Structural Basis of Transcription: Nucleotide Selection by Rotation in the RNA Polymerase II Active Center

详细信息    查看全文

• 作者：Kenneth D. Westover ; David A. Bushnell and Roger D. Kornberg
• 刊名：Cell
• 出版年：2004
• 出版时间：12 November 2004
• 年：2004
• 卷：119
• 期：4
• 页码：481-489
• 全文大小：516 K

文摘

Binding of a ribonucleoside triphosphate to an RNA polymerase II transcribing complex, with base pairing to the template DNA, was revealed by X-ray crystallography. Binding of a mismatched nucleoside triphosphate was also detected, but in an adjacent site, inverted with respect to the correctly paired nucleotide. The results are consistent with a two-step mechanism of nucleotide selection, with initial binding to an entry (E) site beneath the active center in an inverted orientation, followed by rotation into the nucleotide addition (A) site for pairing with the template DNA. This mechanism is unrelated to that of single subunit RNA polymerases and so defines a new paradigm for the large, multisubunit enzymes. Additional findings from these studies include a third nucleotide binding site that may define the length of backtracked RNA; DNA double helix unwinding in advance of the polymerase active center; and extension of the diffraction limit of RNA polymerase II crystals to 2.3 Å.