Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

DNA-reeling bacteria yield new insight on how superbugs acquire drug-resistance

22.10.2019

A new imaging method invented at Indiana University leads to a discovery about how bacteria use thin hair-like surface appendages called pili for 'natural transformation'

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.


Clockwise: A bacterium retracts its pili, reeling in a piece of DNA in the environment. This action facilitates "natural transformation," a process by which bacterium acquire new genetic traits, including antibiotic resistance.

Image courtesy the Dalia Lab, Indiana University

The discovery was made possible by a new imaging method invented at IU that let scientists see for the first time how bacteria use their long and mobile appendages -- called pili -- to bind to, or "harpoon," DNA in the environment. The new study, reported Oct. 18 in the journal PLOS Genetics, focuses on how they reel their catch back in.

By revealing the mechanisms involved in this process, the study's authors said the results may help hasten work on new ways to stop bacterial infection.

"The issue of antibiotic resistance is very relevant to this work since the ability of pili to bind to, and 'reel in,' DNA is one of the major ways that bacteria evolve to thwart existing drugs," said Ankur Dalia, an assistant professor in the IU Bloomington College of Arts and Sciences' Department of Biology, who is senior author on the study. "An improved understanding of this 'reeling' activity can help inform strategies to stop it."

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.

The need for new methods to stop bacterial infection is growing since overuse of existing antibiotics, which speeds how quickly infectious organisms evolve to outsmart these drugs, is causing the world to quickly run out of effective treatments. By 2050, it's estimated that 10 million people could die each year from antimicrobial 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.

"While the PilU protein had previously been implicated in pilus activity, its exact role has been difficult to determine because cells that lack this protein generally only have very subtle effects," Chlebek added. "Our observation that PilU can support pilus retraction in a mutant strain, when we threw a wrench in the PilT motor, was the key to unlocking how this protein aids in the depolymerization of pili."

The ability to precisely measure the pili's retraction rate -- and therefore precisely measure the impact of altering the proteins that affect this process -- was made possible by the ability to see pili under a microscope, which was not possible until the breakthrough imaging method invented at IU.

"The ability to fluorescently dye the pili was huge," Dalia said. "It allowed us to not only see the pili's activity but also measure it in ways which simply would not have been possible in the past."

Next, Chlebek aims to learn more about how the pili still retract when the power is switched off to both retraction motors, as well as explore how these insights could apply to understanding pili activity in other strains of bacteria.

###

This research was supported in part by the National Institutes of Health. Additional IU authors on the study were Brittany Herrin and Hannah Hughes, both Ph.D. students; Triana Dalia, a research associate in the Department of Biology; and Joseph Che-Yen Wang, an assistant scientist at the IU Electron Microscopy Center. The researchers at Brooklyn College were Aleksandra S. Ratkiewicz, Rasman Rayyan and Nicolas Biais.

Media Contact

Kevin D. Fryling
kfryling@iu.edu
812-856-2988

 @IUNewsroom

http://newsinfo.iu.edu 

Kevin D. Fryling | EurekAlert!
Further information:
http://dx.doi.org/10.1371/journal.pgen.1008448

Further reports about: DNA antibiotic resistance bacteria bacterial infection proteins retraction superbugs

More articles from Life Sciences:

nachricht Structure of a mitochondrial ATP synthase
19.11.2019 | Science For Life Laboratory

nachricht Mantis shrimp vs. disco clams: Colorful sea creatures do more than dazzle
19.11.2019 | University of Colorado at Boulder

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Atoms don't like jumping rope

Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.

By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...

Im Focus: Images from NJIT's big bear solar observatory peel away layers of a stellar mystery

An international team of scientists, including three researchers from New Jersey Institute of Technology (NJIT), has shed new light on one of the central mysteries of solar physics: how energy from the Sun is transferred to the star's upper atmosphere, heating it to 1 million degrees Fahrenheit and higher in some regions, temperatures that are vastly hotter than the Sun's surface.

With new images from NJIT's Big Bear Solar Observatory (BBSO), the researchers have revealed in groundbreaking, granular detail what appears to be a likely...

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

Structure of a mitochondrial ATP synthase

19.11.2019 | Life Sciences

The measurements of the expansion of the universe don't add up

19.11.2019 | Physics and Astronomy

Ayahuasca compound changes brainwaves to vivid 'waking-dream' state

19.11.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>