Earth Science News  





. RNA World Remnant

Ronald Breaker and the chemical structure of cyclic di-GMP. Credit: Yale
by Staff Writers
Yale CA (SPX) Jul 22, 2008
Some bacterial cells can swim, morph into new forms and even become dangerously virulent - all without initial involvement of DNA. Yale University researchers describe in the journal Science how bacteria accomplish this amazing feat - and in doing so provide a glimpse of what the earliest forms of life on Earth may have looked like.

To initiate many important functions, bacteria sometimes depend entirely upon ancient forms of RNA, once viewed simply as the chemical intermediary between DNA's instruction manual and the creation of proteins, said Ronald Breaker, the Henry Ford II Professor of Molecular, Cellular and Developmental Biology at Yale and senior author of the study.

Proteins carry out almost all of life's cellular functions today, but many scientists like Breaker believe this was not always the case and have found many examples in which RNA plays a surprisingly large role in regulating cellular activity.

The Science study illustrates that - in bacteria, at least - proteins are not always necessary to spur a host of fundamental cellular changes, a process Breaker believes was common on Earth some 4 billion years ago, well before DNA existed.

"How could RNA trigger changes in ancient cells without all the proteins present in modern cells? Well, in this case, no proteins, no problem," said Breaker, who is also a Howard Hughes Medical Institute investigator.

Breaker's lab solved a decades-old mystery by describing how tiny circular RNA molecules called cyclic di-GMP are able to turn genes on and off. This process determines whether the bacterium swims or stays stationary, and whether it remains solitary or joins with other bacteria to form organic masses called biofilms.

For example, in Vibrio cholerae, the bacterium that causes cholera, cyclic di-GMP turns off production of a protein the bacterium needs to attach to human intestines.

The tiny RNA molecule, comprised of only two nucleotides, activates a larger RNA structure called a riboswitch. Breaker's lab discovered riboswitches in bacteria six years ago and has since shown that they can regulate a surprising amount of biological activity.

Riboswitches, located within single strands of messenger RNA that transmit a copy of DNA's genetic instructions, can independently "decide'' which genes in the cell to activate, an ability once thought to rest exclusively with proteins.

Breaker had chemically created riboswitches in his own lab and - given their efficiency at regulating gene expressions - predicted such RNA structures would be found in nature. Since 2002, almost 20 classes of riboswitches, including the one described in today's paper, have been discovered, mostly hidden in non-gene-coding regions on DNA.

"We predicted that there would be an ancient 'RNA city' out there in the jungle, and we went out and found it,'' Breaker said.

Bacterial use of RNA to trigger major changes without the involvement of proteins resolves one of the questions about the origin of life: If proteins are needed to carry out life's functions and DNA is needed to make proteins, how did DNA arise?

The answer is what Breaker and other researchers call the RNA World. They believe that billions of years ago, single strands of nucleotides that comprise RNA were the first forms of life and carried out some of the complicated cellular functions now done by proteins. The riboswitches are highly conserved in bacteria, illustrating their importance and ancient ancestry, Breaker said.

Understanding how these RNA mechanisms work could lead to medical treatments as well, Breaker noted. For instance, a molecule that mimics cyclic di-GMP could be used to disable or disarm bacterial infections such as cholera, he said.

Community
Email This Article
Comment On This Article

Share This Article With Planet Earth
del.icio.usdel.icio.us DiggDigg RedditReddit
YahooMyWebYahooMyWeb GoogleGoogle FacebookFacebook



Related Links
Darwin Today At TerraDaily.com




Tempur-Pedic Mattress Comparison

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News
Natural Selection May Not Produce The Best Organisms
Washington DC (SPX) Jul 22, 2008
"Survival of the fittest" is the catch phrase of evolution by natural selection. While natural selection favors the most fit organisms around, evolutionary biologists have long wondered whether this leads to the best possible organisms in the long run.

.
Get Our Free Newsletters Via Email
  



  • Asia's disaster response in spotlight at security talks
  • Thousands evacuated as storm hits China: state media
  • China quake zone govt to sell luxury HQ after outcry: report
  • China quake sends 1.4 million back into poverty: report

  • Ontario joins US carbon trading clan
  • Australia's Rudd hits out at critics of carbon trading scheme
  • Australia to set up carbon trading scheme by 2010
  • CSIRO Climate Adaptation Flagship Launched

  • NASA Works To Improve Short-Term Weather Forecasts
  • NASA's Deep Impact Films Earth As An Alien World
  • ESA To Consult The Science Community On Earth Explorer Selection
  • GeoEarthScope NorCal LiDAR Topography Data Available

  • LS Power Announces Creation Of Dedicated Renewable Business Unit
  • Oil prices rally on Dolly storm, Iran concerns
  • WindConnect Joins In Flat Ridge Wind Farm Groundbreaking
  • Battelle To Consult With Japan CCS Company on Carbon Sequestration

  • US scientists scrap major AIDS vaccine test
  • The Way To A Virus' Heart Is Through Its Enzymes
  • Discovery Of Key Malaria Proteins Could Mean Sticky End For Parasite
  • Pandemic Mutations In Bird Flu Revealed

  • Lionfish Decimating Tropical Fish Populations And Coral Reefs
  • RNA World Remnant
  • Vocal Communication Evolved With Ancient Species
  • Natural Selection May Not Produce The Best Organisms

  • Mafia rubbish dumps seized as Berlusconi declares Naples clean
  • Peru fears environmental mining disaster
  • 80 percent of Vietnam factories breach pollution rules: study
  • Boeing And Alenia Support Composite Industrial Recycling Plant

  • Research Publications Online: Too Much Of A Good Thing
  • Archaeologists Trace Early Irrigation Farming In Ancient Yemen
  • Do We Think That Machines Can Think
  • Will Our Future Brains Be Smaller

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement