Orateur
Description
The bacterial DNA segregation is mainly performed with the ParABS system. It is composed of ParB, a binding protein, ParA, an ATPase and parS, a specific binding DNA sequence that ParB binds parS with high affinity. Hundreds of ParB are recruited around parS into a complex, called ParBS, which displays liquid-like properties.
Recently, it has been shown that ParB is using energy stored as CTP in the cells according to the clamping and sliding model. Upon specific binding onto parS, ParB binds CTP that is used to switch the ParB into a clamp that is then released DNA to perform transient 1D diffusion until it detaches and unbinds CTP. The role of the CTP is not completely understood: neither the time scale of the ParBS formation nor the total number of ParB into ParBS could be accounted for with this model.
We hypothesize that the ParB clamping leads to an increase of the ParB-ParB interactions, leading to an increased speed and specificity of the ParBS formation during a liquid-like phase separation. This claim is supported by numerical simulations of ParB via a Lattice Gas combined with dedicated experiments of ParB mutants in CTP binding and hydrolysis.
