Endonuclease that can use RNA and single-stranded DNA as substrates (PubMed:23620482). In contradiction with PubMed:23620482, cannot hydrolyze single-stranded DNA and does not cleave mismatches (PubMed:17651368). Endonucleolytic cleavage to 5'-phosphomononucleotide and 5'-phosphooligonucleotide end-products. Binds 3 divalent metal cations (PubMed:23620482). Can use Mn(2+) with a lower efficiency than Zn(2+) ions (PubMed:23620482). Optimum pH is 5.5 with RNA and ssDNA as substrates. Monomer. Belongs to the nuclease type I family.