UCLA researchers in collaboration with researchers at Rutgers University have solved longstanding mysteries surrounding DNA transcription, the first step in carrying out instructions contained in our genes. The breakthrough described in an article in the Nov. 17 issue of the journal Science reveals important structural information about the gyrations of DNA during transcription and the effects of those gyrations on the process.
The discoveries, which inform our understanding of the structure and mechanics of RNAP -- an enzyme responsible for making RNA from a DNA or RNA template -- can help set the stage for new opportunities in combating bacterial diseases that kill 13 million people worldwide each year.
The researchers used single-molecule spectroscopy to monitor the transfer of energy between -- and hence the distance separating -- pairs of fluorescent chemical tags attached to key structural elements of RNAP and the DNA double helix during initiation of the transcription process.
The changes in the distances between these tags confirmed that transcription proceeds initially through a "scrunching" mechanism in which, much like a fisherman reeling in a catch, RNAP remains in a fixed position while it pulls the flexible DNA strand of the gene within itself and past the enzyme's reactive center to form the RNA product.
These changes are inconsistent with other theories that had suggested that RNAP moves along the DNA strand as a complete block in a process resembling the movement of an inchworm.
The research team is comprised of Achillefs N. Kapanidis, Emmanuel Margeat, Sam On Ho, Ekaterine Kortkhonjia and Shimon Weiss of the UCLA Department of Chemistry and Biochemistry, the Department of Physiology and the California NanoSystems Institute (CNSI). The team collaborated with Richard H. Ebright, Howard Hughes Medical Institute, Waksman Institute and Department of Chemistry, Rutgers University.
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Contact: Jennifer Marcus
jmarcus@cnsi.ucla.edu
310-267-4839
University of California - Los Angeles
16-Nov-2006