Prediction of an ATP reactive center in the small subunit, gpNu1, of the phage lambda terminase enzyme.

The small subunit of the bacteriophage lambda terminase enzyme, the product of the phage's Nu1 gene, is shown to contain amino acid segments homologous to those present in a large number of ATPases. In keeping with these predictions, the purified protein has been found to hydrolyze ATP with a relatively low turnover number. Terminase holoenzyme is a known ATPase, and the biochemical significance of an ATP-interactive center situated in the gpNu1 subunit is discussed.