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My research projects aim at understanding how living organisms acquire and maintain their shape. For this, I am studying Bacillus subtilis a well-known bacterial model that keep a very constant rod shaped along generations, and in particular how these cells build their envelop, the cell wall. This wall forms a protective, rigid structure outside of the cell, and constitutes the major physical determinant of the shape in bacteria. It is also, as an essential component, a major target for antimicrobial drugs.
To gain insight into this process, I am studying the cell wall synthetic machineries and more specifically the role of bacterial actin homologues (MreB), essential proteins that form mobile polymers with complex dynamics. These studies need a panel of approaches including molecular genetics, biochemistry and super-resolution microscopy (TIRF, SIM, PALM, SPT).
The current projects include:

• super-rez microscopic approaches (SIM-TIRF, PALM) to characterize in vivo the dynamic properties and structures of MreB complexes.
• in vitro characterization of the biochemical properties of B. subtilis MreB (using identified mutants from a previous screen)
• screenings (suppressor mutants, partners of MreB, inhibitors of MreBs, cell shape determinants…)

22. Hamouche L, Billaudeau C, Rocca A, Chastanet A, Ngo S, Laalami S, Putzer H. Dynamic Membrane Localization of RNase Y in Bacillus subtilis. mBio. 2020 Feb 18;11(1):e03337-19. doi: 10.1128/mBio.03337-19.

21. Billaudeau C, Chastanet A, Carballido-López R. Processing TIRF Microscopy Images to Characterize the Dynamics and Morphology of Bacterial Actin-Like Assemblies. Methods Mol Biol. 2020 Jan; 2101:135-145. doi: 10.1007/978-1-0716-0219-5_9.

20. Cornilleau C, Chastanet A, Billaudeau C, Carballido-López R. Methods for Studying Membrane-Associated Bacterial Cytoskeleton Proteins In Vivo by TIRF Microscopy. Methods Mol Biol. 2020 Jan; 2101:123-133. doi: 10.1007/978-1-0716-0219-5_8.

19. Billaudeau C, Yao Z, Cornilleau C, Carballido-Lopez R, Chastanet A. MreB Forms Subdiffraction Nanofilaments during Active Growth in Bacillus subtilis. MBio. 2019 Jan 29; doi: 10.1128/mBio.01879-18.

18. Krokowski S, Lobato-Márquez D, Chastanet A, Pereira PM, Angelis D, Galea D, Larrouy-Maumus G, Henriques R, Spiliotis ET, Carballido-López R, Mostowy S. Septins Recognize and Entrap Dividing Bacterial Cells for Delivery to Lysosomes. Cell Host Microbe. 2018 Dec 12; doi: 10.1016/j.chom.2018.11.005.

17. De San Eustaquio-Campillo A, Cornilleau C, Guérin C, Carballido-López R and Chastanet A. “PamR, a new MarR-like regulator affecting prophages and metabolic genes expression in Bacillus subtilis.” PLoS ONE. 2017. Dec 14; 12(12): e0189694. Doi: 10.1371/journal.pone.0189694.

16. Billaudeau C*, Chastanet A*, Yao Z*, Cornilleau C, Mirouze N, Fromion V and Carballido-Lopez R. “Contrasting mechanisms of growth in two model rod-shaped bacteria.” Nat. Comms. 2017, Jun; DOI: 10.1038/ncomms15370.

15. Mirouze N, Ferret C, Yao Z, Chastanet A, Carballido-López R. “MreB-Dependent Inhibition of Cell Elongation during the Escape from Competence in Bacillus subtilis”. PLoS Genet. 2015 Jun 19;11(6): e1005299.

14. Rueff AS*, Chastanet A*, Dominguez-Escobar J, Yao Z, Yates J, Prejean M-V, Delumeau O, Noirot P, Wedlich-Soldner R, Filipe SR, and Carballido-Lopez R. “An early cytoplasmic step of peptidoglycan synthesis is associated to MreB in Bacillus subtilis.” Mol. Microbiol. 2014, Jan; 91(2):348-62.

13. Chastanet A and Carballido-Lopez R. “The actin-like MreB proteins in Bacillus subtilis: a new turn.” Front Biosci (Schol Ed.) 2012, Jun 1;4:1582-606.

12. Dominguez-Escobar J, Chastanet A*, Crevenna AH*, Fromion V, Wedlich-Soldner R, Carballido-Lopez R. “Processive movement of MreB-associated cell-wall biosynthetic complexes in bacteria”. Science 2011, 333; 225 - 228

11. Chastanet A and Losick R. “Just-in-time control of Spo0A synthesis in Bacillus subtilis by multiple regulatory mechanisms”. J Bacteriol. 2011, 193(22):6366-74

10. Chastanet A, Vitkup D, Yuan GC, Norman TM, Liu JS, Losick RM. “Broadly heterogenous activation of the master regulator for sporulation in Bacillus subtilis”. Proc. Natl. Acad. Sci. USA. 2010;May 4;107(18):8486-91

9. Banse AV, Chastanet A, Rahn-Lee L, Hobbs EC, Losick R. “Parallel pathways of repression and antirepression governing the transition to stationary phase in Bacillus subtilis.” Proc. Natl. Acad. Sci. USA. 2008;105(40):15547-52.

8. Chastanet A and Losick. R. "Engulfment during sporulation in Bacillus subtilis is governed by a multi-protein complex containing tandemly acting autolysins". Mol. Microbiol. 2007 64:139-52.

7. Arnaud M, Chastanet A and Débarbouillé M. "New vector for efficient allelic replacement in naturally non-transformable, low-GC-content, Gram-positive bacteria". Appl Environ Microbiol. 2004 70: 6887-91.

6. Frees D, Chastanet A, Qazi S, Sorensen K, Hill P, Msadek T and Ingmer H. "Clp ATPases are required for stress tolerance, intracellular replication and biofilm formation in Staphylococcus aureus". Mol. Microbiol. 2004 54:1445-62.

5. Chastanet A, Derré I, Nair S and Msadek T. "clpB, a novel member of the Listeria monocytogenes CtsR regulon, is involved in virulence but not in general stress tolerance". J. Bacteriol. 2004 186:1165-1174

4. Chastanet A, Fert J and Msadek T. "Comparative genomics reveal novel heat shock regulatory mechanisms in Staphylococcus aureus and other Gram positive bacteria". Mol. Microbiol. 2003 47:1061-73.

3. Chastanet A, Msadek T. "clpP of Streptococcus salivarius is a novel member of the dually regulated class of stress response genes in Gram-positive bacteria". J Bacteriol. 2003 185:683-87

2. Chastanet A, Prudhomme M, Claverys JP, Msadek T. "Regulation of Streptococcus pneumoniae clp genes and their role in competence development and stress survival". J Bacteriol. 2001 183:7295-307.

1. Venderbure C, Chastanet A, Boudsocq F, Sommer S, Bailone A. "Inhibition of homologous recombination by the plasmid MucA'B complex". J Bacteriol. 1999 181:1249-55.

(* authors contributed equally to the work).

Since high school, it was always clear for me I will be a researcher (even though some of my professors seem to disagree with this idea!). I seriously doubted only once, right before grad school, but from this point it has been a clear and very enjoyable path to follow.
I did my PhD at “the Pasteur” in Paris where I was studying the stress response in various Gram-positive bacteria. After my graduation in 2003, I moved to Boston USA, for a 5 years postdoc in Rich Losick lab in Harvard. The whole process was a terrific experience, both scientifically and personally.
Looking for a project in the bacterial development field, I moved back to France in 2009, at the national institute for agronomical research (INRA), close to Paris, and joined Rut Carballido-Lopez team, where I obtained a full position in 2012. I am currently leading a couple projects involving 4 people from our group.