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==Crystal structure of MTB sigma L transcription initiation complex with 5 nt long RNA primer==
<StructureSection load='6tye' size='340' side='right'caption='[[6tye]], [[Resolution|resolution]] 3.79&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6tye]] is a 9 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6TYE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6TYE FirstGlance]. <br>
</td></tr><tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/DNA-directed_RNA_polymerase DNA-directed RNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.6 2.7.7.6] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6tye FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6tye OCA], [http://pdbe.org/6tye PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6tye RCSB], [http://www.ebi.ac.uk/pdbsum/6tye PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6tye ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/RPOB_MYCTO RPOB_MYCTO]] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. [[http://www.uniprot.org/uniprot/A0A045H2R3_MYCTX A0A045H2R3_MYCTX]] Promotes RNA polymerase assembly. Latches the N- and C-terminal regions of the beta' subunit thereby facilitating its interaction with the beta and alpha subunits.[HAMAP-Rule:MF_00366][SAAS:SAAS00387808] [[http://www.uniprot.org/uniprot/RPOA_MYCTA RPOA_MYCTA]] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. 
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== Publication Abstract from PubMed ==
All organisms-bacteria, archaea, and eukaryotes-have a transcription initiation factor that contains a structural module that binds within the RNA polymerase (RNAP) active-center cleft and interacts with template-strand single-stranded DNA (ssDNA) in the immediate vicinity of the RNAP active center. This transcription initiation-factor structural module preorganizes template-strand ssDNA to engage the RNAP active center, thereby facilitating binding of initiating nucleotides and enabling transcription initiation from initiating mononucleotides. However, this transcription initiation-factor structural module occupies the path of nascent RNA and thus presumably must be displaced before or during initial transcription. Here, we report four sets of crystal structures of bacterial initially transcribing complexes that demonstrate and define details of stepwise, RNA-extension-driven displacement of the "sigma-finger" of the bacterial transcription initiation factor sigma. The structures reveal that-for both the primary sigma-factor and extracytoplasmic (ECF) sigma-factors, and for both 5'-triphosphate RNA and 5'-hydroxy RNA-the "sigma-finger" is displaced in stepwise fashion, progressively folding back upon itself, driven by collision with the RNA 5'-end, upon extension of nascent RNA from approximately 5 nt to approximately 10 nt.

RNA extension drives a stepwise displacement of an initiation-factor structural module in initial transcription.,Li L, Molodtsov V, Lin W, Ebright RH, Zhang Y Proc Natl Acad Sci U S A. 2020 Mar 3. pii: 1920747117. doi:, 10.1073/pnas.1920747117. PMID:32127479<ref>PMID:32127479</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6tye" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: DNA-directed RNA polymerase]]
[[Category: Large Structures]]
[[Category: Ebright, R H]]
[[Category: Molodtsov, V]]
[[Category: Initiation]]
[[Category: Sigma finger displacement]]
[[Category: Transcription]]
[[Category: Tuberculosis]]