Project description:The bacterium, Francisella tularensis (Ft), is one of the most infectious agents known and classified as a category A bioweapon. Ft virulence is controlled by a unique set of transcription regulators, the MglA-SspA heterodimer, PigR, and the stress signal, ppGpp. These factors activate Francisella pathogenicity island (FPI) gene expression, which is required for virulence. MglA-SspA is expressed during infection and constitutively associates with the σ70 associated RNAP holoenzyme (RNAPσ70), indicating that RNAPσ70-(MglA-SspA) is a virulence specific polymerase. How virulence activation is mediated by these components, however, is unknown. Here we report cryo-EM structures of FtRNAPσ70, FtRNAPσ70-(MglA-SspA) and RNAPσ70-(MglA-SspA)-ppGpp-PigR complexes with promoter DNA. FtRNAPσ70-DNA and FtRNAPσ70-(MglA-SspA)-DNA structures and RT-PCR analyses show MglA-SspA stabilizes σ70 binding to DNA to regulate FPI-independent, virulence-enhancing genes. Strikingly, an Escherichia coli RNAPσ70 complex with EcSspA suggests this is a general mechanism for SspA-like regulation of bacterial RNAPσ70. Finally, our FtRNAP-σ70-(MglA-SspA)-ppGpp-PigR-DNA structure reveals that ppGpp binds to MglA-SspA to tether the DNA-binding activator, PigR, to FPI promoters. PigR in turn recruits FtRNAP CTDs to two DNA upstream (UP) elements, generating stable FPI transcription complexes. Thus, these studies unveil a novel paradigm for pathogenesis in Ft involving a virulence-specific RNAP that employs two (MglA-SspA)-based strategies to activate virulence genes.
Project description:Treatment of mouse skin with the staphylococcal protease SspA and house dust mite extract (HDM) results in dermatitis. Using a 10x Genomics scRNA-seq platform, we analyzed T cells isolated from inflamed skin after treatment with epicutaneous SspA and HDM.
Project description:Treatment of mouse skin with the staphylococcal protease SspA and house dust mite extract (HDM) results in dermatitis. Using a 10x Genomics Xenium In Situ platform, we analyzed spatial features in mock-treated skin and inflamed skin treated with epicutaneous SspA and HDM.
Project description:We performed RNA sequencing of Calu-3 cells after treatment with the BET-domain inhibitors JQ-1 and ABBV-744 as well as BRD2 CRISPRi knockdown. We also included CRISPRi knockdown of two other validated hit genes from our screen, COMP and ACE2.
Project description:To nominate identify tissues relevant to the etiology of bone mineral density we generated ATAC-seq in pediatric hMSC-osteoblasts, hFOB 1.19 cells (hFOBs), osteoclasts, and primary chondrocytes. Leveraging the results of this experiment, we designed a CRISPRi screen in hFOBs with scRNA-seq expression read out. The targets selected for the screen were informed by newly generated Capture-C and bulk RNA-seq from hFOBs.