A tubulin-like, filament forming GTPase; the motor component of the type III plasmid partition system which ensures correct segregation of the pXO1 plasmid. Essential for plasmid replication (PubMed:16585744). 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). Has a high GTPase activity; in the presence of GTP assembles into dynamic filaments which bind almost exclusively GDP. Filament formation is cooperative, requiring a critical concentration. Formation occurs very quickly and is followed by disassembly as GTP is consumed. Small amounts of GTP-gamma-S stabilize filaments (PubMed:18198178, PubMed:18179418). Has high GTP and dGTPase activity, 6-fold lower ATPase activity. Forms filaments in the presence of ATP that also disassemble. Weakly binds DNA in a GTP-dependent, non-sequence-specific manner; GTP hydrolysis is not required for DNA-binding (PubMed:18179418). GTP + H2O = GDP + H(+) + phosphate GTPase inhibited by GTP-gamma-S, which also stabilizes filaments. Polymerizes to form two-stranded filaments and bundles at higher concentration in the presence of GTP (PubMed:18198178, PubMed:18179418). Binds to the TubR-tubC protein DNA complex (By similarity). 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). Loss of plasmid replication. Belongs to the FtsZ family. TubZ subfamily.