Adds poly(A) tail to the 3' end of many RNAs, which usually targets these RNAs for decay. Plays a significant role in the global control of gene expression, through influencing the rate of transcript degradation, and in the general RNA quality control. Rho-independent transcription terminators may serve as polyadenylation signals. Seems to be involved in plasmid copy number control. ATP + RNA(n) = diphosphate + RNA(n)-3'-adenine ribonucleotide Monomer. Interacts with CsdA, RhlE and SrmB. Transcription regulation of pcnB is a complex process that involves several factors such as Sigma-70 (rpoD), Sigma-S (rpoS), ppGpp and DksA. Uses the non-canonical initiation codon AUU, which limits pcnB expression. Belongs to the tRNA nucleotidyltransferase/poly(A) polymerase family. Truncated N-terminus. Extended N-terminus.