Predator Bacterium Capitalizes on Membrane Protein's Unique Design to Swallow Competitors
In a groundbreaking discovery, researchers at the University of Birmingham have uncovered the unique fivefold structure of PopA, a membrane protein in the predatory bacterium Bdellovibrio bacteriovorus. This finding offers a new folding and membrane insertion pattern that could revolutionise the field of antibacterial research.
The unique fivefold structure of PopA forms a bowl-shaped assembly, unlike classical outer membrane proteins that typically form single barrels or three-barrel clusters. This pentameric assembly, with a hydrophobic inner surface and an outer ring of lysine residues, facilitates PopA's ability to interact with and potentially move between the outer and inner membranes of bacterial cells.
The outer lysine ring may guide its insertion or positioning within the cell wall, enabling it to cross or span the space between membranes. The hydrophobic lining inside the bowl shape suggests a lipid-trapping mechanism that could anchor or move the protein through the membrane environment. This architecture supports Bdellovibrio's ability to recognise, breach, and manipulate bacterial membranes.
The potential applications of this discovery are vast. By enhancing PopA’s lipid-trapping "trap" to boost Bdellovibrio's predator function or dialing it down to reduce toxicity in therapeutic contexts, new antibiotics or antibacterial strategies could be developed.
This research, led by structural biologist Andrew Lovering, challenges the current understanding of outer membrane proteins, which has been dominated by studies on E. coli and Pseudomonas. Finding 'rulebreakers' like PopA in other species gives scientists a deeper understanding of what these biomolecules are capable of.
Further analysis uncovered homologues of PopA across a variety of bacterial species that form tetramers, hexamers, and sometimes even nonamers, all having the same lipid-trapping feature. However, one important question that remains unknown is how PopA goes from the predator to the prey, whether it is secreted through an outer membrane vesicle or by another way.
The new research has sparked intrigue among microbiology experts, such as Mohammed Kaplan at the University of Chicago, who are fascinated by the implications for understanding fundamental biological questions related to evolution and cell-cell interaction.
The findings were made possible through the use of x-ray crystallography and cryo-electron microscopy, methods that have proven instrumental in unveiling the intricate structures of these microscopic predators. The research focuses on PopA, a porin-like protein found in the outer membrane of B. bacteriovorus.
As we continue to unravel the mysteries of PopA and its potential applications, we move one step closer to developing novel antibacterial agents that could combat harmful bacteria more effectively. The potential applications of this research are vast, ranging from medicine to biotechnology, and the implications are far-reaching.
The unique fivefold structure of PopA, discovered in the bacterium Bdellovibrio bacteriovorus, could potentially revolutionize the field of medical-conditions treatment, as it offers a new lipid-trapping mechanism that technology such as cryo-electron microscopy has revealed could anchor or move proteins through the membrane environment.
With further analysis showing homologues of PopA across various bacterial species, each with a similar lipid-trapping feature, the applications of this discovery span beyond antibacterial research, extending into the realms of medicine and technology.
