Crystal structure of a bacterial RNA polymerase holoenzyme at 2.6 A resolution.
In bacteria, the binding of a single protein, the initiation factor sigma, to a multi-subunit RNA polymerase core enzyme results in the formation of a holoenzyme, the active form of RNA polymerase essential for transcription initiation. Here we report the crystal structure of a bacterial RNA polymerase holoenzyme from Thermus thermophilus at 2.6 A resolution. In the structure, two amino-terminal domains of the sigma subunit form a V-shaped structure near the opening of the upstream DNA-binding channel of the active site cleft. The carboxy-terminal domain of sigma is near the outlet of the RNA-exit channel, about 57 A from the N-terminal domains. The extended linker domain forms a hairpin protruding into the active site cleft, then stretching through the RNA-exit channel to connect the N- and C-terminal domains. The holoenzyme structure provides insight into the structural organization of transcription intermediate complexes and into the mechanism of transcription initiation.
Vassylyev
Dmitry G
DG
Cellular Signaling Laboratory, RIKEN Harima Institute at Spring-8, 1-1-1 Kouto, Mikazuki-cho, Sayo, Hyogo 679-5148, Japan. dmitry@yumiyoshi.harima.riken.go.jp
Sekine
Shun-ichi
S
Laptenko
Oleg
O
Lee
Jookyung
J
Vassylyeva
Marina N
MN
Borukhov
Sergei
S
Yokoyama
Shigeyuki
S
D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000378:metabolism; D020035:Holoenzymes / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012808:Sigma Factor / Q000737:chemistry / Q000378:metabolism; D016963:Thermus thermophilus / Q000201:enzymology*; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D020035:Holoenzymes; D012808:Sigma Factor; D004247:DNA; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases; D008274:Magnesium