3'-5' exoribonuclease that releases 5'-nucleoside monophosphates and is involved in maturation of structured RNAs (By similarity). Required for the expression of virulence genes on the large plasmid of S.flexneri at the post-transcriptional level. Exonucleolytic cleavage in the 3'- to 5'-direction to yield nucleoside 5'-phosphates. Monomer. Belongs to the RNR ribonuclease family. RNase R subfamily. Extended N-terminus. Extended N-terminus. Several sequencing errors.