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PDBsum entry 4q4z
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Transcription/DNA
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PDB id
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4q4z
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Contents |
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231 a.a.
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1112 a.a.
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1494 a.a.
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94 a.a.
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346 a.a.
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References listed in PDB file
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Key reference
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Title
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Structural basis of transcription initiation by bacterial RNA polymerase holoenzyme.
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Authors
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R.S.Basu,
B.A.Warner,
V.Molodtsov,
D.Pupov,
D.Esyunina,
C.Fernández-Tornero,
A.Kulbachinskiy,
K.S.Murakami.
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Ref.
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J Biol Chem, 2014,
289,
24549-24559.
[DOI no: ]
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PubMed id
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Abstract
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The bacterial RNA polymerase (RNAP) holoenzyme containing σ factor initiates
transcription at specific promoter sites by de novo RNA priming, the first step
of RNA synthesis where RNAP accepts two initiating ribonucleoside triphosphates
(iNTPs) and performs the first phosphodiester bond formation. We present the
structure of de novo transcription initiation complex that reveals unique
contacts of the iNTPs bound at the transcription start site with the template
DNA and also with RNAP and demonstrate the importance of these contacts for
transcription initiation. To get further insight into the mechanism of RNA
priming, we determined the structure of initially transcribing complex of RNAP
holoenzyme with 6-mer RNA, obtained by in crystallo transcription approach. The
structure highlights RNAP-RNA contacts that stabilize the short RNA transcript
in the active site and demonstrates that the RNA 5'-end displaces σ region 3.2
from its position near the active site, which likely plays a key role in σ
ejection during the initiation-to-elongation transition. Given the structural
conservation of the RNAP active site, the mechanism of de novo RNA priming
appears to be conserved in all cellular RNAPs.
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