6WMP

F. tularensis RNAPs70-iglA DNA complex

Summary for 6WMP

• Entry DOI: 10.2210/pdb6wmp/pdb
• EMDB information: 21850
• Descriptor: DNA-directed RNA polymerase subunit alpha 1, ZINC ION, DNA-directed RNA polymerase subunit alpha 2, ... (10 entities in total)
• Functional Keywords: rna polymerase complex, transcription
• Biological source: Francisella tularensis subsp. holarctica (strain LVS); More
• Total number of polymer chains: 8
• Total formula weight: 423380.85

Authors

Travis, B.A.,Brennan, R.G.,Schumacher, M.A. (deposition date: 2020-04-21, release date: 2020-11-11, Last modification date: 2024-03-06)

Primary citation

Travis, B.A.,Ramsey, K.M.,Prezioso, S.M.,Tallo, T.,Wandzilak, J.M.,Hsu, A.,Borgnia, M.,Bartesaghi, A.,Dove, S.L.,Brennan, R.G.,Schumacher, M.A.
Structural Basis for Virulence Activation of Francisella tularensis.
Mol.Cell, 81:139-, 2021

PubMed Abstract: The bacterium Francisella tularensis (Ft) is one of the most infectious agents known. Ft virulence is controlled by a unique combination of transcription regulators: the MglA-SspA heterodimer, PigR, and the stress signal, ppGpp. MglA-SspA assembles with the σ-associated RNAP holoenzyme (RNAPσ), forming a virulence-specialized polymerase. These factors activate Francisella pathogenicity island (FPI) gene expression, which is required for virulence, but the mechanism is unknown. Here we report FtRNAPσ-promoter-DNA, FtRNAPσ-(MglA-SspA)-promoter DNA, and FtRNAPσ-(MglA-SspA)-ppGpp-PigR-promoter DNA cryo-EM structures. Structural and genetic analyses show MglA-SspA facilitates σ binding to DNA to regulate virulence and virulence-enhancing genes. Our Escherichia coli RNAPσhomodimeric EcSspA structure suggests this is a general SspA-transcription regulation mechanism. Strikingly, our FtRNAPσ-(MglA-SspA)-ppGpp-PigR-DNA structure reveals ppGpp binding to MglA-SspA tethers PigR to promoters. PigR in turn recruits FtRNAP αCTDs to DNA UP elements. Thus, these studies unveil a unique mechanism for Ft pathogenesis involving a virulence-specialized RNAP that employs two (MglA-SspA)-based strategies to activate virulence genes.

PubMed: 33217319
DOI: 10.1016/j.molcel.2020.10.035

Experimental method

ELECTRON MICROSCOPY (2.98 Å)