Retroviruses can cause tumors and leukemia in animals and humans. The AIDS virus also is a retrovirus. Working with doctoral student Gwen Taylor of Monaca, Pa., Sanders discovered the importance of an amino acid sequence that is part of a protein that was previously thought to be unassuming. Their study shows that this segment of the protein is essential for membrane fusion, and that changing just one amino acid in the sequence could eliminate fusion between the virus and its host. The findings, published in the September issue of Molecular Biology of the Cell, may lead to novel treatments to block the entry of retroviruses and other membrane-possessing viruses, Sanders says.
Sanders studies the structure of proteins that stud the membrane surrounding a retrovirus.
These proteins, called envelope proteins, allow the virus to bind to a host cell and promote the fusion of the virus and cell membranes. It is through this fusion process that the virus enters the cell. Though the process of cell fusion has long been recognized, the structure of these membrane-spanning proteins include regions that were poorly understood, Sanders says. Using the Moloney murine leukemia virus as a model, Sanders and Taylor showed that by replacing part of the sequence they could eliminate membrane fusion, while having no effect on any other known function of the protein. This is the first time that anyone has made a mutation in this region and seen this kind of effect.