This system is also used by most bacteria for chromosome segregation. 
Type I partition systems are composed of an ATPase which contains Walker motifs and a CBP which is structurally distinct in type Ia and Ib. ATPases and CBP from type Ia are longer than the ones from type Ib, but both CBPs contain an arginine finger in their N-terminal part.
ParA proteins from different plasmids and bacterial species show 25 to 30% of sequence identity to the protein ParA of the plasmid P1.
The partition of type I system uses a "diffusion-ratchet" mechanism. This mechanism works as follows:
# Dimers of ParA-ATP dynamically bind to nucleoid DNA 
# ParA in its ATP-bound state interacts with ParB bound to parS 
# ParB bound to parS stimulates the release of ParA from the nucleoid region surrounding the plasmid
# The plasmid then chases the resulting ParA gradient on the perimeter of the ParA depleted region of the nucleoid
# The ParA that was released from the nucleoid behind the plasmid's movement redistributes to other regions of the nucleoid after a delay 
# After plasmid replication, the sister copies segregate to opposite cell halves as they chase ParA on the nucleoid in opposite directions
There are likely to be differences in the details of type I mechanisms.
Type 1 partition has been mathematically modelled with variations in the mechanism described above.