphylococcal, enterococcal, and pneumococcal isolates that displayed resistance to evernimicin in either the investigation by Jones and Barrett (16) or a more-recent worldwide survey of clinical isolates, including isolates known to be resistant to other antibiotics (R. S. Hare, F. J. Sabatelli, and the Ziracin Susceptibility Testing Group, Abstr. 38th Intersci. Conf. Antimicrob. Agents Chemother., abstr. E-119, p. 204, 1998). The paucity of isolates showing resistance to evernimicin is presumably a result of no prior clinical exposure to a drug similar to the family of everninomicins. The lack of cross-resistance to evernimicin, however, would suggest that the mechanism of action is novel and that prior selection leading to resistance to other antimicrobials will not impact the efficacy of evernimicin.Previous studies with another oligosaccharide antibiotic, avilamycin (33), showed protein synthesis inhibition as the mechanism of action, apparently by interacting with the 30S ribosomal subunit. Nevertheless, avilamycin lacks the nitrosugar moiety that distinguishes the everninomicin class of antibiotics, and the mechanism of action of everninomicin...

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“…One such compound, evernimicin (SCH27899), has been evaluated as a therapeutic agent (Ziracin) (6). Evernimicin has been shown to have potent activity against many gram-positive bacteria, including vancomycin-resistant enterococci, methicillin-resistant staphylococci, and penicillin-resistant pneumococci (9).…”

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confidence: 99%

Evernimicin (SCH27899) Inhibits a Novel Ribosome Target Site: Analysis of 23S Ribosomal DNA Mutants

Adrian

Mendrick²,

Loebenberg³

et al. 2000

Antimicrob Agents Chemother

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Spontaneous mutants of susceptible clinical and laboratory isolates of Streptococcus pneumoniae exhibiting reduced susceptibility to evernimicin (SCH27899; MIC, 0.5 to 4.0 mg/liter) were selected on plates containing evernimicin. Four isolates that did not harbor mutations in rplP (which encodes ribosomal protein L16) were further analyzed. Whole chromosomal DNA or PCR products of the 23S ribosomal DNA (rDNA) operons from these mutants could be used to transform the susceptible S. pneumoniae strain R6 to resistance at frequencies of 10 ؊5 and 10 ؊4 , respectively, rates 10-to 100-fold lower than that for a single-allele chromosomal marker. The transformants appeared slowly (48 to 72 h) on selective medium, and primary transformants passaged on nonselective medium produced single colonies that displayed heterogeneous susceptibilities to evernimicin. A single passage on selective medium of colonies derived from a single primary transformant homogenized the resistance phenotype. Sequence analysis of the 23S rDNA and rRNA from the resistant mutants revealed single, unique mutations in each isolate at the equivalent Escherichia coli positions 2469 (A 3 C), 2480 (C 3 T), 2535 (G 3 A), and 2536 (G 3 C). The mutations map within two different stems of the peptidyltransferase region of domain V. Because multiple copies of rDNA are present in the chromosome, gene conversion between mutant and wild-type 23S rDNA alleles may be necessary for stable resistance. Additionally, none of the characterized mutants showed cross-resistance to any of a spectrum of protein synthesis inhibitors, suggesting that the target site of evernimicin may be unique.

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Electrochemical modification of everninomicin D

Cited by 7 publications

References 0 publications

Bifunctional Nitrone-Conjugated Secondary Metabolite Targeting the Ribosome

Bifunctional Nitrone-Conjugated Secondary Metabolite Targeting the Ribosome

Mutations in Ribosomal Protein L16 Conferring Reduced Susceptibility to Evernimicin (SCH27899): Implications for Mechanism of Action

Evernimicin (SCH27899) Inhibits a Novel Ribosome Target Site: Analysis of 23S Ribosomal DNA Mutants

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