Navigation Links
Structure of DNA-modifying enzyme In Small Pox Determined

Researchers have determined the structure of DNA-modifying enzyme that could help fight the smallpox disease better. In a study published in the August 4 issue of Molecular Cell//, the researchers at the University of Pennsylvania School of Medicine have presented their findings on the structure of topoisomerase enzyme and how it binds to DNA. The findings could help in developing antiviral agents more effective in fighting the disease.

"This enzyme is one of the most closely studied DNA-modifying enzymes in biology," says Frederic D. Bushman, PhD, Professor of Microbiology, one of the senior authors. "The structure of the DNA complex has been long-awaited." DNA-modifying enzymes bind to specific sequences in the genetic code to aid in the many steps of DNA replication.

The smallpox virus is one of the most easily transmissible infectious diseases known to humans, resulting in up to 30 percent mortality. The efficiency, with which it spreads, combined with the deadly nature of the disease, has raised fears that smallpox could be revived for use in bioterrorism. Knowing the exact three-dimensional structure of smallpox virus proteins could help researchers design antiviral agents, but few structures of whole viral proteins exist.

Poxviruses are large viruses that contain two strands of DNA and replicate themselves entirely in the cytoplasm of infected cells. Poxviruses do not take over the genetic machinery inside the nucleus of the host cell, as many viruses do. Because of this strategy, poxviruses encode many of the enzymes they need to replicate their own genes, and hence reproduce. One of these enzymes is a topoisomerase, which is used by the virus to relieve the excessive twisting of DNA strands that normally occurs during DNA replication and transcription of the viral genes. Upon initial infection, the poxviruses come already equipped with some proteins, including topoisomerases, to kick-start replication.

The stru cture was determined in a collaborative effort between the Bushman lab and the lab of the other senior author Gregory D. Van Duyne, PhD, Professor of Biochemistry and Biophysics and an Investigator with the Howard Hughes Medical Institute (HHMI). Using purified topoisomerase enzyme that had been expressed in bacterial cells, they bound the enzyme to short segments of DNA that contained the viral topoisomerase's specific recognition sequence. They then determined the three-dimensional structure of the topoisomerase-DNA complex using X-ray crystallography.

One of the primary differences between the viral topoisomerase enzyme and the closely related human enzyme that functions in the nucleus of all human cells is that the viral enzyme only relaxes supercoiled DNA when it binds to specific DNA sequences. The structure of the poxvirus topoisomerase-DNA complex provides some important clues about how this recognition and activation mechanism works.

"The more the viral enzyme differs from the human nuclear enzyme, the more likely it is that inhibitors could be developed that are specific to the viral enzymes," says Bushman.

Knowing the three-dimensional structure of the smallpox virus topoisomerase-DNA complex will also facilitate the design of agents to combat poxvirus infections. Topoisomerases are some of the most widely targeted proteins by drugs that are intended to inhibit growth of the cell. Drugs that target topoisomerases generally stabilize an intermediate of the enzyme's reaction in which one of the DNA strands is broken. If these breaks are not repaired, the DNA cannot be replicated and the cell dies.

In the case of smallpox virus, the hope is that drugs targeted to the viral topoisomerase enzyme will prevent viral replication through a similar mechanism. The X-ray structure provides a template for designing small molecules that could stabilize the broken DNA in the intermediate form, thereby killing smallpox virus p articles.

Source: Eurkalert

Related medicine news :

1. Relationship Between Genetic Structure And Quality of Life
2. Abnormal Brain Structure One Of The Reasons For Depression in Adolescents
3. Structure of the brain to increase risk for anxiety disorders
4. Changes In Brain Structure From Methamphetamine Abuse And HIV Infection
5. Almond Structure in the Brain Intrigues Researchers
6. Controversy over Fees Structure in Private Medical Colleges
7. Controversy Over The Fee Structure In Private Medical Colleges Surfaces Yet Again
8. Education Structure In Indian Schools To Be Revamped Soon
9. Neither Management Nor Students Happy With New Fee Structure
10. DNA-bound p53 Tumor Suppressor Protein Structure Determined
11. Penn Researchers Throw Light on the Structure Of Smallpox Virus Protein
Post Your Comments:

(Date:6/27/2016)... ... June 27, 2016 , ... ... professionals, announced today its affiliation with Tennessee Counseling Association. This new ... network of the Tennessee Counseling Association, adding exclusive benefits and promotional offers. , ...
(Date:6/27/2016)... ... June 27, 2016 , ... recently awarded their ... Eyeglasses . , Millions of individuals in the United States and Canada wear eyeglasses. ... way to both correct vision and make a fashion statement. Even celebrities use glasses ...
(Date:6/26/2016)... ... June 26, 2016 , ... Pixel Film Studios Released ProSlice ... "Film editors can give their videos a whole new perspective by using the ... of Pixel Film Studios. , ProSlice Levels contains over 30 Different presets to ...
(Date:6/26/2016)... ... June 26, 2016 , ... ... have been diagnosed with endometriosis. These women need a treatment plan to not ... comprehensive approach that can help for preservation of fertility and ultimately achieving a ...
(Date:6/25/2016)... ... June 25, 2016 , ... The temporary closing of Bruton Memorial Library on June ... , brings up a new, often overlooked aspect of head lice: the parasite’s ability to ... is not a common occurrence, but a necessary one in the event that lice have ...
Breaking Medicine News(10 mins):
(Date:6/26/2016)...  VMS Rehab Systems, Inc. ( ) reported ... required to build a strong and stable market for ... on the OTC Markets-pink current trading platform. ... are seeing an anomaly in market trading activities that ... the Company, but shareholders and market players as well. ...
(Date:6/24/2016)... 2016   Bay Area Lyme Foundation , ... Center for Tick Borne Illness , Harvard Medical ... Hacking Medicine, University of California, Berkeley, and the ... five finalists of Lyme Innovation , the ... 100 scientists, clinicians, researchers, entrepreneurs, and investors from ...
(Date:6/24/2016)... and SAN CLEMENTE, Calif. , June ... -based mobile pulmonary function testing company, is now able to ... devices developed by ndd Medical Technologies , Inc. ... done in hospital-based labs.  Thanks to ndd,s EasyOne PRO ® , ... , can get any needed testing done in the comfort of ...
Breaking Medicine Technology: