Composition and functions of bacterial membrane vesicles.

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Extracellular vesicles, including bacterial outer membrane vesicles (MVs), are produced across all life domains, indicating a fundamental biological process.
• In Gram-negative bacteria, MVs originate from outer membrane blebbing or endolysin-triggered cell lysis, often induced by genotoxic stress.
• Vesiculation mechanisms in Gram-positive and Gram-neutral bacteria are less understood but involve similar lysis and blebbing pathways.

Purpose of the Study:

• To review the diverse types of bacterial outer membrane vesicles (MVs) and their biogenesis mechanisms.
• To elucidate the cargo packaging strategies and functional implications of different MV types.
• To summarize the multifaceted roles of MVs in bacterial physiology, inter-bacterial communication, and host-pathogen interactions.

Main Methods:

• Comprehensive literature review of studies on bacterial outer membrane vesicle (MV) biogenesis, composition, and function.
• Analysis of evidence detailing distinct MV types arising from different production routes (lysis vs. blebbing).
• Synthesis of current knowledge on MV cargo, secretion mechanisms, and biological activities.

Main Results:

• Different biogenesis routes (outer membrane blebbing, endolysin-triggered lysis) generate distinct bacterial outer membrane vesicles (MVs) with varied structures and compositions.
• MVs serve diverse functions, including waste disposal, nutrient acquisition, DNA transfer, phage/antibiotic neutralization, and virulence factor delivery.
• MV-mediated secretion offers advantages over classical secretion systems, with the concept of 'quantal secretion' introduced.

Conclusions:

• Bacterial outer membrane vesicles (MVs) are crucial mediators of bacterial survival, adaptation, and interaction with the environment and host.
• Understanding MV diversity and function is key to harnessing their potential in biotechnology and developing novel therapeutic strategies.
• MV-mediated secretion represents a significant mode of bacterial communication and virulence.