A tubulin-like, filament forming GTPase; the motor component of the type III partition system presumably used to ensure correct segregation of this bacteriophage. In the presence of Mg(2+) and GTP (or GTP-gamma-S) assembles into filaments which upon polymerization are almost exclusively bound to GDP. Filament formation is cooperative, requiring a critical concentration. Formation occurs very quickly and is followed by disassembly as GTP is consumed. Unlike its plasmid homolog in B.thuringiensis (AC Q8KNP3) GTP-gamma-S does not alter filament formation (PubMed:22538818, PubMed:28230082). When forced to assemble with GDP instead of GTP it makes much stiffer, thicker filaments (PubMed:28230082). The filaments bind a DNA centromere-like site (tubC)-TubR complex which extends to surround the TubZ filaments (PubMed:22538818). 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 phage DNA within the cell (By similarity). GTP + H2O = GDP + H(+) + phosphate Monomer. In the presence of Mg(2+) and GTP assembles into 2-stranded filaments which coalesce into bundles. Binds a centromere-like site (tubC)-TubR complex. The TubZ-TubR-tubC complex bind to TubY which reshapes the filament bundles into rings (PubMed:22538818). A later paper by the same group shows 4-stranded filament formation and suggests the 2-stranded form is a short-lived intermediate (PubMed:28230082). 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 (PubMed:28230082). The C-terminus is thought to insert into the most distant monomer of the plus end of the filament, forming the complete active site and modulating filament assembly (Probable). This bacteriophage also exists as a circular plasmid prophage in its host. Belongs to the FtsZ family. TubZ subfamily.