Natures wonders: bacteria defense uses protein particles (Introduction)

by David Turell , Thursday, April 16, 2020, 22:27 (1680 days ago) @ David Turell

Pseudomonas releases a lethal protein particle which mechanical attacks enemies:

https://phys.org/news/2020-04-bactericidal-nanomachine-reveal-mechanisms-natural.html

"The particle in the study, an R-type pyocin, is a protein complex released by the bacterium Pseudomonas aeruginosa as a way of sabotaging microbes that compete with it for resources. When a pyocin identifies a rival bacterium, it kills the bacterium by punching a hole in the cell's membrane. P. aeruginosa, frequently a cause of hospital-acquired illness, is found in soil, in water and on fresh produce.

***

"Earlier research by the leaders of the new study described the pyocin's overall structure, albeit in less detail. The largest part of a pyocin is a cylindrical trunk comprising an outer sheath that surrounds an inner tube—the part that punctures. At the bottom of the trunk is a baseplate with six protruding tendrils. When the nanomachine encounters a bacterial cell, it lands on the cell and the tendrils bind to specific structures on the cell's surface.

"In the new paper, the scientists described for the first time a six-stranded collar at the top of the pyocin's trunk, which connects the sheath and inner tube and is important for transmitting energy in the process of triggering the pyocin.

"The latest study also provided previously unknown information about the mechanical action that takes place when a pyocin is triggered: When at least three of the six tendrils bind to the surface of a bacterial cell, the pyocin recognizes that the cell is the specific type of bacterium it is meant to attack. At that point, the tendrils anchor the pyocin to the cell and cause the baseplate to splay out. This, in turn, causes the outer sheath to collapse, driving the inner tube down and across the surface of the target cell.

"Beyond the puncture damage itself, the inner tube leaches energy from the bacterial cell, which causes the cell to die—a detail previously revealed by the researchers.

"'This is a mechanical system that's exquisitely tuned to couple specific recognition of a target cell with deployment of its lethal blow," said co-corresponding author Jeff F. Miller, UCLA's Fred Kavli Professor of NanoSystems Sciences and the director of CNSI. "Understanding how the system is constructed and how its activity is controlled could be used for building new kinds of nanomachines.'"

Comment: Nature can always teach us new tricks. This is so complex it had to be designed.