Toxic component of a toxin-immunity protein module, which functions as a cellular contact-dependent growth inhibition (CDI) system. CDI modules allow bacteria to communicate with and inhibit the growth of closely related neighboring bacteria in a contact-dependent fashion. The C-terminal 301 residues (the CT fragment) cleaves near the C-terminus of E.coli tRNA1B(Ala), probably preventing tRNA charging, and inhibits growth in E.coli. A truncated CT fragment (residues 2948-3122) has tRNA endonuclease activity on several B.thailandensis tRNAs as well as tRNA2(Arg) where it cleaves after A-70 and U-71 (PubMed:22435733, PubMed:25174572). Inactive CT domain binds tRNA, probably in a 1:1 complex (PubMed:27445337). Toxic activity is neutralized by coexpression of the cognate immunity protein CdiI in E.coli, but not by non-cognate immunity proteins from other strains of B.pseudomallei (PubMed:22435733, PubMed:23236156). May use lipopolysaccharide as its target cell receptor (PubMed:25786241). Probably gains access to the cytoplasm of target cells (B.thailandensis strain E264) by using integral inner membrane protein BTH_II0599 (PubMed:25786241, PubMed:26305955). Protein BTH_I0359 is also implicated in an unknown fashion in CDI in B.thailandensis strain E264 (PubMed:25786241). Expression of this cdiAIB locus in B.thailandensis confers protection against other bacteria carrying the locus; growth inhibition requires cellular contact. The CdiA protein is thought to be exported from the cell through the central lumen of CdiB, the other half of its two-partner system (TPS). The TPS domain probably remains associated with CdiB while the FHA-1 domain forms an extended filament with the receptor-binding domain (RBD) at its extremity; in the secretion arrested state the C-terminus of the RBD domain form a hairpin-like structure as the FHA-2, PT and CT domains are periplasmic. Upon binding to a target cell outer membrane receptor (possibly a lipoprotein in this CDI) a signal is transmitted to activate secretion. The filament elongates slightly, the rest of CdiA is secreted and the FHA-2 domain becomes stably associated with the target cell's outer membrane where it facilitates entry of the toxic CT domain into the target cell periplasm. From there the toxic CT domain is cleaved and gains access to the target cell cytoplasm via an inner membrane protein (probably inner membrane protein BTH_II0599). Interacts with cognate immunity protein CdiI, which blocks its tRNA nuclease activity (Probable). The truncated CT fragment (residues 2948-3122) specifically interacts with cognate CdiI which inhibits the tRNA nuclease activity. The truncated CT is more stable in vitro than the original CT fragment characterized in E.coli. Secreted to the cell surface by CdiB, its two partner secretion pathway (TPS) partner (Probable). Probably translocated into the target cell cytoplasm as intracellular CdiI inhibits tRNase activity. Toxin translocation into the target cell depends on the proton motive force (pmf) of the target cell, but not on tolA or tonB. The pmf is probably required for translocation across the target cell inner membrane from its periplasm. The C-terminal domain (CT) has toxic activity, which can be exchanged between N-terminal sections from different toxin molecules (PubMed:22435733, PubMed:25174572). A subdomain of the CT has tRNase activity and can be targeted to usually non-susceptible bacteria by cloning. Exchanging this toxic domain between CdiA proteins alters the inner membrane protein delivery system but not the CdiI immunity protein, strongly suggesting CdiI recognizes only the toxic domain (PubMed:26305955). In the N-terminal section; belongs to the CdiA toxin family.