View source for 2pi4


==T7RNAP complexed with a phi10 protein and initiating GTPs.==
<StructureSection load='2pi4' size='340' side='right'caption='[[2pi4]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2pi4]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_phage_T7 Escherichia phage T7]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PI4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2PI4 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GH3:3-DEOXY-GUANOSINE-5-TRIPHOSPHATE'>GH3</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2pi4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2pi4 OCA], [https://pdbe.org/2pi4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2pi4 RCSB], [https://www.ebi.ac.uk/pdbsum/2pi4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2pi4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RPOL_BPT7 RPOL_BPT7] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Responsible for the transcription of the late genes of T7. It is rifampicin-resistant. It recognizes a specific promoter sequence, unwinds the double-stranded RNA to expose the coding strand for templating, initiates transcription preferentially with a purine.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/pi/2pi4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2pi4 ConSurf].
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<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
DNA-directed RNA polymerases are capable of initiating synthesis of RNA without primers, the first catalytic stage of initiation is referred to as de novo RNA synthesis. De novo synthesis is a unique phase in the transcription cycle where the RNA polymerase binds two nucleotides rather than a nascent RNA polymer and a single nucleotide. For bacteriophage T7 RNA polymerase, transcription begins with a marked preference for GTP at the +1 and +2 positions. We determined the crystal structures of T7 RNA polymerase complexes captured during the de novo RNA synthesis. The DNA substrates in the structures in the complexes contain a common Phi 10 duplex promoter followed by a unique five base single-stranded extension of template DNA whose sequences varied at positions +1 and +2, thereby allowing for different pairs of initiating nucleotides GTP, ATP, CTP or UTP to bind. The structures show that the initiating nucleotides bind RNA polymerase in locations distinct from those described previously for elongation complexes. Selection bias in favor of GTP as an initiating nucleotide is accomplished by shape complementarity, extensive protein side-chain and strong base-stacking interactions for the guanine moiety in the enzyme active site. Consequently, an initiating GTP provides the largest stabilization force for the open promoter conformation.

Mechanism for de novo RNA synthesis and initiating nucleotide specificity by t7 RNA polymerase.,Kennedy WP, Momand JR, Yin YW J Mol Biol. 2007 Jul 6;370(2):256-68. Epub 2007 Mar 21. PMID:17512007<ref>PMID:17512007</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2pi4" style="background-color:#fffaf0;"></div>

==See Also==
*[[RNA polymerase 3D structures|RNA polymerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia phage T7]]
[[Category: Large Structures]]
[[Category: Kennedy WP]]
[[Category: Momand JR]]
[[Category: Yin YW]]