Scientists Solve a 50-Year Mystery – How Do Bacteria Move? - SciTechDaily

University of Virginia scientists person solved a decades-old mystery.

Researchers from the University of Virginia School of Medicine and their colleagues person solved a long-standing enigma concerning however E. coli and different bacteria move.

Bacteria determination guardant by coiling their long, threadlike appendages into corkscrew shapes, which service arsenic makeshift propellers. However, since the “propellers” are formed of a azygous protein, experts are puzzled arsenic to however precisely they bash this.

The lawsuit has been solved by an planetary squad headed by UVA’s Edward H. Egelman, Ph.D., a pioneer successful the high-tech tract of cryo-electron microscopy (cryo-EM). Cryo-EM and almighty machine modeling were utilized by the researchers to uncover what nary accepted airy microscope could see: the antithetic operation of these propellers astatine the level of idiosyncratic atoms.

“While models person existed for 50 years for however these filaments mightiness signifier specified regular coiled shapes, we person present determined the operation of these filaments successful atomic detail,” said Egelman, of UVA’s Department of Biochemistry and Molecular Genetics. “We tin amusement that these models were wrong, and our caller knowing volition assistance pave the mode for technologies that could beryllium based upon specified miniature propellers.”

Blueprints for Bacteria’s ‘Supercoils’

Different bacteria person 1 oregon galore appendages known arsenic a flagellum, or, successful the plural, flagella. A flagellum is made up of thousands of subunits, each of which are identical. You’d ideate that specified a process would beryllium straight, oregon astatine slightest somewhat flexible, but it would forestall the bacteria from moving. This is owed to the information that specified shapes cannot make thrust. A rotating, corkscrew-like propeller is required to determination a bacterium forward. Scientists telephone the improvement of this signifier “supercoiling,” and they present cognize however bacteria bash it aft much than 50 years of research.

Egelman and his colleagues discovered that the macromolecule that makes up the flagellum whitethorn beryllium successful 11 antithetic states utilizing cryo-EM. The corkscrew signifier is formed by the nonstop operation of these states.

It has been known that the propeller successful bacteria is rather antithetic than akin propellers utilized by hearty one-celled organisms called archaea. Archaea are recovered successful immoderate of the astir utmost environments connected Earth, specified arsenic successful astir boiling pools of acid, the precise bottommost of the water and successful petroleum deposits heavy successful the ground.

Egelman and colleagues utilized cryo-EM to analyse the flagella of 1 signifier of archaea, Saccharolobus islandicus, and recovered that the macromolecule forming its flagellum exists successful 10 antithetic states. While the details were rather antithetic than what the researchers saw successful bacteria, the effect was the same, with the filaments forming regular corkscrews. They reason that this is an illustration of “convergent evolution” – erstwhile quality arrives astatine akin solutions via precise antithetic means. This shows that adjacent though bacteria and archaea’s propellers are akin successful signifier and function, the organisms evolved those traits independently.

“As with birds, bats, and bees, which person each independently evolved wings for flying, the improvement of bacteria and archaea has converged connected a akin solution for swimming successful both,” said Egelman, whose anterior imaging enactment saw him inducted into the National Academy of Sciences, 1 of the highest honors a idiosyncratic tin receive. “Since these biologic structures emerged connected Earth billions of years ago, the 50 years that it has taken to recognize them whitethorn not look that long.”

Reference: “Convergent improvement successful the supercoiling of prokaryotic flagellar filaments” by Mark A.B. Kreutzberger, Ravi R. Sonani, Junfeng Liu, Sharanya Chatterjee, Fengbin Wang, Amanda L. Sebastian, Priyanka Biswas, Cheryl Ewing, Weili Zheng, Frédéric Poly, Gad Frankel, B.F. Luisi, Chris R. Calladine, Mart Krupovic, Birgit E. Scharf and Edward H. Egelman, 2 September 2022, Cell.
DOI: 10.1016/j.cell.2022.08.009

The survey was funded by the National Institutes of Health, the U.S. Navy, and Robert R. Wagner.