Structural highlights
Function
RPOA_ECOLI DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. This subunit plays an important role in subunit assembly since its dimerization is the first step in the sequential assembly of subunits to form the holoenzyme.[HAMAP-Rule:MF_00059]
Publication Abstract from PubMed
Bacterial transcription initiation requires sigma factors for nucleation of the transcription bubble. The canonical housekeeping sigma factor, sigma(70), nucleates DNA melting via recognition of conserved bases of the promoter -10 motif, which are unstacked and captured in pockets of sigma(70). By contrast, the mechanism of transcription bubble nucleation and formation during the unrelated sigma(N)-mediated transcription initiation is poorly understood. Herein, we combine structural and biochemical approaches to establish that sigma(N), like sigma(70), captures a flipped, unstacked base in a pocket formed between its N-terminal region I (RI) and extra-long helix features. Strikingly, RI inserts into the nascent bubble to stabilize the nucleated bubble prior to engagement of the obligate ATPase activator. Our data suggest a general paradigm of transcription initiation that requires sigma factors to nucleate an early melted intermediate prior to productive RNA synthesis.
A general mechanism for transcription bubble nucleation in bacteria.,Mueller AU, Chen J, Wu M, Chiu C, Nixon BT, Campbell EA, Darst SA Proc Natl Acad Sci U S A. 2023 Apr 4;120(14):e2220874120. doi: , 10.1073/pnas.2220874120. Epub 2023 Mar 27. PMID:36972428[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Mueller AU, Chen J, Wu M, Chiu C, Nixon BT, Campbell EA, Darst SA. A general mechanism for transcription bubble nucleation in bacteria. Proc Natl Acad Sci U S A. 2023 Apr 4;120(14):e2220874120. PMID:36972428 doi:10.1073/pnas.2220874120
