Figure 1

(A) Structural comparison of T4 RNA ligase 2 and archaeal RNA ligase PAB1020 active sites. Two structures were superimposed based on coordinates of pre-bound AMP and ATP homolog (AMPPNP) as well as known conserved amino acids of the ligase active sites. The T4Rnl2 structure is represented in grey and PAB1020 in yellow. The numbers of amino acids in the conserved motifs I-V (in parenthesis) are for T4Rnl2 and PAB1020 ortholog MthRnl, which were determined after sequence alignment of two archaeal enzymes. (B) The sequences of the conserved motifs I and V of MthRnl compared to corresponding motifs in the RNA and DNA ligases as discussed in the text. The listed RNA ligases are from: MthRnl (Methanobacterium thermoautotrophicum), PAB1020 (Pyrococcus abyssi), TS2126 (bacteriophage Thermus scotoductus), RM378 (bacteriophage Rhodothermus marinus), T4Rnl1 and T4Rnl2 (bacteriophage T4), AcNPV (Autographa californica nucleopolyhedrovirus). And DNA ligases are from: PBCV1 (Chlorella virus), MthDnl (Methanobacterium thermoautotrophicum), VacDnl (Vaccinia virus). The conserved lysines are shown in bold.