6.5.1.3 additional information the enzyme seals nicked 3'-OH/5'-PO4 duplexes in which the 3'-OH strand is RNA. The enzyme entails reaction with ATP to form a covalent enzyme-AMP intermediate, transfer of AMP to the nick 5'-PO4, and attack of the RNA 3'-OH on the adenylylated nick to form a 3'-5' phosphodiester Naegleria gruberi ? - ? 89