Synthesis of dinucleoside polyphosphates catalyzed by firefly luciferase and several ligases.

The findings presented here originally arose from the suggestion that the synthesis of dinucleoside polyphosphates (Np(n)N) may be a general process involving enzyme ligases catalyzing the transfer of a nucleotidyl moiety via nucleotidyl-containing intermediates, with release of pyrophosphate. Within this context, the characteristics of the following enzymes are presented. Firefly luciferase (EC 1.12. 13.7), an oxidoreductase with characteristics of a ligase, synthesizes a variety of (di)nucleoside polyphosphates with four or more inner phosphates. The discrepancy between the kinetics of light production and that of Np(n)N synthesis led to the finding that EL-AMP (L = dehydroluciferin), formed from the ELH(2)-AMP complex (LH(2) = luciferin) shortly after the onset of the reaction, was the main intermediate in the synthesis of (di)nucleoside polyphosphates. Acetyl-CoA synthetase (EC 6.2.1.1) and acyl-CoA synthetase (EC 6.2.1. 8) are ligases that synthesize p(4)A from ATP and P(3) and, to a lesser extent, Np(n)N. T4 DNA ligase (EC 6.5.1.1) and T4 RNA ligase (EC 6.5.1.3) catalyze the synthesis of Np(n)N through the formation of an E-AMP complex with liberation of pyrophosphate. DNA is an inhibitor of the synthesis of Np(n)N and conversely, P(3) or nucleoside triphosphates inhibit the ligation of a single-strand break in duplex DNA catalyzed by T4 DNA ligase, which could have therapeutic implications. The synthesis of Np(n)N catalyzed by T4 RNA ligase is inhibited by nucleoside 3'(2'),5'-bisphosphates. Reverse transcriptase (EC 2.7.7.49), although not a ligase, catalyzes, as reported by others, the synthesis of Np(n)ddN in the process of removing a chain termination residue at the 3'-OH end of a growing DNA chain.