Featured Research

from universities, journals, and other organizations

Scientists Glimpse Cellular Machines At Work Inside Living Cells

Date:
November 22, 2002
Source:
NIH/National Cancer Institute
Summary:
Using advanced imaging technology and computational simulations, scientists have, for the first time, glimpsed the action of a cellular machine at work within living cells. The work puts forth a new concept of cellular machines as dynamic protein complexes that are continually building and rebuilding themselves within the cell, rather than the stable structures scientists have traditionally thought them to be.

Using advanced imaging technology and computational simulations, scientists have, for the first time, glimpsed the action of a cellular machine at work within living cells. The work puts forth a new concept of cellular machines as dynamic protein complexes that are continually building and rebuilding themselves within the cell, rather than the stable structures scientists have traditionally thought them to be. The study was published in the Nov. 22, 2002, issue of Science.

Related Articles


Researchers from the National Cancer Institute (NCI), in collaboration with scientists from three other institutions, investigated a cellular machine known as RNA polymerase I, an enzyme that decodes a specific group of genes in the cell. The polymerase is composed of more than ten protein subunits. By analyzing the time it took the many subunits to arrive at a gene and assemble themselves into a functioning protein complex, researchers discovered that RNA polymerase I is constantly assembling and disassembling itself from a large pool of subunits within the cell.

"These findings challenge the current model of cellular machines," said Tom Misteli, Ph.D., of NCI's Cell Biology of Gene Expression Group, the lead investigator on the study. "No longer can we think of cellular machines as stable, static, and precisely-assembled complexes, akin to man-made machines."

Instead, researchers found that polymerase subunits came together and formed a complex each time a gene was read, on average every 1.4 seconds. Computer simulations suggest that each formation resulted from random, chaotic interactions between protein subunits that eventually came together in the proper configuration. Once a complete polymerase finished reading a gene, the subunits quickly disassembled and scattered throughout the cell. Researchers speculate that the dynamic nature of cellular machines allows components to assemble as needed in response to changing environmental conditions.

"The new method we used here allows us to study a whole new dimension in cellular processes - time," said Miroslav Dundr, Ph.D., also of NCI's Cell Biology of Gene Expression Group. Researchers anticipate this approach will lead to unprecedented insight into many other biological processes in the future.

To visualize the polymerase at work within living cells, researchers marked many of the smaller subunits with a small jellyfish protein that emits fluorescent light that can be detected under a microscope. To track the assembly and disassembly of these subunits, the researchers applied a very short, intense laser pulse to the cell. While most of the tagged subunits throughout the cell continued to emit fluorescent light, the laser bleached the fluorescence out of a defined area within the cell. As tagged polymerase subunits began to move into the bleached area, their movement could then be tracked as an increase in fluorescence.

Using the data they had collected about the time it took the fluorescently tagged polymerase subunits to form a complete RNA polymerase I complex and then redisperse, researchers applied computer simulations to test various models of how the polymerase assembles and reads genes. Combining observations made in living cells with computational methods enabled researchers to measure fundamental biophysical properties in living cells. The approach is considered a first step toward complete computer models of living cells and organisms.

Reference:

Dundr M, Hoffman-Rohrer U, Hu Q, Grummt I, Rothblum LI, Phair RD, Misteli T. A kinetic framework for a mammalian RNA polymerase in vivo. Science 2002; 298:1623-1626.


Story Source:

The above story is based on materials provided by NIH/National Cancer Institute. Note: Materials may be edited for content and length.


Cite This Page:

NIH/National Cancer Institute. "Scientists Glimpse Cellular Machines At Work Inside Living Cells." ScienceDaily. ScienceDaily, 22 November 2002. <www.sciencedaily.com/releases/2002/11/021122074846.htm>.
NIH/National Cancer Institute. (2002, November 22). Scientists Glimpse Cellular Machines At Work Inside Living Cells. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2002/11/021122074846.htm
NIH/National Cancer Institute. "Scientists Glimpse Cellular Machines At Work Inside Living Cells." ScienceDaily. www.sciencedaily.com/releases/2002/11/021122074846.htm (accessed October 25, 2014).

Share This



More Matter & Energy News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
Real-Life Transformer Robot Walks, Then Folds Into a Car

Real-Life Transformer Robot Walks, Then Folds Into a Car

Buzz60 (Oct. 24, 2014) Brave Robotics and Asratec teamed with original Transformers toy company Tomy to create a functional 5-foot-tall humanoid robot that can march and fold itself into a 3-foot-long sports car. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Police Testing New Gunfire Tracking Technology

Police Testing New Gunfire Tracking Technology

AP (Oct. 24, 2014) A California-based startup has designed new law enforcement technology that aims to automatically alert dispatch when an officer's gun is unholstered and fired. Two law enforcement agencies are currently testing the technology. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins