8H3V

Cryo-EM structure of the full transcription activation complex NtcA-NtcB-TAC

Summary for 8H3V

• Entry DOI: 10.2210/pdb8h3v/pdb
• EMDB information: 34475
• Descriptor: DNA (125-MER), NtcA, DNA-directed RNA polymerase subunit beta, ... (10 entities in total)
• Functional Keywords: transcription activation complex, coordinated regulation, transcription
• Biological source: Anabaena; More
• Total number of polymer chains: 15
• Total formula weight: 718729.42

Authors

Han, S.J.,Jiang, Y.L.,You, L.L.,Shen, L.Q.,Wu, X.X.,Yang, F.,Kong, W.W.,Chen, Z.P.,Zhang, Y.,Zhou, C.Z. (deposition date: 2022-10-09, release date: 2023-10-04, Last modification date: 2024-10-30)

Primary citation

Han, S.J.,Jiang, Y.L.,You, L.L.,Shen, L.Q.,Wu, X.,Yang, F.,Cui, N.,Kong, W.W.,Sun, H.,Zhou, K.,Meng, H.C.,Chen, Z.P.,Chen, Y.,Zhang, Y.,Zhou, C.Z.
DNA looping mediates cooperative transcription activation.
Nat.Struct.Mol.Biol., 31:293-299, 2024

PubMed Abstract: Transcription 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 ∼50°, 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.

PubMed: 38177666
DOI: 10.1038/s41594-023-01149-7

Experimental method

ELECTRON MICROSCOPY (4.5 Å)