Genetics Home   Molecular Biology 2nd Edition               Robert F. Weaver
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Chapter 10

  1. Two landmark papers from Roger Kornberg's lab have revealed the structure of yeast RNA polymerase II at high resolution. The first shows four mobile modules within the enzyme, one of which is a clamp that holds the DNA template over the active center. The clamp is open in this structure, which would allow promoter DNA to bind before transcription begins. Two metal ions are at the active center. One is tightly bound, and the other might be exchangeable. (Cramer, P., D.A. Bushnell, and R.D. Kornberg. 2001. Structural basis of transcription: RNA polymerase II at 2.8 ngstrom resolution. Science 292:1863-76)

  2. The second paper from Kornberg's group shows the crystal structure of the enzyme during transcription. Double-stranded DNA enters the channel in the enzyme and unwinds before reaching the active center. Nine base pairs of DNA-RNA hybrid have formed perpendicular to the duplex DNA. The 3'-end of the RNA lies in the nucleotide addition site, which is adjacent to a pore that may allow nucleotides access to the active site. The clamp is now closed over the template DNA and the RNA product. This structure explains many of the known characteristics of transcription. (Gnatt, A.L., P. Cramer, J. Fu, D.A. Bushnell, and R.D. Kornberg 2001. Structural basis of transcription: An RNA polymerase II elongation complex at 3.3 resolution. Science 292:1876-82)

  3. See item #1 under Chapter 15.

  4. See item #2 under Chapter 11.

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