Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genetically identical bacteria can behave in radically different ways

03.01.2014
Uneven distribution of certain mechanisms during cell division creates diversity that can enhance a bacterial population's survival

Although a population of bacteria may be genetically identical, individual bacteria within that population can act in radically different ways.


As these bacterial cells divide, chemotaxis machinery (bright blue and red) localize in one daughter cell.

Credit: Samuel Miller lab/University of Washington

This phenomenon is crucial in the bacteria's struggle for survival. The more diversity a population of bacteria has, the more likely it will contain individuals able to take advantage of a new opportunity or overcome a new threat, including the threat posed by an antibiotic.

In a recent study, researchers at the University of Washington showed that when a bacterial cell divides into two daughter cells there can be an uneven distribution of cellular organelles. The resulting cells can behave differently from each other, depending on which parts they received in the split.

"This is another way that cells within a population can diversify. Here we've shown it in a bacterium, but it probably is true for all cells, including human cells," said Dr. Samuel Miller, UW professor of microbiology, genome sciences, and medicine and the paper's senior author.

Bridget Kulasekara, who obtained a Ph.D in the UW Molecular and Cellular Biology Program, was the paper's lead author. Other contributors included: Hemantha Kulasekara, Matthias Christen, and Cassie Kamischke, who work in Miller's lab, and Paul Wiggins, UW assistant professor of physics and bioengineering. The paper appears in the online journal eLife.

In an earlier paper, Miller and his colleagues showed that when bacteria divided, the concentration of an important regulatory molecule, called cyclic diguanosine monophosphate (c-di-GMP). was unevenly distributed between the two progeny. c-di-GMP is a second messenger molecule. That finding was published in the journal Science in 2010.

Second messenger molecules transmit signals from sensors or receptors on the cell's external membrane to targets within the cell, where they can rapidly alter a wide variety of cellular functions, such as metabolism and mobility.

The ability to respond to external stimuli quickly is important for the bacteria's survival. For instance, to stay alive, a bacterium must not hesitate to swim towards nutrients or away from toxins. This directional movement of microorganisms, spurred by the presence of a helpful or harmful substance, is known as chemotaxis.

"The effect of second messengers is almost immediate," said Miller. "They allow bacteria to change their behavior within seconds."

To detect the difference in c-di-GMP levels between cells, the researchers used a technique called Förster resonance energy transfer microscopy, or FRET microscopy. This allowed them to measure nanomolar changes of the concentration of c-di-GMP within individual bacteria as the changes happened second by second.

Different concentrations of c-di-GMP can have a profound influence on a cell's behavior. For example, in the bacteria Pseudomonas aeruginosa, cells with high levels of c-di-GMP tend to remain still, adhere to surfaces and form colonies. Those with low levels, on the other hand, tend to actively swim about by using a corkscrew-shaped propeller located at one end of the bacterium.

In the latest study, the Miller and his colleagues worked out the molecular mechanism behind the difference in c-di-GMP concentrations seen between daughter cells.

When Pseudomonas cells divide, they pinch in half to create two daughter cells. Although the cells are genetically identical, only one daughter cell can inherit the bacterium's single propeller. The other cell can synthesize its own propeller, but immediately after division the two cells are quite different.

What Miller and his coworkers report in the eLife paper is that the daughter cell that inherits the propeller also inherits an enzyme that is closely associated with the propeller that degrades c-di-GMP, as well as the organelle involved in directing movement toward or away from stimuli that activates this enzyme.

Together these two organelles work in concert to lower the concentration of c-di-GMP and control swimming.

"What we have shown is that the uneven inheritance of organelles is another way cells have to create diversity and increase the chances of the survival of its species," Miller said.

He added that his team's findings may help explain how bacteria resist antibiotic treatments by always having some cells in their populations be in a slow-growing, resting state. Since antibiotics target fast-growing cells, these resting cells are more likely to survive the treatment. The findings might also help explain how some bacteria are able to adhere to and colonize surfaces such as urinary catheters, intravenous lines and heart valves.

In ongoing research, Miller's team is trying to get a better understanding of the signals that can change second messenger concentrations very quickly and is screening compounds that could interfere with or alter those signals. Such compounds could be used to combat drug resistance, for instance, or inhibit a bacterium's ability to adhere to surfaces and form slime-like colonies, called biofilms, that are highly resistant to antibiotics.

The new paper, as well as the earlier study, which appeared in the journal Science in 2010, are both available free online.

Kulasekara et al. c-di-GMP heterogeneity is generated by the chemotaxis machinery to regulate flagellar motility. ELife. 2013;2:e01402. Chisten M et al. Asymmetrical Distribution of the Second Messenger c-di-GMP upon Bacterial Cell Division. Science. 2010; 328(5983):1295-1297 DOI: 10.1126/science.1188658

The research was funded by the National Institute of Allergy and Infectious Diseases (Grant number: 5U54AI057141-09) the National Science Foundation Graduate Research Fellowship (Grant number 2007047910) and the National Institutes of Health (Grant number 1R21NS067579-0).

Leila Gray | EurekAlert!
Further information:
http://www.uw.edu

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>