Natures wonders: how bacteria fish for DNA (Introduction)

by David Turell , Sunday, November 17, 2019, 23:14 (1831 days ago) @ David Turell

They have hairs called pili that reach out into the surroundings:

https://www.sciencedaily.com/releases/2019/10/191021114927.htm

"A new study from Indiana University has revealed a previously unknown role a protein plays in helping bacteria reel in DNA in their environment -- like a fisherman pulling up a catch from the ocean.

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"The act of gobbling up and incorporating genetic material from the environment -- known as natural transformation -- is an evolutionary process by which bacteria incorporate specific traits from other microorganisms, including genes that convey antibiotic resistance.

"Although they may look like tiny arms under a microscope, Dalia said, pili are actually more akin to an erector set that is quickly put together and torn down over and over again. Each "piece" in the structure is a protein sub-unit called the major pilin that assembles into a filament called the pilus fiber.

"'There are two main motors that had previously been implicated in this polymerization and depolymerization process," added Jennifer Chlebek, a Ph.D. student in Dalia's lab, who led the study. "In this study, we show that there is a third motor involved in the depolymerization process, and we start to unravel how it works."

"The two previously characterized "motors" that control the pili's activity are the proteins PilB, which constructs the pili, and PilT, which deconstructs it. These motors run by utilizing ATP, a source of cellular energy. In this study, IU researchers showed that stopping this process, which switches off the power to PilT, does not prevent the retraction of the pili, as previously thought.

"Instead, they found that a third motor protein, called PilU, can power pilus retraction even if PilT is inactive, although this retraction occurs about five times more slowly. The researchers also found that switching off power to both retraction proteins slows the retraction process to a painstaking rate of 50 times slower. An unaltered pilus retracts at a rate of one-fifth of a micron per second.

"Moreover, the study found that switching off PilU affects the strength of pilus retraction, which was measured by collaborators at Brooklyn College. The study also showed that PilU and PilT do not form a "hybrid" motor, but instead that these two independent motors somehow coordinate with one another to mediate pilus retraction."

Comment: This ability to pick up new protective information has helped bacteria be at the start of life and still be here to be as useful as they are in functional biomes. I assume they were designed with this ability to improve their survival. This is too complex a mechanism with its different motors to have been developed by chance mutation.