Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecule by molecule, new assay shows real-time gene activity

16.03.2006


First ’movie’ of gene expression in live cells shows proteins being made in small bursts



Chemists at Harvard University have developed the first technique providing a real-time, molecule-by-molecule "movie" of protein production in live cells. Their direct observation of fluorescently tagged molecules in single cells -- providing striking real-time footage of the birth of individual new protein molecules inside -- greatly increases scientists’ precision in probing genetic activity.

Using the new assay, described this week in the journal Science, researchers led by Harvard’s X. Sunney Xie counted, one by one, protein molecules generated in small bursts within cells as multiple ribosomes bound to single copies of mRNA complete the process by which DNA, an organism’s long-term genetic repository, yields its crop of proteins. These random, or stochastic, bursts of protein expression are described in detail in a separate paper Xie and colleagues present this week in Nature.


"Although central to life processes, the expression of many important genes takes place at very low levels, making it difficult or impossible to observe using current technologies," says Xie, professor of chemistry and chemical biology in Harvard’s Faculty of Arts and Sciences. "Our experiments provide the most sensitive means to date of observing real-time activity of single molecules inside cells. This new technique could provide us with unprecedented insights into gene expression and many other fundamental biological processes in living cells." The central dogma of molecular biology holds that DNA is transcribed into mRNA, which is then translated into proteins. But several technical hurdles have hampered study of these key processes. Researchers’ current understanding of this two-step pathway is built upon their averaging of genetic and biochemical activity across large populations of cells and molecules, masking the essential randomness of the process at the cellular level. Furthermore, much of our knowledge on the workings of the molecular machinery involved in gene expression comes from experiments done in vitro, rather than in living cells. Finally, the low sensitivity of current techniques for detecting gene expression has restricted analysis to highly expressed genes.

Xie’s new assay addresses all three limitations. He and his colleagues melded a yellow fluorescent protein called Venus with Tsr, a hydrophobic membrane protein. The inclusion of the Tsr domain serves to anchor the fused protein to a cell’s membrane, sidestepping the longstanding difficulty of imaging single proteins zipping about in cell cytoplasm, where diffuse fluorescent signals tend to be overwhelmed by background noise.

The gene coding for this combined protein was substituted for the well-studied lacZ gene in the Escherichia coli chromosome. When lacZ’s regulatory machinery allows the modified gene to be converted into a handful of protein molecules, these Tsr-Venus hybrids migrate to the cell membrane, where each attaches firmly. The clearly visible flash from each Tsr-Venus molecule -- which when viewed across a population of cells looks somewhat akin to a sea of cellular paparazzi -- serves as an indication of that single protein molecule’s production.

"Dr. Xie’s experiments are the first to obtain quantitative, real-time information on protein expression in living cells at the single-molecule level," says Jeremy M. Berg, director of the National Institute of General Medical Sciences, which funded the work in part. "His imaging methods open up new possibilities for addressing fundamental questions about the precise events and factors involved in regulating these essential processes. This is exactly the sort of highly innovative research with broad applicability that the National Institutes of Health Director’s Pioneer Award was created to support."

Steve Bradt | EurekAlert!
Further information:
http://www.harvard.edu

More articles from Life Sciences:

nachricht Carnegie Mellon researchers probe hydrogen bonds using new technique
10.12.2018 | Carnegie Mellon University

nachricht A new molecular player involved in T cell activation
07.12.2018 | Tokyo Institute of Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

Im Focus: Substitute for rare earth metal oxides

New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals

Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.

Im Focus: A bit of a stretch... material that thickens as it's pulled

Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.

Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...

Im Focus: The force of the vacuum

Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.

The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

Expert Panel on the Future of HPC in Engineering

03.12.2018 | Event News

 
Latest News

New method gives microscope a boost in resolution

10.12.2018 | Physics and Astronomy

Carnegie Mellon researchers probe hydrogen bonds using new technique

10.12.2018 | Life Sciences

ETRI exchanged quantum information on daylight in a free-space quantum key distribution

10.12.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>