Protein Conformational Exchanges Modulated by the Environment of Outer Membrane Vesicles

Area of Science:

• Biophysics
• Structural Biology
• Biochemistry

Background:

• Protein function is intrinsically linked to protein dynamics and conformational states.
• The cellular environment significantly impacts protein dynamics and conformational equilibria, affecting protein activity.
• Mechanisms by which crowded native environments modulate protein conformational equilibria remain largely unexplored.

Purpose of the Study:

• To investigate how outer membrane vesicle (OMV) environments influence the conformational equilibria of proteins.
• To elucidate the role of macromolecular crowding and periplasmic interactions in protein stabilization within OMVs.
• To assess the utility of OMVs as a platform for in situ protein dynamics studies.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy was employed to monitor protein dynamics.
• Experiments were conducted within isolated outer membrane vesicles (OMVs).
• Macromolecular crowding and specific periplasmic component interactions were analyzed.

Main Results:

• OMV environments were shown to modulate conformational exchanges in the Im7 protein at frustrated sites.
• The Im7 protein's conformation was shifted towards its ground state within OMVs.
• Both macromolecular crowding and quinary interactions with periplasmic components were found to stabilize the Im7 ground state.
• Proteins within OMVs exhibited prolonged NMR measurement times, enabling detailed dynamic studies.

Conclusions:

• The OMV environment plays a crucial role in modulating protein conformational equilibria and function.
• Macromolecular crowding and periplasmic interactions within OMVs contribute to protein stabilization.
• OMVs represent a promising system for in situ investigation of protein structure and dynamics using NMR spectroscopy.