Structure and dynamics of RNA polymerase II elongation complex.

ABSTRACT

RNA polymerase (Pol) II is a fundamental and important enzyme in the transcription process. However, two mysterious questions have remained unsolved how an unwound bubble of DNA is established and maintained, and how the enzyme moves along the DNA. To answer these questions, we constructed a model structure of the Pol II elongation complex with the 50 base pairs of DNA-24 bases of RNA including the unwound bubble of DNA and performed a molecular dynamics simulation. We obtained a reliable model structure of the Pol II elongation complex in the pre-translocation state which has not yet been determined by the X-ray crystallographic study. The model structure revealed that multiple protein loops work concertedly to form and maintain the bubble structure. We also found that the conformational change of a loop in the Pol II, fork loop 1, couples with the unidirectional movement of the Pol II along the DNA.