5tmc
From Proteopedia
Re-refinement of Thermus thermopiles DNA-directed RNA polymerase structure
Structural highlights
Function[RPOZ_THET2] 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. [RPOA_THETH] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. [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. [SIGA_THET2] 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.[HAMAP-Rule:MF_00963] Publication Abstract from PubMedGuanosine-tetraphosphate (ppGpp) is a major regulator of stringent control, an adaptive response of bacteria to amino acid starvation. The 2.7 A resolution structure of the Thermus thermophilus RNA polymerase (RNAP) holoenzyme in complex with ppGpp reveals that ppGpp binds to the same site near the active center in both independent RNAP molecules in the crystal but in strikingly distinct orientations. Binding is symmetrical with respect to the two diphosphates of ppGpp and is relaxed with respect to the orientation of the nucleotide base. Different modes of ppGpp binding are coupled with asymmetry of the active site configurations. The results suggest that base pairing of ppGpp with cytosines in the nontemplate DNA strand might be an essential component of transcription control by ppGpp. We present experimental evidence highlighting the importance of base-specific contacts between ppGpp and specific cytosine residues during both transcription initiation and elongation. Structural basis for transcription regulation by alarmone ppGpp.,Artsimovitch I, Patlan V, Sekine S, Vassylyeva MN, Hosaka T, Ochi K, Yokoyama S, Vassylyev DG Cell. 2004 Apr 30;117(3):299-310. PMID:15109491[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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