8DY7

Streptomyces venezuelae RNAP transcription open promoter complex with WhiA and WhiB transcription factors

Summary for 8DY7

• Entry DOI: 10.2210/pdb8dy7/pdb
• EMDB information: 27777
• Descriptor: DNA-directed RNA polymerase subunit alpha, DNA (71-MER), ZINC ION, ... (13 entities in total)
• Functional Keywords: rna polymerase, transcription factor, iron cluster, transcription-transferase-dna complex, transcription/transferase/dna
• Biological source: Streptomyces venezuelae; More
• Total number of polymer chains: 11
• Total formula weight: 539348.41

Authors

Lilic, M.,Campbell, E.A. (deposition date: 2022-08-03, release date: 2023-03-01, Last modification date: 2025-05-21)

Primary citation

Lilic, M.,Holmes, N.A.,Bush, M.J.,Marti, A.K.,Widdick, D.A.,Findlay, K.C.,Choi, Y.J.,Froom, R.,Koh, S.,Buttner, M.J.,Campbell, E.A.
Structural basis of dual activation of cell division by the actinobacterial transcription factors WhiA and WhiB.
Proc.Natl.Acad.Sci.USA, 120:e2220785120-e2220785120, 2023

PubMed Abstract: Studies of transcriptional initiation in different bacterial clades reveal diverse molecular mechanisms regulating this first step in gene expression. The WhiA and WhiB factors are both required to express cell division genes in Actinobacteria and are essential in notable pathogens such as . The WhiA/B regulons and binding sites have been elucidated in (), where they coordinate to activate sporulation septation. However, how these factors cooperate at the molecular level is not understood. Here we present cryoelectron microscopy structures of transcriptional regulatory complexes comprising RNA polymerase (RNAP) σ-holoenzyme and WhiA and WhiB, in complex with the WhiA/B target promoter . These structures reveal that WhiB binds to domain 4 of σ (σ) of the σ-holoenzyme, bridging an interaction with WhiA while making non-specific contacts with the DNA upstream of the -35 core promoter element. The N-terminal homing endonuclease-like domain of WhiA interacts with WhiB, while the WhiA C-terminal domain (WhiA-CTD) makes base-specific contacts with the conserved WhiA GACAC motif. Notably, the structure of the WhiA-CTD and its interactions with the WhiA motif are strikingly similar to those observed between σ housekeeping σ-factors and the -35 promoter element, suggesting an evolutionary relationship. Structure-guided mutagenesis designed to disrupt these protein-DNA interactions reduces or abolishes developmental cell division in confirming their significance. Finally, we compare the architecture of the WhiA/B σ-holoenzyme promoter complex with the unrelated but model CAP Class I and Class II complexes, showing that WhiA/WhiB represent a new mechanism in bacterial transcriptional activation.

PubMed: 36888660
DOI: 10.1073/pnas.2220785120

Experimental method

ELECTRON MICROSCOPY (3.18 Å)