6l74 | pdb_00006l74
Thermus thermophilus initial transcription complex comprising sigma A and 5'-triphosphate RNA of 2 nt
Structural highlights
Function[RPOC_THET8] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. [RPOB_THET8] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. [RPOA_THET8] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. [RPOZ_THET8] 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 (By similarity). [Q5SKW1_THET8] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released (By similarity).[RuleBase:RU000715] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This sigma factor is the primary sigma factor during exponential growth (By similarity).[HAMAP-Rule:MF_00963] Publication Abstract from PubMedAll 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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