Zinc phosphodiesterase, which displays some tRNA 3'-processing endonuclease activity. Probably involved in tRNA maturation, by removing a 3'-trailer from precursor tRNA. Can also catalyze the 5' end cleavage of the 5S rRNA. Endonucleolytic cleavage of RNA, removing extra 3' nucleotides from tRNA precursor, generating 3' termini of tRNAs. A 3'-hydroxy group is left at the tRNA terminus and a 5'-phosphoryl group is left at the trailer molecule. Binds 2 Zn(2+) ions. Inhibited by high salt concentrations. Optimum pH is 5.5. Optimum temperature is 37 degrees Celsius. Homodimer. Belongs to the RNase Z family.