6K4Y

CryoEM structure of sigma appropriation complex

Summary for 6K4Y

• Entry DOI: 10.2210/pdb6k4y/pdb
• EMDB information: 9916
• Descriptor: DNA-directed RNA polymerase subunit alpha, MAGNESIUM ION, ZINC ION, ... (11 entities in total)
• Functional Keywords: rna polymerase, sigma appropriation, transcription activation, promoter, transcription
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 10
• Total formula weight: 533593.50

Authors

Shi, J.,Wen, A.,Feng, Y. (deposition date: 2019-05-27, release date: 2019-08-07, Last modification date: 2024-03-27)

Primary citation

Shi, J.,Wen, A.,Zhao, M.,You, L.,Zhang, Y.,Feng, Y.
Structural basis of sigma appropriation.
Nucleic Acids Res., 47:9423-9432, 2019

PubMed Abstract: Bacteriophage T4 middle promoters are activated through a process called σ appropriation, which requires the concerted effort of two T4-encoded transcription factors: AsiA and MotA. Despite extensive biochemical and genetic analyses, puzzle remains, in part, because of a lack of precise structural information for σ appropriation complex. Here, we report a single-particle cryo-electron microscopy (cryo-EM) structure of an intact σ appropriation complex, comprising AsiA, MotA, Escherichia coli RNA polymerase (RNAP), σ70 and a T4 middle promoter. As expected, AsiA binds to and remodels σ region 4 to prevent its contact with host promoters. Unexpectedly, AsiA undergoes a large conformational change, takes over the job of σ region 4 and provides an anchor point for the upstream double-stranded DNA. Because σ region 4 is conserved among bacteria, other transcription factors may use the same strategy to alter the landscape of transcription immediately. Together, the structure provides a foundation for understanding σ appropriation and transcription activation.

PubMed: 31392983
DOI: 10.1093/nar/gkz682

Experimental method

ELECTRON MICROSCOPY (3.79 Å)