Seth A. Darst, Ph.D.

Research

My research explores the mechanism and regulation of transcription by determining the three-dimensional structures of RNA polymerase and other associated proteins. Our laboratory is purifying, crystallizing and determining the structures of proteins involved in transcription, using a combination of approaches including x-ray crystallography and electron microscopy. Members of the lab have purified, crystallized and determined the structure of the core RNA polymerase from the thermophilic eubacteria Thermus aquaticus. The results were the first high-resolution structure of a multisubunit cellular RNA polymerase. We then tracked the path of the transcript RNA and the template DNA through the polymerase structure using RNA-protein and DNA-protein crosslinks, a method that gave the scientists a model of the elongation complex that is made as the polymerase moves along the DNA. We have also worked to understand how the introduction of specific molecules impacts RNA polymerase. To determine how the antibiotic rifampicin inhibits RNA polymerase function, we used a combination of x-ray crystallography and biochemical studies. Recent research in the lab has also described the structure of the protein, revealing a new mechanism by which bacteria prevent premature and precocious activation of their genes. Another recent structural study by members of the lab described the transcription-repair coupling factor, a protein cells use both to stop DNA transcription at sites of DNA damage and to recruit repair proteins to fix the damage.