Cell cycle control in C.crescentus, an asymmetric bacterium
Using the polarised bacterium Caulobacter crescentus as a model system, we showed that the TipN polarity determinant, a membrane-anchored coiled coil protein, is inserted at the newborn pole as soon as it is manufactured (at cell division) to then recruit flagellum assembly factors at the pole predetermined for flagellation.
We also elucidated a mechanism of cell polarisation specific for the old pole that carries a stalk and subsequently unravelled a new cell bi-polarisation pathway, including a determinant for the assembly of polar pili. We fortuitously discovered that induction of an RND-type efflux pump by the quinolone antibiotic nalidixic acid, Nal, is more deleterious to cells lacking TipN compared to WT cells, rather than beneficial as typically seen.
We then found that the induction by Nal can be attenuated by activation of an RNAse toxin component of the toxin-antitoxin system, providing a compelling example of how a toxin can protect against the lethal action of Nal by cleaving the mRNA encoding the RND pump. Recently, chemical-genetics experiments revealed that the pump can also expel certain beta-lactam antibiotics and thus confer resistance independently of the metallo-beta-lactamase that confers resistance to beta-lactams in C. crescentus and its relatives.
SPECIFIC EXPERTISE
- Genetics, ChIP-Seq, TN-Seq, glycobiology, fluorescence microscopy, and antibiotic resistance
SELECTED PUBLICATIONS
Ardissone, S., N. Kint and P. H. Viollier (2020) . Elife 9:e60488. doi: 10.7554/eLife.60488.
Ardissone, S. N. Kint, B. Petrignani, G. Panis and P. H. Viollier (2020) . Dev Cell: 55(4):500-513.e4. doi: 10.1016/j.devcel.2020.10.005.
Kirkpatrick, C.L., D. Martins, P. Redder, A. Frandi, J. Mignolet, J. Bortoli Chapalay, M. Chambon and P.H. Viollier (2016). . Nature Microbiology, doi:10.1038/nmicrobiol.2016.8
Joshi, K., M. Bergé, M., S. K. Radhakrishnan, P.H. Viollier and P. Chien (2015). . Cell, 163(2):419-31. doi: 10.1016/j.cell.2015.09.030
Huitema, E., D. Matteson, S. Pritchard, S. Kumar Radhakrishnan and P.H. Viollier (2006) . Cell 124(5):1025-37
6 Nov 2020