Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacteria Make Thrift a Habit

30.08.2010
In these lean times, smart consumers refuse to pay a lot for throwaway items, but will shell out a little more for products that can be used again and again. The same is true of bacteria and other microbes, researchers at the University of Michigan have learned.

These organisms "spend" more on proteins that will be used and recycled internally than on proteins that are secreted from the cell and lost to the environment, said graduate student Daniel Smith, lead author of a paper published online in the open access journal mBio.

Proteins are made up of building blocks called amino acids, which vary in size, complexity and chemical characteristics. These differences make some amino acids cheaper for cells to produce than others. Proteins made of mostly cheap amino acids are therefore less costly to the organism than are proteins composed of more energetically expensive amino acids. This much is obvious, but the connection between a protein's location and its expense has not been appreciated until now.

Smith became interested in protein economics while studying a bacterial protein called CsgA, a major component of curli (fibers that decorate the surfaces of E. coli and certain other bacteria and are thought to be involved in causing illness). CsgA is rich in glycine, a cheaply produced amino acid, so CsgA also should be inexpensive for bacteria to produce. But exactly how cheap?

To find out, Smith and co-author Matthew Chapman, an associate professor of molecular, cellular and developmental biology, first looked up previously tallied synthetic costs of all amino acids found in proteins. They used those figures to calculate the total cost of each E. coli protein; then for each protein, they divided total cost by the number of amino acid subunits in the protein to arrive at an average cost.

"When we compared all the proteins in E. coli, we found that CsgA was an outlier," Smith said. "It was one of the cheapest to produce."

That finding makes sense from the bacterium's point of view.

"If you're making lots of curli fibers outside your cell, that's going to be a huge economic cost," Smith said. "If you can reduce that cost, then you can out-compete your neighbors---you're better adapted."

Although most of E. coli's proteins are internal, the results showed that the majority of its cheap proteins are found on the outside. Again, this makes biological sense, Smith said.

"Bacteria are secretion machines," he said. "They're very good at getting proteins out of the cell. But they have no import system. They're very bad at getting proteins back in. So when they secrete proteins, they lose resources."

Smith and Chapman checked their results by using several different measures---chemical energy, mass, carbon content---to calculate protein cost. The conclusion was always the same: extracellular proteins are more economical. In fact, a protein's location is a better predictor of its economy than its abundance, function or size.

The bugs' thrifty ways add up to big savings. Looking just at the proteins found in the flagellum---a tail-like, rotating external structure that some bacteria use to propel themselves through liquids---Smith and Chapman calculated that the energy saved is enough to rotate the flagellum for 24 minutes.

"Considering the expected doubling time of an E. coli cell, that is like getting free fuel for life," Smith said.

E. coli, it turns out, is not the only microbial miser. The researchers performed similar protein economy calculations for a wide range of bacteria, as well as for yeast, and found the same trend: proteins secreted to the extracellular environment are made up of cheaper-to-produce parts than are proteins found inside the cell.

Of course, it isn't individual bacteria and yeast that are deciding what to spend on the proteins they produce. Their tightwad tendencies have been shaped by natural selection.

"Evolution has to balance function and cost," Chapman said. "Function is most important---if an organism makes a cheap protein that doesn't function efficiently, that's a waste. But if an amino acid substitution reduces metabolic cost without affecting function, that will improve the organism's evolutionary fitness."

The research was funded by the National Institutes of Health.

Daniel Smith: www.mcdb.lsa.umich.edu/labs/chapman/profile.php?name=dnlsmith

Matthew Chapman: www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1159

mBio: http://mbio.asm.org/

EDITORS: A photo is available at www.ns.umich.edu/Releases/2010/Aug10/econ_image.html

| Newswise Science News
Further information:
http://www.umich.edu/~newsinfo

Further reports about: CsgA E. coli amino acid bacteria cellular protein microbial miser proteins

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 >>>