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Author Spotlight: Advancing Mycobacterial Biofilm Protocols for Enhanced Bacterial Metabolism Research
Published on: July 12, 2024
C-4-Modified Isotetrones Prevent Biofilm Growth and Persister Cell Resuscitation in Mycobacterium smegmatis
Kingshuk Bag1, Aditya Kumar Pal2, Subhadip Basu3
1Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India.
Abstract:
Hyperphosphorylated nucleotide (p)ppGpp, synthesized by Rel protein, regulates the stringent response pathway responsible for biofilm and persister cell growth in mycobacteria. The discovery of vitamin C as an inhibitor of Rel protein activities raises the prospect of tetrone lactones to prevent such pathways. The closely related isotetrone lactone derivatives are identified herein as inhibitors of the above processes in a mycobacterium. Synthesis and biochemical evaluations show that an isotetrone possessing phenyl substituent at C-4 inhibit the biofilm formation at 400 μg mL-1, 84 h post-exposure, followed by moderate inhibition by the isotetrone possessing the p-hydroxyphenyl substituent. The latter isotetrone inhibits the growth of persister cells at 400 μg mL-1 f.c. when monitored for 2 weeks, under PBS starvation. Isotetrones also potentiate the inhibition of antibiotic-tolerant regrowth of cells by ciprofloxacin (0.75 μg mL-1) and thus act as bioenhancers. Molecular dynamics studies show that isotetrone derivatives bind to the RelMsm protein more efficiently than vitamin C at a binding site possessing serine, threonine, lysine, and arginine.
Insights
Isotetrone lactones inhibit mycobacterial biofilm and persister cell growth by targeting the Rel protein. These compounds also enhance antibiotic effectiveness, offering a new strategy against persistent infections.
Area of Science:
- Microbiology
- Medicinal Chemistry
- Biochemistry
Background:
- The stringent response pathway, regulated by the Rel protein and (p)ppGpp, is crucial for mycobacterial biofilm and persister cell development.
- Vitamin C has been identified as an inhibitor of Rel protein, suggesting potential therapeutic avenues.
- Tetronic acid derivatives, specifically isotetrones, are explored for their ability to modulate these pathways.
Purpose of the Study:
- To identify and synthesize isotetrone lactone derivatives as potential inhibitors of mycobacterial biofilm and persister cell formation.
- To evaluate the efficacy of these derivatives in inhibiting Rel protein-mediated pathways.
- To investigate the potential of isotetrones as bioenhancers in combination with antibiotics.
Main Methods:
- Synthesis of isotetrone lactone derivatives with varying substituents.
- Biochemical assays to assess inhibition of biofilm formation and persister cell growth.
- Molecular dynamics simulations to study binding interactions with the Rel protein (RelMsm).
Main Results:
- An isotetrone derivative with a phenyl substituent at C-4 effectively inhibited biofilm formation.
- An isotetrone with a p-hydroxyphenyl substituent showed moderate inhibition of biofilm formation and inhibited persister cell growth.
- Isotetrones demonstrated bioenhancement effects when combined with ciprofloxacin, potentiating antibiotic activity against tolerant cells.
- Molecular dynamics revealed stronger binding of isotetrones to RelMsm compared to vitamin C.
Conclusions:
- Isotetrone lactones are effective inhibitors of key pathways in mycobacteria, including biofilm formation and persister cell growth.
- These compounds show promise as novel therapeutic agents and bioenhancers for treating mycobacterial infections.
- The detailed binding interactions provide a basis for further drug design and optimization.
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