@article{Cantlay_Haggerty_Horzempa_2021, title={OpiA, a Type Six Secretion System Substrate, localizes to the cell pole and plays a role in bacterial growth and viability in Francisella tularensis LVS.}, volume={93}, url={https://pwvas.org/index.php/pwvas/article/view/806}, DOI={10.55632/pwvas.v93i1.806}, abstractNote={<p><em>Francisella tularensis</em> is an intracellular pathogen and the causative agent of tularemia. The <em>F. tularensis</em> type six secretion system (T6SS) is required for a number of host-pathogen interactions including phagolysosomal escape and invasion of erythrocytes. </p><p>   One known effector of the T6SS, OpiA, has recently been shown to be a phosphatidylinositol-3 kinase. To investigate the role of OpiA in erythrocyte invasion, we constructed an <em>opiA</em>-null mutant in the live vaccine strain, <em>F. tularensis</em> LVS. OpiA was not required for erythrocyte invasion, however, deletion of <em>opiA</em> affected growth of <em>F. tularensis</em> LVS in broth cultures in a medium-dependent manner. </p><p>   We also found that <em>opiA</em> influenced cell size, gentamicin sensitivity, bacterial viability, and the lipid content of<em> F. tularensis</em>.  A fluorescently tagged OpiA (OpiA-EmGFP) accumulated at the cell poles of <em>F. tularensis </em>which is consistent with the location of the T6SS.  However, OpiA-EmGFP also exhibited a highly dynamic localization and this fusion protein was detected in erythrocytes and THP-1 cells <em>in vitro</em> further supporting that OpiA is secreted. Similar to previous reports using <em>F. novicida</em>, our data demonstrated that <em>opiA</em> had a minimal effect on intracellular replication of <em>F. tularensis</em> in host immune cells <em>in vitro</em>. However, THP-1 cells infected with the <em>opiA</em> mutant produced modestly (but significantly) higher levels of the pro-inflammatory cytokine TNF-α compared to these host cells infected with wild-type bacteria.</p><p>   Together, our results support previous observations that implicate <em>opiA</em> in infection and virulence, but also reveal an additional role for<em> opiA</em> central to the biology of <em>F. tularensis </em>bacteria.<em> </em>(This research was made possible by NASA West Virginia Space Grant Consortium Training Grant #NNX15A101H and by NIH Grant P20GM103434 to the West Virginia IDeA Network for Biomedical Research Excellence).</p>}, number={1}, journal={Proceedings of the West Virginia Academy of Science}, author={Cantlay, Stuart and Haggerty, Kristen and Horzempa, Joseph}, year={2021}, month={Apr.} }