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Anti-pausing activity of region 4 of the RNA polymerase σ subunit and its regulation by σ-remodeling factors
Link to bioRxiv paper:
http://biorxiv.org/cgi/content/short/2020.08.11.244855v1?rss=1
Authors: Brodolin, K., Morichaud, Z.
Abstract:
The basal transcription factors of cellular RNA polymerases (RNAPs) stimulate the initial RNA synthesis via poorly understood mechanisms. Here, we explored the mechanism employed by the bacterial factor {sigma} in promoter-independent initial transcription. We found that the RNAP holoenzyme lacking the promoter-binding domain {sigma}4 is ineffective in de novo transcription initiation and displays high propensity to pausing upon extension of RNAs 3 to 7 nucleotides in length. The {sigma}4 domain stabilizes short RNA:DNA hybrids and suppresses pausing by stimulating RNAP active-center translocation. The anti-pausing activity of {sigma}4 is modulated by its interaction with the {beta} subunit flap domain and by the {sigma} remodeling factors AsiA and RbpA. Our results suggest that the presence of {sigma}4 within the RNA exit channel compensates for the intrinsic instability of short RNA:DNA hybrids by increasing RNAP processivity, thus favoring productive transcription initiation. This RNAP boosting activity of the initiation factor is shaped by the the thermodynamics of RNA:DNA interactions and thus, should be relevant for any factor-dependent RNAP.
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Link to bioRxiv paper:
http://biorxiv.org/cgi/content/short/2020.08.11.244855v1?rss=1
Authors: Brodolin, K., Morichaud, Z.
Abstract:
The basal transcription factors of cellular RNA polymerases (RNAPs) stimulate the initial RNA synthesis via poorly understood mechanisms. Here, we explored the mechanism employed by the bacterial factor {sigma} in promoter-independent initial transcription. We found that the RNAP holoenzyme lacking the promoter-binding domain {sigma}4 is ineffective in de novo transcription initiation and displays high propensity to pausing upon extension of RNAs 3 to 7 nucleotides in length. The {sigma}4 domain stabilizes short RNA:DNA hybrids and suppresses pausing by stimulating RNAP active-center translocation. The anti-pausing activity of {sigma}4 is modulated by its interaction with the {beta} subunit flap domain and by the {sigma} remodeling factors AsiA and RbpA. Our results suggest that the presence of {sigma}4 within the RNA exit channel compensates for the intrinsic instability of short RNA:DNA hybrids by increasing RNAP processivity, thus favoring productive transcription initiation. This RNAP boosting activity of the initiation factor is shaped by the the thermodynamics of RNA:DNA interactions and thus, should be relevant for any factor-dependent RNAP.
Copy rights belong to original authors. Visit the link for more info