Session: Session 4

The phosphoproteome signature of Listeria monocytogenes dormancy

When exposed to stressful conditions, some bacteria can transition to a viable but non-culturable (VBNC) state. VBNC bacteria have lost their ability to grow on standard culture media, despite remaining viable and with a relatively active metabolism. By hibernating into a VBNC state, bacteria become more protected against environmental stresses, thus maximizing their chances of survival. The VBNC state is particularly problematic in the case of pathogens, as standard methods used for bacterial identification and enumeration are reliant on growth, and thus unsuitable for VBNC cells. Moreover, as the VBNC state is potentially reversible (resurrection), pathogenic bacteria may recover their virulence potential. Although hundreds of bacterial species have been reported to transition into the VBNC state, the underlying molecular mechanisms remain elusive. We have recently addressed this question by characterizing the VBNC state in the environmentally ubiquitous Gram-positive pathogen Listeria monocytogenes (Lm). By combining fluorescence microscopy and cryo-electron tomography with genetic and biochemical approaches, we discovered that starvation in mineral water drives Lm into a VBNC state via a unique mechanism of cell wall shedding that generates osmotically stable cell wall-deficient coccoid forms. Here, we aim to investigate the regulatory role of protein post-translational modifications, in particular phosphorylation on tyrosine, serine and threonine residues, in VBNC state transition. Phosphoproteome will be recovered via enrichment method and then analyzed by LC-MS/MS. Identification and statistical analysis will be performed by using i2MassChroQ and R scripts, respectively. By profiling the phosphoproteome dynamics of Lm transitioning into a VBNC state, we anticipate that our results will provide novel insights on bacterial dormancy and could lead to the identification of molecular targets to be used in the fight against drug-tolerant dormant bacteria