Scientists said that that the protein was not required for cell growth or division and hence if they would target Ssu72 interactions with the virus’ protein, they may be able to stop the replication of HIV.
The team had begun by identifying a list of 50 or so proteins that interacted with a well-known protein HIV created called Tat.
The findings had been surprising to the team because Tat, a relatively small protein, was previously thought to have a simpler role. Jones’ lab had previously discovered the CycT1 protein, another critical protein that Tat used to begin the steps of replicating the virus and all these years, scientists thought that Tat only had this one partner (CycT1), but when looked at a bit harder, they had found that it also bound and stimulated the Ssu72 phosphatase, which controlled an immediately preceding step to switch on HIV.
CycT1 was needed for normal cell function, so it may not be an ideal anti-viral target. However, the team had found that Ssu72 was not required for making RNA for most host cell genes in the way it was used by HIV, making it a potentially promising target for drug therapy.
Many proteins that Tat interacted with were essential for normal cellular transcription so those couldn’t be targeted unless you want to kill normal cells and Ssu72 seemed to be different–at least in the way it is used by HIV.
Katherine Jones, Salk professor in the Regulatory Biology Laboratory and senior author of the study has said that the virus cannot live without Tat and Tat acted as a lookout in the cell for the virus, telling the virus when the cellular environment was favorable for its replication.
When the environment was right, Tat kicked off the virus’ transcription, the process by which HIV read and replicated its building blocks (RNA) to spread throughout the body.
The study was published in the journal Genes & Development.