Navigation Links
Experiment turns up the heat on natural selection, reveals new details of an evolutionary mechanism
Date:6/17/2010

Scientists in Munich report evidence that high concentrations of the molecular "chaperone" proteins GroEL and GroES -- intracellular machines that can stabilize folding proteins under stress -- play a critical role in increasing the maximum temperature at which E. coli bacteria can grow. Massively and permanently elevated levels of the GroE proteins were found in bacteria adapted, step-wise over a period of years, for growth at 48.5 degrees C. This genomic change persisted for more than 600 generations, and molecular analyses ruled out other mechanisms that might account for the increase in heat resistance. The researchers' findings, published in the June 18 edition of the Journal of Biological Chemistry, have important implications for both fundamental evolutionary studies and biotechnology applications.

In addition to being a well established resident of the human digestive tract, Escherichia coli is at home in the lab. It is a model organism as important to biological research as brewer's yeast, the fruit fly, and the mouse. Having evolved for life at our body temperature of around 37 degrees C., wild-type E. coli can be cultivated in the laboratory at temperatures up to but not beyond 44 to 46 degrees C. Pushing the upper temperature at which E. coli could grow to 48.5 degrees C. does not approach the level of heat resistance found in thermophile species, but what this experiment required was a distinct and significant redefinition of "extreme" for E. coli.

To achieve that, Dr. Jeannette Winter and colleagues at the Technische Universitaet Muenchen (TUM) founded three lines of E. coli bacteria from a common ancestor and propagated them under heat stress for hundreds of generations. The step-wise process they designed created conditions under which a combination of normal genomic instability and natural selection would be likely to produce adaptations for growth at extreme temperatures. It took around two years to reach 48.5 degrees C, but after that, adaptation to this new extreme was inherited. The researchers propagated a control population, also descended from the common ancestor, at 37 degrees C.

Exhaustive analysis of cell physiology, protein expression, and genome sequences revealed a number of significant changes. Compared with the control group, the adapted lines of E. coli showed a clearly enhanced capability for living under conditions of heat stress. This was accompanied by reduced growth rates, showing that survival came at a cost in terms of overall fitness, a typical indicator of genomic mutations. One of the most striking changes measured was a 16-fold increase in GroE levels, more than five times what a normal heat shock response in E. coli would be expected to produce. Further analyses of heat shock genes and proteins ruled out other mechanisms -- beyond the role of GroE alone -- as being critical for evolution for life at 48.5 degrees C.

GroE chaperones are known to play an active role in assisting the folding process of other proteins, especially in cases where mutations that could cause improper folding threaten the survival of the cell. This experiment shows that they likely play a uniquely important role -- by mitigating the potentially damaging effects of accumulating mutations on protein folding -- in the evolution of heat resistance in E. coli.

"The correlation between genetic changes and chaperones has been shown not only in bacteria, but also in eukaryotes such as yeast, fruit flies, and fungi," says Dr. Jeannette Winter, a researcher in the TUM Department of Chemistry and a member of the Center for Integrated Protein Science Munich. Beyond yielding insights into evolutionary history, Winter says, further research on these highly conserved mechanisms could shed light on how organisms evolve in response to climate-related stresses in the future. "Better understanding of chaperones might also open the way to targeted generation of organisms for specific purposes -- enhancing their ability, for example, to live under stressful conditions, to break down harmful pollutants, or to produce specific, biotechnologically relevant proteins."

This research was supported by the Emmy-Noether program of the German Research Foundation (DFG), the Elitenetzwerk Bayern, the Fonds der chemischen Industrie, and SFB 594.


'/>"/>

Contact: Patrick Regan
regan@zv.tum.de
49-892-891-0515
Technische Universitaet Muenchen
Source:Eurekalert

Related biology news :

1. Experimental treatment protects monkeys from lethal Ebola virus post-exposure
2. The great pond experiment: Regional vs. local biodiversity
3. Selected highlights of the research being presented at the Experimental Biology 2010 meeting
4. Experimental vaccine protects monkeys against chikungunya
5. ModiFace Launches iLab: An iPhone and iPad App Experimentation Laboratory
6. Experimental drug shows promise against brain, prostate cancers
7. French scientist wins the Journal of Experimental Biology Outstanding Paper Prize 2009
8. Experimental treatments restore partial vision to blind people
9. Free AAPS Webinar will discuss design of experiments
10. New stem cell research could reduce number of animal experiments
11. Experimental treatment halts hypoxic-ischemic brain injury in newborns
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/6/2017)... 5, 2017  Delta ID Inc., a leader in ... for automotive at CES® 2017. Delta ID has collaborated ... demonstrate the use of iris scanning as a secure, ... driver in a car, and as a way to ... Delta ID and Gentex will demonstrate (booth ...
(Date:1/3/2017)... , Jan. 3, 2017 Onitor, provider of ... of Onitor Track, an innovative biometric data-driven program designed ... this month at the 2017 Consumer Electronics Show (CES) ... In the U.S., the World Health Organization (WHO), ... two-thirds of adults who are overweight or obese. WHO ...
(Date:12/20/2016)... -- The rising popularity of mobility services such ... significant interest in keyless access systems. Following the ... (BLE), biometrics and near-field communication (NFC) are poised ... technologies in the automotive industry. This evolution from ... opens the market to specialist companies such as ...
Breaking Biology News(10 mins):
(Date:1/11/2017)... ... 2017 , ... As a graduate student, Scarlet Shell spent ... cause malaria and tuberculosis. Seeing firsthand the ravages those diseases visit on vulnerable ... assistant professor of biology and biotechnology at Worcester Polytechnic Institute (WPI), Shell has ...
(Date:1/11/2017)... Linda, Ca (PRWEB) , ... January 11, 2017 ... ... the U.S. each year and costing healthcare systems more than $23.7 billion, ... while controlling costs. , Among the most common sepsis-causing pathogens are bacteria ...
(Date:1/11/2017)... ... January 11, 2017 , ... IsoPlexis Corporation ... analysis platform to measure the proteomic function of individual cells in patients, today ... (SBIR) grant from the National Institute on Aging of the National Institutes of ...
(Date:1/11/2017)... Rockwall Texas (PRWEB) , ... January 11, 2017 , ... ... Clinics. No Drugs, No Shots and No Surgery for positive back pain relief for ... 150,000 documented positive results worldwide and could be life changing for millions suffering from ...
Breaking Biology Technology: