Iron Delivery through Membrane Vesicles in Corynebacterium glutamicum

Area of Science:

• Microbiology
• Bacterial Physiology
• Extracellular Vesicles

Background:

• Bacterial membrane vesicles (MVs) are increasingly recognized for diverse biological functions.
• Corynebacterium glutamicum, a model for mycolic acid-containing bacteria, lacks known extracellular iron acquisition systems.
• Understanding iron uptake in C. glutamicum is crucial for its industrial applications and ecological role.

Purpose of the Study:

• To investigate the role of MVs in iron acquisition for Corynebacterium glutamicum.
• To determine the mechanism of iron loading and transfer via C. glutamicum MVs.
• To explore the cross-feeding potential of iron-loaded MVs to other bacterial species.

Main Methods:

• Isolation and characterization of MVs from C. glutamicum.
• Lipid/protein analysis and iron quantification assays.
• Growth promotion assays in iron-limited media.
• Cross-feeding experiments with phylogenetically diverse bacteria.

Main Results:

• C. glutamicum MVs are loaded with ferric iron (Fe3+) through outer mycomembrane blebbing.
• Iron-loaded MVs enhance the growth of C. glutamicum in iron-deficient conditions.
• C. glutamicum MVs are internalized by various bacterial species, including Mycobacterium smegmatis and Rhodococcus erythropolis, facilitating iron uptake.
• Iron loading on MVs is independent of membrane-associated proteins and siderophores in C. glutamicum.

Conclusions:

• C. glutamicum MVs serve as extracellular iron carriers, crucial for bacterial growth.
• MV-mediated iron acquisition in C. glutamicum operates via a novel mechanism distinct from other mycobacteria.
• C. glutamicum MVs have ecological implications, potentially influencing iron availability for other microbes.