Structural basis of transcription: role of the trigger loop in substrate specificity and catalysis.
New structures of RNA polymerase II (pol II) transcribing complexes reveal a likely key to transcription. The trigger loop swings beneath a correct nucleoside triphosphate (NTP) in the nucleotide addition site, closing off the active center and forming an extensive network of interactions with the NTP base, sugar, phosphates, and additional pol II residues. A histidine side chain in the trigger loop, precisely positioned by these interactions, may literally "trigger" phosphodiester bond formation. Recognition and catalysis are thus coupled, ensuring the fidelity of transcription.
Wang
Dong
D
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Bushnell
David A
DA
Westover
Kenneth D
KD
Kaplan
Craig D
CD
Kornberg
Roger D
RD
D000546:Amanitins / Q000737:chemistry; D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009711:Nucleotides / Q000378:metabolism; D011487:Protein Conformation; D012319:RNA Polymerase II / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013379:Substrate Specificity; D014158:Transcription, Genetic
D000546:Amanitins; D009711:Nucleotides; D006639:Histidine; D004247:DNA; D012319:RNA Polymerase II; D008274:Magnesium