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

More articles from Life Sciences:

nachricht Nesting aids make agricultural fields attractive for bees
20.07.2017 | Julius-Maximilians-Universität Würzburg

nachricht The Kitchen Sponge – Breeding Ground for Germs
20.07.2017 | Hochschule Furtwangen

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>