Transient change in the ATP pool of Anabaena cylindrica associated with ammonia assimilation

When N2-grown cells of Anabaena cylindrica were exposed to ammonia (50 micron to 5 mM) in the dark, the size of the ATP pool was reduced by 40% within 1 min, but restored after 5 or 6 min. The decrease in ATP was accompanied by increases in ADP and AMP, while the total adenylate content remained unaltered. The ammonia-induced change in the ATP pool was completely eliminated when algal cells were treated with L-methionine-DL-sulfoximine, an inhibitor of glutamine synthesis. These results suggest that ammonia is rapidly assimilated through the pathway mediated by glutamine synthetase accompanied by reduction of the ATP pool.