6eu0
RNA Polymerase III open pre-initiation complex (OC-PIC)
Structural highlights
Function[RPAC2_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common core component of RNA polymerases I and III which synthesize ribosomal RNA precursors and small RNAs, such as 5S rRNA and tRNAs, respectively. [TBP_YEAST] General transcription factor that functions at the core of the DNA-binding general transcription factor complex TFIID. Binding of TFIID to a promoter (with or without TATA element) is the initial step in preinitiation complex (PIC) formation. TFIID plays a key role in the regulation of gene expression by RNA polymerase II through different activities such as transcription activator interaction, core promoter recognition and selectivity, TFIIA and TFIIB interaction, chromatin modification (histone acetylation by TAF1), facilitation of DNA opening and initiation of transcription.[1] [2] [3] [RPC8_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNA. The RPC25/RPC8-RPC17/RPC9 subcomplex may bind Pol III transcripts emerging from the adjacent exit pore during elongation. [RPC2_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Second largest core component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Proposed to contribute to the polymerase catalytic activity and forms the polymerase active center together with the largest subunit. Pol III is composed of mobile elements and RPC2 is part of the core element with the central large cleft and probably a clamp element that moves to open and close the cleft (By similarity). [RPC7_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. C31 is involved in the formation of the initiation complex. [TF3B_YEAST] General activator of RNA polymerase III transcription. Interacts with TBP. Binds to Pol III subunit C34 and to the TAU135 component of TFIIIC. [RPC1_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Largest and catalytic core component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Forms the polymerase active center together with the second largest subunit. A single-stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol III. A bridging helix emanates from RPC1 and crosses the cleft near the catalytic site and is thought to promote translocation of Pol III by acting as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations at each step of nucleotide addition (By similarity). [RPC5_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. The RPC53/RPC4-RPC37/RPC5 subcomplex is required for terminator recognition and reinitiation.[4] [RPC6_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Involved in recruitment of Pol III to the preinitiation complex. Involved in the configuration of an initiation-competent form of RNA polymerase.[5] [RPAB2_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and small RNAs, such as 5S rRNA and tRNAs, respectively. Pol II is the central component of the basal RNA polymerase II transcription machinery. Pols are composed of mobile elements that move relative to each other. In Pol II, RPB6 is part of the clamp element and togther with parts of RPB1 and RPB2 forms a pocket to which the RPB4-RPB7 subcomplex binds (By similarity). [RPAC1_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I and III which synthesize ribosomal RNA precursors and small RNAs, such as 5S rRNA and tRNAs, respectively. RPAC1 is part of the Pol core element with the central large cleft and probably a clamp element that moves to open and close the cleft (By similarity). [RPC10_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Involved in Pol III transcription reinitiation and RNA cleavage during transcription termination. [RPAB4_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and a small RNAs, such as 5S rRNA and tRNAs, respectively. Pols are composed of mobile elements that move relative to each other. In Pol II, the core element with the central large cleft comprises RPB3, RBP10, RPB11, RPB12 and regions of RPB1 and RPB2 forming the active center. [RPC4_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Essential for tRNA synthesis. The RPC53/RPC4-RPC37/RPC5 subcomplex is required for terminator recognition and reinitiation.[6] [RPC3_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific core component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. [TFC5_YEAST] General activator of RNA polymerase III transcription. [RPAB3_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and small RNAs, such as 5S rRNA and tRNAs, respectively. [RPC9_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Specific peripheric component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. The RPC25/RPC8-RPC17/RPC9 subcomplex may bind Pol III transcripts emerging from the adjacent exit pore during elongation. [RPAB5_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and a small RNAs, such as 5S rRNA and tRNAs, respectively. Pol II is the central component of the basal RNA polymerase II transcription machinery. Pols are composed of mobile elements that move relative to each other. In Pol II, RBP10 is part of the core element with the central large cleft. [RPAB1_YEAST] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Common component of RNA polymerases I, II and III which synthesize ribosomal RNA precursors, mRNA precursors and many functional non-coding RNAs, and small RNAs, such as 5S rRNA and tRNAs, respectively. Pol II is the central component of the basal RNA polymerase II transcription machinery. Pols are composed of mobile elements that move relative to each other. In Pol II, RPB5 is part of the lower jaw surrounding the central large cleft and thought to grab the incoming DNA template. Seems to be the major component in this process (By similarity). Publication Abstract from PubMedRNA polymerase (Pol) III transcribes essential non-coding RNAs, including the entire pool of transfer RNAs, the 5S ribosomal RNA and the U6 spliceosomal RNA, and is often deregulated in cancer cells. The initiation of gene transcription by Pol III requires the activity of the transcription factor TFIIIB to form a transcriptionally active Pol III preinitiation complex (PIC). Here we present electron microscopy reconstructions of Pol III PICs at 3.4-4.0 A and a reconstruction of unbound apo-Pol III at 3.1 A. TFIIIB fully encircles the DNA and restructures Pol III. In particular, binding of the TFIIIB subunit Bdp1 rearranges the Pol III-specific subunits C37 and C34, thereby promoting DNA opening. The unwound DNA directly contacts both sides of the Pol III cleft. Topologically, the Pol III PIC resembles the Pol II PIC, whereas the Pol I PIC is more divergent. The structures presented unravel the molecular mechanisms underlying the first steps of Pol III transcription and also the general conserved mechanisms of gene transcription initiation. Structural basis of RNA polymerase III transcription initiation.,Abascal-Palacios G, Ramsay EP, Beuron F, Morris E, Vannini A Nature. 2018 Jan 17;553(7688):301-306. doi: 10.1038/nature25441. PMID:29345637[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also
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