Navigation Links
Clearing jams in copy machinery

Bacteria and humans use a number of tools to direct perhaps the most important function in cells -- the accurate copying of DNA during cell division. New research published this week in Molecular Cell from the laboratory of Rockefeller University's Michael O'Donnell, a Howard Hughes Medical Institute Investigator, now shows that one of these proteins, the beta sliding clamp, serves as a toolbelt from which the correct proteins are retrieved to enable DNA replication in the face of DNA damage.

The replication machinery inside the cell's nucleus is made up of a collection of enzymes including DNA polymerases, sliding clamps and clamp loaders. Bacteria have five known DNA polymerases (higher organisms such as humans have more). As the ring-shaped beta sliding clamp works its way along the DNA double helix, a network of proteins work together to unwind the two strands. Polymerases then add, in assembly line fashion, nucleotide bases -- the building blocks that make up DNA -- to convert the now-single-stranded templates into two new duplex DNA molecules.

The new research shows that two different DNA polymerases, the high fidelity Pol III replicase and the low fidelity Pol IV, coordinate their action to cross obstacles encountered in the replication process. They attach themselves at the same time to one beta sliding clamp. Pol III copies the original DNA, and acts as a proofreader to catch any misspellings and cuts any base that is wrong. But Pol III is a perfectionist, and can stall if it encounters a problem. Pol IV, on the other hand, lays down bases without checking for errors, keeping the process moving even when Pol III gets stuck. The findings by O'Donnell and his colleagues show that, because both polymerases are bound simultaneously to the beta clamp, it can pull either of the polymerases out if its toolbelt as needed.

O'Donnell and his colleagues propose two explanations for how the polymerase switch is controlled.

"One possibili ty is that the beta clamp may sense when Pol III stalls, triggering a change in beta that pulls the polymerase from the primed site, allowing Pol IV to take over synthesis," O'Donnell says. Or, Pol III, upon stalling, may loosen its grip on the template and allow Pol IV to bind the primed site instead.


'"/>

Source:Rockefeller University


Related biology news :

1. Carnegie Mellon scientists develop tool that uses MRI to visualize gene expression in living animals
2. Robot-based system developed at Carnegie Mellon detects life in Chiles Atacama desert
3. Green catalyst destroys pesticides and munitions toxins, finds Carnegie Mellon University
4. Carnegie Mellon University research reveals how cells process large genes
5. Team led by Carnegie Mellon University scientist finds first evidence of a living memory trace
6. Carnegie Mellon scientists create PNA molecule with potential to build nanodevices
7. Carnegie Mellon U. transforms DNA microarrays with standard Internet communications tool
8. Carnegie Mellon develops non-invasive technique to detect transplant rejection at cellular level
9. Carnegie Mellon scientists show brain uses optimal code for sound
10. DNA conclusive yet still controversial, Carnegie Mellon professor says
11. Teens unaware of sexually transmitted diseases until they catch one, Carnegie Mellon study finds
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:5/20/2016)... , May 20, 2016  VoiceIt is ... partnership with VoicePass. By working together, ... experience.  Because VoiceIt and VoicePass take slightly different ... engines increases both security and usability. ... excitement about this new partnership. "This ...
(Date:5/9/2016)... Elevay is currently known as ... for high net worth professionals seeking travel for work ... world, there is still no substitute for a face-to-face ... your deal with a firm handshake. This is why ... of citizenship via investment programs like those offered by ...
(Date:4/28/2016)... Sweden , April 28, 2016 First ... M (139.9), up 966% compared with the first quarter of 2015 ... profit totaled SEK 589.1 M (loss: 18.8) and the operating margin ... 7.12 (loss: 0.32) Cash flow from operations was SEK ... The 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. ...
Breaking Biology News(10 mins):
(Date:6/24/2016)... ... June 24, 2016 , ... Researchers at the Universita Politecnica delle ... people with peritoneal or pleural mesothelioma. Their findings are the subject of a new ... , Diagnostic biomarkers are signposts in the blood, lung fluid or tissue of mesothelioma ...
(Date:6/23/2016)... ... 2016 , ... UAS LifeSciences, one of the leading manufacturers ... Probiotics, into Target stores nationwide. The company, which has been manufacturing high quality ... list of well-respected retailers. This list includes such fine stores as Whole Foods, ...
(Date:6/23/2016)... /PRNewswire/ - FACIT has announced the creation of ... company, Propellon Therapeutics Inc. ("Propellon" or "the Company"), ... portfolio of first-in-class WDR5 inhibitors for the treatment ... represent an exciting class of therapies, possessing the ... cancer patients. Substantial advances have been achieved with ...
(Date:6/23/2016)... HOUSTON , June 23, 2016 ... agreement with the Cy-Fair Sports Association to serve ... of the agreement, Houston Methodist Willowbrook will provide ... education and connectivity with association coaches, volunteers, athletes ... partner with the Cy-Fair Sports Association and to ...
Breaking Biology Technology: