8h3v
Cryo-EM structure of the full transcription activation complex NtcA-NtcB-TACCryo-EM structure of the full transcription activation complex NtcA-NtcB-TAC
Structural highlights
FunctionRPOB_NOSS1 DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01321] Publication Abstract from PubMedTranscription factors respond to multilevel stimuli and co-occupy promoter regions of target genes to activate RNA polymerase (RNAP) in a cooperative manner. To decipher the molecular mechanism, here we report two cryo-electron microscopy structures of Anabaena transcription activation complexes (TACs): NtcA-TAC composed of RNAP holoenzyme, promoter and a global activator NtcA, and NtcA-NtcB-TAC comprising an extra context-specific regulator, NtcB. Structural analysis showed that NtcA binding makes the promoter DNA bend by approximately 50 degrees , which facilitates RNAP to contact NtcB at the distal upstream NtcB box. The sequential binding of NtcA and NtcB induces looping back of promoter DNA towards RNAP, enabling the assembly of a fully activated TAC bound with two activators. Together with biochemical assays, we propose a 'DNA looping' mechanism of cooperative transcription activation in bacteria. DNA looping mediates cooperative transcription activation.,Han SJ, Jiang YL, You LL, Shen LQ, Wu X, Yang F, Cui N, Kong WW, Sun H, Zhou K, Meng HC, Chen ZP, Chen Y, Zhang Y, Zhou CZ Nat Struct Mol Biol. 2024 Feb;31(2):293-299. doi: 10.1038/s41594-023-01149-7. , Epub 2024 Jan 4. PMID:38177666[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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