A novel endoribonuclease from the marine sponge Tethya aurantium specific to 2′,5′-phosphodiester bonds

► We detected a novel 2-5A degrading enzymatic activity in a marine sponge. ► The enzyme is a metal-independent endonuclease generating 2′,3′-cyclic phosphates. ► Oligoadenylates with 3′-5′ linkages are not substrates for the enzyme. ► The preferred substrates for the enzyme are 5′-phosphorylated 2′,5′-oligoadenylates. ► The enzyme is able to catalyze the degradation of 2′,5′-linked heteronucleotides.