Linearmycins are lytic membrane-targeting antibiotics.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Linearmycins are polyketides initially identified for antifungal properties.
• Previous research demonstrated linearmycins induce lysis and colony degradation in Bacillus subtilis.
• Extracellular vesicles containing linearmycins were shown to lyse B. subtilis.

Purpose of the Study:

• To elucidate the mechanism by which linearmycins induce bacterial lysis.
• To identify the direct cellular target of linearmycins.
• To investigate the role of extracellular vesicles in linearmycin-mediated bacterial killing.

Main Methods:

• Testing linearmycin efficacy against various Gram-positive bacteria.
• Assessing linearmycin-induced lysis under conditions of inhibited cellular metabolism and growth.
• Measuring cytoplasmic membrane depolarization in B. subtilis upon linearmycin exposure.
• Utilizing liposome models to evaluate linearmycin interaction with lipid bilayers in vitro.

Main Results:

• Linearmycins inhibited growth in all tested Gram-positive bacteria, but lysis was specific to certain Bacillus species.
• Lysis occurred independently of bacterial metabolism, indicating an intrinsic membrane-disrupting capability.
• Linearmycin treatment led to rapid cytoplasmic membrane depolarization and loss of viability in B. subtilis.
• Linearmycins disrupted liposomes, confirming their ability to directly interact with and destabilize lipid bilayers.

Conclusions:

• The cytoplasmic membrane is the direct antibacterial target of linearmycins.
• Linearmycins possess intrinsic membrane-lytic activity, distinct from cell-wall targeting antibiotics.
• Extracellular vesicle-mediated delivery of linearmycins contributes to their antibacterial action against B. subtilis.