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

More articles from Life Sciences:

nachricht Study shines light on brain cells that coordinate movement
26.06.2017 | University of Washington Health Sciences/UW Medicine

nachricht New insight into a central biological dogma on ion transport
26.06.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>