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 160 residues (CT domain) acts as a general tRNA nuclease, and inhibits growth in E.coli upon overexpression. Cleaves specifically within the T-loop of E.coli tRNA2(Arg) (between the post-transcriptionally modified thymidine-T55 and pseudouridine-Y56); also degrades most other tRNAs (PubMed:22435733). Cleaves unmodified tRNA(Gln) and tRNA(Asp), showing the universal post-translational tRNA modifications present in the T-loop are not required for CT activity (PubMed:27445337). Inactive CT domain binds tRNA, probably in a complex with 4 CT domains and 4 tRNAs (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:27445337). 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 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. Specifically interacts with cognate immunity protein CdiI, which blocks its tRNA nuclease activity (PubMed:22435733, PubMed:27445337). The CT domain forms a tetramer both with and without tRNA; each subunit binds tRNA in its presence (PubMed:27445337). Secreted to the cell surface by CdiB, its two partner secretion pathway (TPS) partner. The C-terminal domain (CT) has toxic activity, which can be exchanged between N-terminal sections from different toxin molecules. Belongs to the CdiA toxin family.