8GZG

Cryo-EM structure of Synechocystis sp. PCC 6803 RPitc

Summary for 8GZG

• Entry DOI: 10.2210/pdb8gzg/pdb
• EMDB information: 34397
• Descriptor: DNA-directed RNA polymerase subunit alpha, MAGNESIUM ION, ZINC ION, ... (11 entities in total)
• Functional Keywords: cryo-em, synechocystis sp. pcc 6803, syn6803, transcription initiation, rpitc, transcription, cyanobacteria, transcription-dna-rna complex, transcription/dna/rna
• Biological source: Synechocystis sp. PCC 6803; More
• Total number of polymer chains: 10
• Total formula weight: 515444.03

Authors

Shen, L.Q.,You, L.L.,Zhang, Y. (deposition date: 2022-09-27, release date: 2023-04-19, Last modification date: 2024-10-30)

Primary citation

Shen, L.,Lai, G.,You, L.,Shi, J.,Wu, X.,Puiu, M.,Gu, Z.,Feng, Y.,Yuzenkova, Y.,Zhang, Y.
An SI3-sigma arch stabilizes cyanobacteria transcription initiation complex.
Proc.Natl.Acad.Sci.USA, 120:e2219290120-e2219290120, 2023

PubMed Abstract: Multisubunit RNA polymerases (RNAPs) associate with initiation factors (σ in bacteria) to start transcription. The σ factors are responsible for recognizing and unwinding promoter DNA in all bacterial RNAPs. Here, we report two cryo-EM structures of cyanobacterial transcription initiation complexes at near-atomic resolutions. The structures show that cyanobacterial RNAP forms an "SI3-σ" arch interaction between domain 2 of σ (σ) and sequence insertion 3 (SI3) in the mobile catalytic domain Trigger Loop (TL). The "SI3-σ" arch facilitates transcription initiation from promoters of different classes through sealing the main cleft and thereby stabilizing the RNAP-promoter DNA open complex. Disruption of the "SI3-σ" arch disturbs cyanobacteria growth and stress response. Our study reports the structure of cyanobacterial RNAP and a unique mechanism for its transcription initiation. Our data suggest functional plasticity of SI3 and provide the foundation for further research into cyanobacterial and chloroplast transcription.

PubMed: 37036976
DOI: 10.1073/pnas.2219290120

Experimental method

ELECTRON MICROSCOPY (3.13 Å)