A tubulin-like GTPase that forms filaments, which are required for positioning viral DNA and capsids in the middle of the host cell for optimal replication (PubMed:28082593, PubMed:22726436, PubMed:25429514, PubMed:31199917, PubMed:28813669). The motor component of a partition system which pushes phage DNA (encased by protein gp105) to the center of the bacterial host cell (PubMed:28082593, PubMed:28813669). Also required for movement of phage capsids to the vicinity of the viral DNA and rotation of the encased viral DNA at midcell (PubMed:31199917). Forms filaments during the lytic phase, which position phage DNA at the center of the bacterial host cell (PubMed:22726436, PubMed:25429514, PubMed:31199917, PubMed:28082593, PubMed:28813669). Filaments have a three-stranded intertwined achitecture and form a spindle-like cytoskeleton within the infected cell (PubMed:24631461). Has GTPase activity (PubMed:22726436). Filaments grow at the plus end and depolymerize at the minus end, a process called treadmilling, and switch from growing in a polar manner to catastrophic depolymerization, i.e. they display dynamic instability, like tubulin. In infected host cells the filament ends close to the cell pole are relatively stable, while the other end near the phage DNA is highly dynamic (PubMed:25429514). Both capsid movement and DNA rotation probably require treadmilling (Probable). GTP + H2O = GDP + H(+) + phosphate The non-hydrolyzable GTP analog GMPCPP stabilizes filaments, which never disassemble. Homomultimer (PubMed:22726436, PubMed:25429514). Polymerizes in a strictly GTP-dependent manner (PubMed:22726436, PubMed:25429514). In infected host cells forms a spindle-like structure emanating from each cell pole. Expressed by 1 hour post-infection (at protein level). Consists of two domains: a nucleotide-binding N-terminus that hydrolyzes GTP and a C-terminus domain necessary for polymerization (PubMed:22726436). The domains are bridged by a long, central helix (PubMed:22726436). Interactions between the C-terminus and the following monomer drive polymerization (PubMed:22726436). Belongs to the FtsZ family. PhuZ subfamily.