Leemor Joshua-Tor uses structural and biochemical approaches to elucidate the molecular mechanisms of complex cellular processes. Focusing largely on pathways that control gene expression, her work has defined critical components, particularly the key enzymes and steps involved with RNAi mediated gene silencing. Her work has also uncovered how classical gene expression pathways function, including the Gal4/Gal80 eukaryotic transcriptional switch. In addition, Dr. Joshua-Tor has made contributions to our understanding of DNA replication. She determined how a molecular motor helps unwind two strands of a DNA double helix, offering insight into how other enzymes manipulate nucleic acid.