I am a Molecular Microbiologist interested in understanding the unique features of microorganisms notably the adaptive mechanisms of organisms living in extreme environments and more specifically how cells survive genomic stress.
My PhD research , In France, provided new insights into the role of specific genes in the DNA repair and the stress response mechanisms participating in the outstanding radio resistance of the bacterium Deinococcus radiodurans.
To explore further the diversity of microbial forms of life, I joined the team of A/Prof. Iain Duggin, to study the cell division mechanisms in the halophilis archaeon Haloferax volcanii.
Archaea for the 3rd Domain of life and are unique organisms that show some features in common with eukaryotes, including striking phylogenetic relatedness, notably in their cellular machineries, whereas their basic cellular layout resembles to bacteria. Basic research on archaea has led to major biotechnological innovations, including PCR and CRISPR technology, that have had vast impact in health and society. Hewever they remain poorly understood.
My Postdoctoral research focuses in characterizing the role of FtsZ homologue in cell division.
Can supervise: YES
- Microbial adaptaion to harsh environements
- Cell Division
- DNA metabolism
- Genome maintenance
- Genome segregation
- Stress response
Postdoctoral Research Associate
Chair of the Science PostDoc Association
Liao, Y, Ithurbide, S, Löwe, J & Duggin, IG 2020, 'Two FtsZ proteins orchestrate archaeal cell division through distinct functions in ring assembly and constriction', BioRxiv.View/Download from: Publisher's site
AbstractThe tubulin homolog FtsZ assembles a ring in bacteria and plays a key role in the machinery that constricts to divide the cells. Many archaea encode two FtsZs from distinct families, FtsZ1 and FtsZ2, of previously unclear functions. We show that Haloferax volcanii cannot divide properly without either or both but proliferates in alternative ways via remarkable envelope plasticity. The FtsZs co-localize as a dynamic midcell division ring. FtsZ1 independently assembles and stabilizes FtsZ2 in the ring, and influences cell shape, whereas FtsZ2 functions in the constriction mechanism; their GTPase active sites are crucial for these activities. The two FtsZs are widespread in archaea with a single S-layer envelope, but those with a pseudomurein wall only have FtsZ1. FtsZ2 appears to be essential for constriction of the flexible membrane-S-layer, where an internal constriction force might dominate the division mechanism in contrast to bacteria and archaea that divide by wall ingrowth.
Nußbaum, P, Ithurbide, S, Walsh, J, Patro, M, Delpech, F, Rodriguez-Franco, M, Curmi, PMG, Duggin, IG, Quax, TEF & Albers, S-V 2020, 'An oscillating MinD protein determines the cellular positioning of the motility machinery in archaea', BioRxiv.View/Download from: Publisher's site
MinD proteins are well studied in rod-shaped bacteria such as E. coli , where they display self-organized pole-to-pole oscillations that are important for correct positioning of the Z-ring at mid-cell for cell division. Archaea also encode proteins belonging to the MinD family, but their functions are unknown. MinD homologous proteins were found to be widespread in Euryarchaeota and form a sister group to the bacterial MinD family, distinct from the ParA and other related ATPase families. We aimed to identify the function of four archaeal MinD proteins in the model archaeon Haloferax volcanii . Deletion of the minD genes did not cause cell division or size defects, and the Z-ring was still correctly positioned. Instead, one of the mutations (Δ minD4 ) reduced swimming motility, and hampered the correct formation of motility machinery at the cell poles. In Δ minD4 cells, there is reduced formation of the motility structure and chemosensory arrays, which are essential for signal transduction. In bacteria, several members of the ParA family can position the motility structure and chemosensory arrays via binding to a landmark protein, and consequently these proteins do not oscillate along the cell axis. However, GFP-MinD4 displayed pole-to-pole oscillation and formed polar patches or foci in H. volcanii . The MinD4 membrane targeting sequence (MTS), homologous to the bacterial MinD MTS, was essential for the oscillation. Surprisingly, MinD4 ATPase domain point-mutations did not block oscillation, but they failed to form pole-patches. Thus, MinD4 from H. volcanii combines traits of different bacterial ParA/MinD proteins.
Liao, Y, Ithurbide, S, de Silva, RT, Erdmann, S & Duggin, IG 2018, 'Archaeal cell biology: diverse functions of tubulin-like cytoskeletal proteins at the cell envelope', Emerging Topics in Life Sciences, vol. 2, no. 4, pp. 547-559.View/Download from: Publisher's site
Devigne, A, Ithurbide, S, de la Tour, CB, Passot, F, Mathieu, M, Sommer, S & Servant, P 2015, 'DdrO is an essential protein that regulates the radiation desiccation response and the apoptotic-like cell death in the radioresistant Deinococcus radiodurans bacterium', MOLECULAR MICROBIOLOGY, vol. 96, no. 5, pp. 1069-1084.View/Download from: Publisher's site
Ithurbide, S, Bentchikou, E, Coste, G, Bost, B, Servant, P & Sommer, S 2015, 'Single Strand Annealing Plays a Major Role in RecA-Independent Recombination between Repeated Sequences in the Radioresistant Deinococcus radiodurans Bacterium', PLoS Genetics, vol. 11, no. 10.View/Download from: Publisher's site
Norais, C, Servant, P, Bouthier-de-la-Tour, C, Coureux, P-D, Ithurbide, S, Vannier, F, Guerin, PP, Dulberger, CL, Satyshur, KA, Keck, JL, Armengaud, J, Cox, MM & Sommer, S 2013, 'The Deinococcus radiodurans DR1245 Protein, a DdrB Partner Homologous to YbjN Proteins and Reminiscent of Type III Secretion System Chaperones', PLOS ONE, vol. 8, no. 2.View/Download from: Publisher's site
My Collaborations include :
- Harvard University, USA
- University of Freiburg, Germany