A DNA-binding protein that is part of the type III plasmid partition system used to ensure correct segregation of the pBtoxis plasmid. Cooperatively binds to the centromere-like site (tubC), which may seed filament formation by the TubZ polymerizing GTPase, stabilizing TubZ filaments. TubR-tubC complexes track the depolymerizing minus end of the filament, probably pulling plasmid within the cell (PubMed:20534443, PubMed:23010931, PubMed:25825718). Required for plasmid replication (PubMed:16936050, PubMed:17873046). Negatively regulates levels of TubZ; its effect on RNA expression has not been shown (Probable). Specifically binds iterons, 12-bp imperfect direct repeats that function as a plasmid origin of replication (PubMed:17873046, PubMed:23010931, PubMed:25825718). Four TubR dimers bind to tubC, forming an extended bent DNA-protein filament with protein wrapping helically around the outside of the DNA (PubMed:20534443, PubMed:23010931). Homodimer (PubMed:20534443, PubMed:23010931). Binds to tubC DNA, the TubR-DNA complex binds to TubZ (PubMed:17873046, PubMed:20534443). Probably part of the tubR-tubZ operon. Although this has the same function as TubR of B.cereus strain ATCC 10987 there is little sequence homology and the dimerization interface is different. Loss of plasmid replication (PubMed:16936050, PubMed:17873046). TubZ levels increase, TubZ still polymerizes (PubMed:17510284). A miniplasmid containing this and downstream gene tubZ is able to replicate in B.thuringiensis subsp. israelensis and express insect toxin proteins. The miniplasmid could be used to make plasmids for insect toxin overexpression. The pBtoxis plasmid encodes all the major endotoxin proteins (Cyt1Aa, Cry4Aa, Cry4Ba, and Cry11Aa) responsible for the mosquito larvicidal activity of strain 4Q2.