Probable bifunctional enzyme which has pAp-phosphatase and may have oligoribonuclease activities. Converts 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP. Complementation studies suggest it also has RNA oligoribonuclease activity, although this has not been shown in vitro using 5- or 20-mers. Involved in superoxide stress response and sulfur assimilation. adenosine 3',5'-bisphosphate + H2O = AMP + phosphate Increased sensitivity to superoxide stress inducers methyl viologen and menadione. Grows poorly in the absence of cysteine. Part of the SMU_1296-SMU_1298 (rpmE2) operon. Is able to complement a cysQ mutant in E.coli. Belongs to the NrnA oligoribonuclease family.