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. Has no poly(A) polymerase activity. a tRNA precursor + ATP + 2 CTP = a tRNA with a 3' CCA end + 3 diphosphate Homodimer. 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 3 subfamily. Was originally predicted to have poly(A) polymerase activity (EC 2.7.7.19), and its gene was named papS.