Characterization of the Biosynthetic Gene Cluster for the Antibiotic Armeniaspirols in Streptomyces armeniacus

Abstract

Armeniaspirols (1–3) are potent antibiotics against Gram-positive pathogens. Through a biosynthetic investigation, we identified four enzymes involved in the structural modification of 1–3. Manipulation of their activity led to the generation of 4–6 and nine novel analogues, 7–15. Bioactivity assessments revealed that the pyrrole chloro group and the methyl group are important for the antimicrobial activities of armeniaspirols, which lays the foundation for future structure optimization and mechanism of action studies of armeniaspirols.

Armeniaspirol A: a novel anti‐Helicobacter pylori agent

“…Based on previous studies, armeniaspirols demonstrated no antimicrobial activity against many Gram‐negative bacteria (Couturier et al ., 2012 ; Qiao et al ., 2019 ). Thus, besides the cell membrane disrupting mode, we speculate there may also have alternative mechanisms for the bactericidal activity of armeniaspirole against H. pylori .…”

“…Armeniaspirols, with a unique chlorinated spiro[4.4]non‐8‐ene scaffold (Table 1 ), are a new class of natural antibacterial products isolated from Streptomyces armeniacus (Couturier et al ., 2012 ). In our recent work, we identified four enzymes involved in the biosynthesis of armeniaspirol A‐C (1 − 3) isolated from S. armeniacus DSM 43125 and manipulated their activity to generate nine new analogues, 7–15 (Table 1 ) (Qiao et al ., 2019 ). Particularly, armeniaspirols 1–6 displayed potent activity against a range of multidrug‐resistant Gram‐positive bacterial pathogens, including Staphylococcus aureus , Enterococcus faecium and Bacillus subtilis (Couturier et al ., 2012 ; Dufour et al ., 2012 ; Qiao et al ., 2019 ).…”

“…In our recent work, we identified four enzymes involved in the biosynthesis of armeniaspirol A‐C (1 − 3) isolated from S. armeniacus DSM 43125 and manipulated their activity to generate nine new analogues, 7–15 (Table 1 ) (Qiao et al ., 2019 ). Particularly, armeniaspirols 1–6 displayed potent activity against a range of multidrug‐resistant Gram‐positive bacterial pathogens, including Staphylococcus aureus , Enterococcus faecium and Bacillus subtilis (Couturier et al ., 2012 ; Dufour et al ., 2012 ; Qiao et al ., 2019 ). However, no inhibitory activity against Gram‐negative bacteria, including Acinetobacter baumannii , Pseudomonas aeruginosa , Klebsiella pneumonia , Salmonella typhimurium , Shigella dysenteriae and Escherichia coli , was observed for all armeniaspirols 1–15 (Qiao et al ., 2019 ).…”

Resistance-guided mining of bacterial genotoxins defines a family of DNA glycosylases

“…Asukamycin contains a modified PKS scaffold and an electrophilic epoxide ring and has been shown to act as both a farsenyltransferase inhibitor and a molecular glue between the UBR7 E3 ubiquitin ligase and the TP53 tumor suppressor, leading to cell death (Hara et al, 1993;Isobe et al, 2020). Armeniaspirol contains a unique chlorinated pyrrole and inhibits the AAA+ proteases ClpXP and ClpYQ leading to cell division arrest in Gram positive bacteria (Labana et al, 2021;Qiao et al, 2019). The other two BGCs produce compounds of known structure but unknown function-tambromycin and JBIR-34/35 are similar NRPS compounds containing densely substituted chlorinated indole and methyloxazoline moieties (Muliandi et al, 2014).…”

Total synthesis and mechanism of action of the antibiotic armeniaspirol A

“…Intriguingly, while we drafted this manuscript, Labana et al published the interaction of the 3 armeniaspirol derivative 4 with the proteases ClpXP and ClpYQ -a mechanism that is different to the ones we report below (see discussion). 9 In a first synthesis of armeniaspirols, 10 we have constructed the spiro- [4.4]non-8-ene scaffold through an attack of the phenolic group at C-8 of the benzoylated pyrrole ring, mimicking the presumed and later confirmed biosynthesis of the natural product 11,12 (Supplementary Scheme S1). The synthesis was short (7 steps, 13.8% overall yield), but the oxidative chlorination conditions led to chloroarmeniaspirol 4 rather than the natural product itself, as the chlorination at the pyrrole ring was inevitably associated with an undesired chlorination at the electron-rich C2 position.…”