Toxic component of a type IV toxin-antitoxin (TA) system (PubMed:14594833, PubMed:21166897, PubMed:22515815, PubMed:28931012, PubMed:28257056). Acts as a dual toxin inhibitor that blocks cell division and cell elongation in genetically separable interactions with FtsZ and MreB (PubMed:28931012). Interacts with cytoskeletal proteins FtsZ and MreB; inhibits FtsZ GTP-dependent polymerization and GTPase activity as well as MreB ATP-dependent polymerization (PubMed:21166897, PubMed:28931012). Binds to both the N- and C-terminus of FtsZ, likely blocking its polymerization and localization, leading to blockage of cell division (PubMed:21166897, PubMed:28931012). Overexpression results in inhibition of growth in liquid cultures and decrease in colony formation; these effects are overcome by concomitant expression of antitoxin CbeA (YeeU) (PubMed:14594833). In other experiments cells swell, by 6 hours are lemon-shaped and by 24 hours those that have not lysed are spherical with diminished polar regions (PubMed:21166897, PubMed:28931012). Toxic effects are neutralized by cognate antitoxin CbeA, although there is no direct interaction between the 2 proteins (PubMed:14594833, PubMed:22515815). Toxic effects are also neutralized by overexpression of noncogate antitoxins YafW and YpjF (PubMed:28257056). Interacts with FtsZ (PubMed:21166897, PubMed:22515815, PubMed:28931012). Interacts with MreB (PubMed:21166897, PubMed:28931012). Expressed in mid-log phase at lower levels than toxin relE. The N-terminal 15 residues are required for interaction with both FtsZ and MreB, while the C-terminal 63 residues are required for interaction with MreB. No visible phenotype (PubMed:21166897). Deletion of 3 type IV toxin genes (cbtA, ykfI, ypfJ) leads to a slight reduction in resistance to oxidative stress, has no effect on cell growth (PubMed:28257056). Encoded in prophage CP4-44. Belongs to the CbtA/YkfI/YpjF toxin family.