A tubulin-like, filament forming GTPase; the motor component of the type III plasmid partition system which ensures correct segregation of the pBCXO1 plasmid. It is essential for plasmid replication (By similarity). Binds GTP and forms filaments. The filaments seed from a DNA centromere-like site (tubC)-TubR complex which extends to surround the TubZ filaments. Highly dynamic filaments grow at the plus end and depolymerize at the minus end, a process called treadmilling. TubR-tubC complexes track the depolymerizing minus end of the filament, probably pulling plasmid within the cell (By similarity). GTP + H2O = GDP + H(+) + phosphate Forms filaments. Binds to the TubR-tubC protein DNA complex. Forms long, dynamic filaments. Consists of two domains: a nucleotide-binding N-terminus that hydrolyzes GTP and a C-terminus domain necessary for polymerization. The domains are bridged by a long, central helix (By similarity). Interactions between the C-terminus and the following monomer drive polymerization (By similarity). Belongs to the FtsZ family. TubZ subfamily.