6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m RNA editing, posttranscriptional RNA processing in which uridylate residues are inserted into and deleted from pre-mRNAs to create start and stop codons, also acts to reseal mRNAs cleaved at incorrect sites 6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m RNA editing, unique U insertion and U deletion process, involves cycles of pre-mRNA cleavage, terminal U addition or U removal, and religation, band IV is the RNA editing ligase needed to seal in U deletion 6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m RNA-editing 6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m the enzyme is essential for survival of both insect and bloodstream forms of the parasite 6.5.1.3 additional information the group I intron from cyanobacterium Anabaena sp. catalyzes phosphodiester bond formation using a triphosphate on the 5'-terminal nucleotide, much like protein polymerases and engineered ribozymes. In the process, this ribozyme forms a unique circular RNA that incorporates the exogenous guanosine cofactor added during self-splicing 6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m the L1 ligase is regioselective for formation of the biologically relevant 5' to 3' phosphodiester bond rather than a 5' to 2' bond 6.5.1.3 ATP + (ribonucleotide)n + (ribonucleotide)m Trl1 executes the end-healing and end-sealing steps of tRNA splicing, requires a 2'-PO4 end for tRNA splicing in vivo