As a result, bacteria have evolved many mechanisms to deal with stress, including systems designed to pump toxic molecules out of the cell. One of these mechanisms is the formation, packaging, and release of outer membrane vesicles. All bacteria produce vesicles. In Gram-negative bacteria, which have an inner membrane and an outer membrane separated by a thin layer of peptidoglycan, vesicles bud off of the outer membrane. To help deal with stress, bacteria package these vesicles with misfolded proteins and other compounds that are toxic to the bacterial cell.
While research has uncovered many roles for vesicles in the context of mammalian host-pathogen interactions, very little is known about the role of bacterial vesicles in the environment. One way to study interaction with the environment is in the context of plant host-pathogen interactions.
My work aims to uncover:
1) how bacterial vesicles from plant pathogens interact with the plant innate immune system
2) what types of molecules are packaged in plant pathogen vesicles
3) if and how vesicles could be used in an agricultural setting
However, vesicles are also used for more than defense against stress. Mammalian pathogens package vesicles with virulence factors that harm the host and help the bacteria survive. In fact, vesicles are a very successful strategy for packaging hydrophobic toxins and protecting soluble proteins from degradation in the harsh host environment.
Bacteria encounter a wide array of stress in their environment, particularly in the context of host-pathogen interactions. For example, when a human has a bacterial infection their immune system works to eliminate the pathogen through heat stress (fever) and sending immune cells to the site of infection (inflammation). These immune cells can sometimes capture the pathogen leading to even more stress for the bacteria such as oxidative and pH stress.