Navigation Links
Researchers study virus with unusual properties
Date:12/8/2008

A team of researchers from Penn State University and the University of Chicago has uncovered clues that may explain how and why a particular virus, called N4, injects an unusual substance -- an RNA polymerase protein -- into an E. coli bacterial cell. The results, which are published in the current issue of the journal Molecular Cell, contribute to improved understanding of the infection strategies used by viruses that attack bacterial cells. Such viruses are known as bacteriophages, or phages. The results also may help other researchers to come up with new ideas about ways to kill E. coli bacteria, which can be dangerous to humans.

"Most phages inject only their own DNA into bacterial cells," said Katsu Murakami, a Penn State assistant professor in the Department of Biochemistry and Molecular Biology and a leader of the study. "These phages then use the host bacterial cell's RNA polymerase to synthesize messenger RNA through a process called transcription, which ultimately results in the creation of new phage proteins. These new proteins are used to construct new phages inside the bacterial cell. But the phage that we are studying is different. It injects both its own DNA and its own RNA polymerase into bacterial cells, so it can begin the process of transcription without any help from the bacterial host's RNA polymerase."

The team says that the N4 phage that they are studying is the only phage that they know of that injects its own RNA polymerases into bacterial cells. "We are particularly interested in finding out why N4 injects its own RNA polymerase into bacterial cells and how the N4 RNA polymerase finds the N4 DNA and initiates transcription -- and, ultimately, the creation of new N4 phages -- once it is inside a bacterial cell," said Murakami.

To begin to answer these questions, team member Michael Gleghorn, a former graduate student in the Penn State Department of Biochemistry and Molecular Biology who is now a postdoctoral researcher at the University of Rochester, used X-ray crystallography to obtain a high-resolution three-dimensional image of the N4 phage's RNA-polymerase and DNA molecule. "By modifying the crystallography conditions, Michael obtained an extremely high-resolution picture of the N4 RNA polymerase and DNA molecule. So we are able to analyze protein-DNA interactions much more clearly," said Murakami.

The picture of this RNA polymerase and DNA molecule has enabled the team to investigate how the RNA polymerase initiates transcription of phage DNA from inside a bacterial cell. "When a phage injects its DNA into a bacterial cell, the amount of its DNA is miniscule compared to the amount of host DNA," said Murakami. "We wanted to find out what prevents the N4 RNA polymerase from binding to the bacterial host's DNA rather than to the phage's DNA."

It turns out that the N4 RNA polymerase is able to respond only to DNA that is shaped like a hairpin. Part of the N4 phage's DNA is shaped like a hairpin, whereas the E. coli bacterium's DNA is not shaped like a hairpin. Once the N4 RNA polymerase interacts with the phage's hairpin DNA, it begins to change its shape from a fisted form to a cupped form. By opening up, the RNA polymerase exposes its active site, which allows it to begin the transcription process.

While the researchers determined that the N4 RNA polymerase must change its form in order to bind to the phage DNA, they also found that this transformation isn't the polymerase's first as it progresses through the steps of phage infection. The team found that the polymerase must change form in order to squeeze through the phage's tiny injection tube as it is injected into the E. coli cell. "The diameter of the tube is narrower than the diameter of RNA polymerase," said Murakami. "This means that the enzyme must be unfolded into a longer and thinner structure in order to fit through the tube, and then it is refolded after it is injected into the cell."

The ability of the N4 RNA polymerase to withstand this unfolding and refolding is unique. Therefore, the team decided to experiment with this property by exposing the polymerase to high temperatures. As expected, the high temperatures caused the molecule to unfold. The scientists then cooled the molecule and watched as it reformed into its original shape and regained its functions.

In addition to helping scientists to advance their understanding of the process by which phages infect bacterial cells, Murakami hopes that the novel infection strategy of the N4 phage will be useful in the development of new therapeutic methods for killing E. coli. "The N4 virus injects its own RNA polymerase, which is a type of protein, into the E. coli cell. This system could be replicated and used to deliver proteins or drugs that kill the bacterium," said Murakami. This research was supported by the National Institutes of Health.


'/>"/>

Contact: Barbara K. Kennedy
science@psu.edu
814-863-4682
Penn State
Source:Eurekalert  

Related biology news :

1. Key to curing obesity may lie in worms that destroy their own fat: McGill researchers
2. UC Davis researchers exploring gene therapy to fight AIDS
3. Researchers solve piece of large-scale gene silencing mystery
4. A little wine boosts omega-3 in the body: Researchers find a novel mechanism for a healthier heart
5. Researchers examine role of soil patterns in dam restoration
6. USC researchers head global effort to study genetic risks that contribute to psychiatric diseases
7. PNNL researchers earn top honors at Supercomputing conference
8. Einstein researchers develop technique to count messages made by single genes
9. House Ear Institute, TGen and Belgian researchers identify gene in age-related hearing loss
10. Researchers learn that some good cholesterol isnt good enough
11. URI researchers help score knockout punch on birch tree pest
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Researchers study virus with unusual properties
(Date:4/19/2016)... , UAE, April 20, 2016 ... be implemented as a compact web-based "all-in-one" system solution ... the biometric fingerprint reader or the door interface with ... of modern access control systems. The minimal dimensions of ... ID readers into the building installations offer considerable freedom ...
(Date:4/14/2016)... , April 14, 2016 ... and Malware Detection, today announced the appointment of ... the new role. Goldwerger,s leadership appointment comes ... the heels of the deployment of its platform at ... behavioral biometric technology, which discerns unique cognitive and physiological ...
(Date:3/31/2016)... -- Genomics firm Nabsys has completed a financial  restructuring under ... M.D., who returned to the company in October 2015. ... including Chief Technology Officer, John Oliver , Ph.D., ... Vice President of Software and Informatics, Michael Kaiser ... Bready served as CEO of Nabsys from 2005-2014 and ...
Breaking Biology News(10 mins):
(Date:6/24/2016)... 24, 2016  Regular discussions on a range of subjects ... the two entities said Poloz. Speaking at a ... , he pointed to the country,s inflation target, which ... "In certain areas ... have common economic goals, why not sit down and address ...
(Date:6/23/2016)... , ... June 23, 2016 , ... ... release of its second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” Partnering ... retention in this eBook by providing practical tips, tools, and strategies for clinical ...
(Date:6/23/2016)... Md. , June 23, 2016 A person ... from the crime scene to track the criminal down. ... the U.S. Food and Drug Administration (FDA) uses DNA evidence ... Sound far-fetched? It,s not. The FDA ... sequencing to support investigations of foodborne illnesses. Put as simply ...
(Date:6/23/2016)... NEW YORK , June, 23, 2016  The ... students to envision new ways to harness living systems ... of Modern Art (MoMA) in New York ... more than 130 participating students, showcased projects at MoMA,s ... included Paola Antonelli , MoMA,s senior curator of ...
Breaking Biology Technology: