In what may be a first step toward expanding the arsenal against HIV, UC Irvine .
Researchers targeted Nef, a protein responsible for accelerating the development of acquired immunodeficiency syndrome, or AIDS. Nef was targeted with small molecules synthesized by the researchers – molecules that disrupted Nef’s interaction with other proteins.
The technique used for identifying the synthetic molecules also may lead to new drug therapies with improved treatment options.
The researchers used a scientific technique called “phage display,” which is used to identify small molecule inhibitors that can disrupt interactions between proteins. According to Gregory Weiss, lead researcher and assistant professor in the Department of Chemistry at UCI, his research team attached the Nef protein to the surface of a harmless virus, then created synthetic molecules that could target and dislodge the protein.
This is the first time phage display has been used to identify molecules that disrupt protein-protein interactions.
While the method was successful, Weiss said the molecules identified proved toxic to cells. He is now seeking to develop less toxic compounds that will have high potencies against Nef without causing collateral damage. A key benefit of this achievement, he added, would be the development of therapies using smaller molecules, which can often be used in oral medications. Therapies that rely on larger molecules are used in medications injected by needle.
“By proving small molecules can be effective for targeting Nef, we’ve shown how researchers can expand the fight against AIDS,” said Weiss.
The researchers reported their findings last week in the online edition of the Proceedings of the National Academy of Science. The print version of the research paper will appear in the Sept. 28 issue of the journal.
Human immunodeficiency virus, commonly known as HIV, is known to cause AIDS. The virus attacks the body’s immune system, making the body vulnerable to infections and certain cancers. Symptoms of acute HIV infection may include fever, headache, fatigue and enlarged lymph nodes. The virus is spread most commonly by having unprotected sex with an infected person.
Funded by the Arnold and Mabel Beckman Foundation, the Burroughs Wellcome Fund and the National Institutes of Health, the three-year research effort involved innovation in small molecule discovery. Conducted entirely at UCI, the multidisciplinary research involved a partnership among three laboratories and a collaboration of scientists in chemistry, molecular biology, biochemistry and pathology.
Besides Weiss, co-authors of the study are Allison Olszewski, Ken Sato, Zachary D. Aron, Frederick Cohen, Aleishia Harris, Brenda R. McDougall, W. Edward Robinson Jr., and Larry Overman. Olszewski, a doctoral candidate in chemistry, is the lead author of the paper. Overman’s laboratory synthesized the small molecules; Robinson’s laboratory tested them for cellular toxicity and anti-HIV activity; and Weiss’ laboratory performed measurements to identify which molecules were inhibitory to Nef.
Led by chemist Gregory Weiss, the researchers invented a system for identifying guanidine alkaloids – small molecule inhibitors of protein-protein interactions. They attached the Nef protein to the surface of a bacteriophage (a virus whose host is a bacterium), which provided a ‘handle’ that could be tracked by the researchers to determine whether Nef was binding to three cellular proteins, as is Nef’s function. (Although Nef is able to bind well to the three proteins in the absence of the bacteriophage, the researchers used the bacteriophage simply as a handle to watch the binding.)
Next, the researchers looked for a mechanism that would disrupt binding by Nef. They found that their synthesized molecules and Nef both competed to bind with the cellular proteins. Each time the molecules succeeded, Nef was dislodged from binding to the three cellular proteins and thus inhibited.