Structure of an RNA polymerase II-TFIIB complex and the transcription initiation mechanism.
Previous x-ray crystal structures have given insight into the mechanism of transcription and the role of general transcription factors in the initiation of the process. A structure of an RNA polymerase II-general transcription factor TFIIB complex at 4.5 angstrom resolution revealed the amino-terminal region of TFIIB, including a loop termed the "B finger," reaching into the active center of the polymerase where it may interact with both DNA and RNA, but this structure showed little of the carboxyl-terminal region. A new crystal structure of the same complex at 3.8 angstrom resolution obtained under different solution conditions is complementary with the previous one, revealing the carboxyl-terminal region of TFIIB, located above the polymerase active center cleft, but showing none of the B finger. In the new structure, the linker between the amino- and carboxyl-terminal regions can also be seen, snaking down from above the cleft toward the active center. The two structures, taken together with others previously obtained, dispel long-standing mysteries of the transcription initiation process.
Liu
Xin
X
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Bushnell
David A
DA
Wang
Dong
D
Calero
Guillermo
G
Kornberg
Roger D
RD
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry* / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D035581:Transcription Factor TFIIB / Q000737:chemistry* / Q000378:metabolism*; D014158:Transcription, Genetic
C073680:SUA7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035581:Transcription Factor TFIIB; D012319:RNA Polymerase II