Catalyzes the addition and repair of the essential 3'-terminal CCA sequence in tRNAs without using a nucleic acid template. Adds these three nucleotides in the order of C, C, and A to the tRNA nucleotide-73, using CTP and ATP as substrates and producing inorganic pyrophosphate. Also shows highest phosphatase activity in the presence of Ni(2+) and hydrolyzes pyrophosphate, canonical 5'-nucleoside tri- and diphosphates, NADP, and 2'-AMP with the production of Pi. Displays a metal-independent phosphodiesterase activity toward 2',3'-cAMP, 2',3'-cGMP, and 2',3'-cCMP. Without metal or in the presence of Mg(2+), this protein hydrolyzes 2',3'-cyclic substrates with the formation of 2'-nucleotides, whereas in the presence of Ni(2+), it also produces some 3'-nucleotides. These phosphohydrolase activities are probably involved in the repair of the tRNA 3'-CCA terminus degraded by intracellular RNases. a tRNA precursor + ATP + 2 CTP = a tRNA with a 3' CCA end + 3 diphosphate Magnesium is required for nucleotidyltransferase activity. Nickel for phosphatase activity. Both phosphatase and phosphodiesterase activities are competitively inhibited by low concentrations of the E.coli tRNA (10 nM). Cu(2+) stimulates the hydrolysis of pyrophosphate and ATP and completely inhibits the hydrolysis of 2'-AMP. The phosphodiesterase activity is inhibited by Zn(2+), Cu(2+) and Co(2+). Optimum pH is 9.4 for AMP incorporation, 10.0 for CMP incorporation, and 7.0 for the phosphatase and phosphodiesterase activities. Monomer. Can also form homodimers and oligomers, but with low levels. Comprises two domains: an N-terminal domain containing the nucleotidyltransferase activity and a C-terminal HD domain associated with both phosphodiesterase and phosphatase activities. A single active site specifically recognizes both ATP and CTP and is responsible for their addition. Belongs to the tRNA nucleotidyltransferase/poly(A) polymerase family. Bacterial CCA-adding enzyme type 1 subfamily.