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Open data
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Basic information
Entry | Database: PDB / ID: 8xme | ||||||
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Title | Backtracked Pol IV transcription elongation complex | ||||||
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![]() | TRANSCRIPTION/DNA/RNA / elongation / Pol IV / RNA polymerase / TRANSCRIPTION-DNA-RNA complex | ||||||
Function / homology | ![]() RNA polymerase IV complex / stomatal complex patterning / siRNA-mediated long-distance post-transcriptional gene silencing / transposable element silencing by siRNA-mediated heterochromatin formation / RNA polymerase V complex / gene silencing by siRNA-directed DNA methylation / stomatal complex development / siRNA transcription / DNA/RNA hybrid binding / regulatory ncRNA-mediated post-transcriptional gene silencing ...RNA polymerase IV complex / stomatal complex patterning / siRNA-mediated long-distance post-transcriptional gene silencing / transposable element silencing by siRNA-mediated heterochromatin formation / RNA polymerase V complex / gene silencing by siRNA-directed DNA methylation / stomatal complex development / siRNA transcription / DNA/RNA hybrid binding / regulatory ncRNA-mediated post-transcriptional gene silencing / siRNA processing / regulatory ncRNA-mediated gene silencing / plastid / RNA polymerase complex / defense response to fungus / regulation of immune response / heterochromatin / RNA polymerase II, core complex / : / DNA-directed RNA polymerase activity / DNA-templated transcription initiation / ribonucleoside binding / : / : / : / : / : / : / DNA-directed RNA polymerase / nucleic acid binding / single-stranded RNA binding / protein dimerization activity / RNA-directed RNA polymerase / RNA-directed RNA polymerase activity / nucleotide binding / DNA-templated transcription / nucleolus / mitochondrion / DNA binding / zinc ion binding / nucleoplasm / metal ion binding / nucleus / cytoplasm Similarity search - Function | ||||||
Biological species | ![]() ![]() synthetic construct (others) | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.1 Å | ||||||
![]() | Huang, K. / Fang, C.L. / Zhang, Y. | ||||||
Funding support | ![]()
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![]() | ![]() Title: Transcription elongation of the plant RNA polymerase IV is prone to backtracking. Authors: Chengli Fang / Kun Huang / Xiaoxian Wu / Hongwei Zhang / Zhanxi Gu / Jiawei Wang / Yu Zhang / ![]() Abstract: RNA polymerase IV (Pol IV) forms a complex with RNA-directed RNA polymerase 2 (RDR2) to produce double-stranded RNA (dsRNA) precursors essential for plant gene silencing. In the "backtracking- ...RNA polymerase IV (Pol IV) forms a complex with RNA-directed RNA polymerase 2 (RDR2) to produce double-stranded RNA (dsRNA) precursors essential for plant gene silencing. In the "backtracking-triggered RNA channeling" model, Pol IV backtracks and delivers its transcript's 3' terminus to RDR2, which synthesizes dsRNA. However, the mechanisms underlying Pol IV backtracking and RNA protection from cleavage are unclear. Here, we determined cryo-electron microscopy structures of Pol IV elongation complexes at four states of its nucleotide addition cycle (NAC): posttranslocation, guanosine triphosphate-bound, pretranslocation, and backtracked states. The structures reveal that Pol IV maintains an open DNA cleft and kinked bridge helix in all NAC states, loosely interacts with the nucleoside triphosphate substrate, and barely contacts proximal backtracked nucleotides. Biochemical data indicate that Pol IV is inefficient in forward translocation and RNA cleavage. These findings suggest that Pol IV transcription elongation is prone to backtracking and incapable of RNA hydrolysis, ensuring efficient dsRNA production by Pol IV-RDR2. | ||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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PDBx/mmCIF format | ![]() | 933.1 KB | Display | ![]() |
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PDB format | ![]() | Display | ![]() | |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 38473MC ![]() 8xmbC ![]() 8xmcC ![]() 8xmdC M: map data used to model this data C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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1 |
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Components
-DNA-directed RNA polymerase IV subunit ... , 2 types, 2 molecules AG
#1: Protein | Mass: 168101.781 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() Gene: NRPD1, NRPD1a, RMD3, RPD1, SDE4, SMD2, At1g63020, F16M19.19, F16P17.19 Production host: ![]() ![]() |
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#7: Protein | Mass: 19873.297 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
-DNA-directed RNA polymerases IV and V subunit ... , 2 types, 2 molecules BD
#2: Protein | Mass: 132848.047 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
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#4: Protein | Mass: 22447.604 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
-DNA-directed RNA polymerases II, IV and V subunit ... , 7 types, 7 molecules CFHIJKL
#3: Protein | Mass: 35503.219 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
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#6: Protein | Mass: 16670.346 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
#8: Protein | Mass: 16626.299 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
#9: Protein | Mass: 13297.145 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
#10: Protein | Mass: 8323.690 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
#11: Protein | Mass: 13582.286 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
#12: Protein | Mass: 5905.768 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
-Protein , 2 types, 2 molecules EM
#5: Protein | Mass: 24340.389 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
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#13: Protein | Mass: 129494.531 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
-DNA chain , 2 types, 2 molecules NQ
#14: DNA chain | Mass: 12512.046 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) synthetic construct (others) |
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#16: DNA chain | Mass: 12111.806 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) synthetic construct (others) |
-RNA chain , 1 types, 1 molecules O
#15: RNA chain | Mass: 5852.540 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) synthetic construct (others) |
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-Non-polymers , 2 types, 10 molecules 


#17: Chemical | ChemComp-ZN / #18: Chemical | ChemComp-MG / | |
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-Details
Has ligand of interest | N |
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Has protein modification | N |
-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
Component | Name: Backtracked Pol IV transcription elongation complex / Type: COMPLEX / Entity ID: #1-#16 / Source: RECOMBINANT |
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Molecular weight | Value: 0.65 kDa/nm / Experimental value: NO |
Source (natural) | Organism: ![]() ![]() |
Source (recombinant) | Organism: ![]() ![]() |
Buffer solution | pH: 7.5 |
Specimen | Conc.: 1.8 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Vitrification | Cryogen name: ETHANE |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 2200 nm / Nominal defocus min: 1200 nm |
Image recording | Electron dose: 50 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) |
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Processing
CTF correction | Type: PHASE FLIPPING ONLY | ||||||||||||||||||||||||
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3D reconstruction | Resolution: 3.1 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 230158 / Symmetry type: POINT | ||||||||||||||||||||||||
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