1. Extracellular life style of an intracellular pathogen
Volkan K. Köseoğlu
Postdoctoral Research Associate (Agaisse Laboratory)
Agaisse Laboratory: School of Medicine
Gahlmann Laboratory: College and Graduate School of Arts & Sciences
Ai Laboratory: School of Medicine
5/19/2019

2. Shigella spp. are intracellular bacterial pathogens
Shigella infections: Bacillary dysentery
Molecular basis of dissemination
Bloody diarrhea (Children < 5 yo)
Person-to-Person contact
Contaminated food and water
Shigella v
Actin tail
IcsA
Intracellular life cycle
in the colon
IcsA is essential for Shigella pathogenicity

3. A new extracellular role for IcsA IcsA secretion in ShigellaIM OM
Bacterial
cytoplasm
Extracellular environment
Actin-based motility
Intracellular niche
in cells
Bile salts-mediated
biofilm formation
Extracellular niche
in gut lumen

4. The defect of icsA is rescued by IcsA expression
IcsA is required for bile salts-mediated biofilm formation XY YZ WT
icsA
icsA pIcsA-Myc XZ
Scale bare: 20µm
Each symbol represents the average biofilm thickness of the 25 fields from each biological replicate (N=3).
Köseoğlu et al (2019) Infection and Immunity

5. How does IcsA promote static biofilm formation?
IcsA localization in static biofilms
Merged
Shigella + IcsA
IcsA
Shigella
Scale bare: 4 µm
Scale bare: 1 µm
Köseoğlu et al (2019) Infection and Immunity

6. Biofilm formation may facilitate colon colonization
Cholate
(small intestine)
Deoxycholate
(colon) XY YZ XZ
Köseoğlu et al (2019) Infection and Immunity

7. Does Shigella develop biofilm under flow?
How does IcsA promote biofilm formation under flow?
Collaborative study between
Agaisse Lab
Gahlmann Lab
Ai Lab

8. Medium flow Does Shigella develop biofilm under flow?
Biofilm formation under flow (Gahlmann Lab)
Simulation of gut movement
Is IcsA involved in this biofilm?
Shigella biofilm / Phase contrast imaging
Watching biofilm development in 3D
Medium flow
Bile salts-mediated Shigella biofilm in a flow channel (1 ml/h)
PhD students Mingxing and Gahlmann Lab
Lattice light sheet microscopy
E. coli biofilm under flow

9. How does IcsA promote biofilm formation under flow?
Visualizing IcsA during live imaging (Ai Lab)
Detecting IcsA and Shigella during biofilm formation
Construction of IcsA variants
Incubation with probe during biofilm formation
Shigella
IcsA IM OM
Bacterial
cytoplasm
Extracellular environment
Shigella
IcsA
Fluorescent probe
PhD Student Ai Lab

10. Main outcomes of the collaboration
Conclusion
Main outcomes of the collaboration
Shigella forms biofilm under flow
Created construct for live imaging of IcsA
Significance
Bile salts-mediated
Shigella biofilms
Gut colonization
Diarrhea
Asymptomatic carriage

11. Acknowledgements Hervé Agaisse Gahlmann Lab Ai Lab
Mingxing Zhang
Ji Zhang
Ai Lab
Tianchen Wu
Funding: NIH NIAID (R01AI073904)
3 Cavaliers (GIDI)