TRANSCRIPTIONAL AND TRANSLATIONAL ANALYSIS OF FERREDOXIN AND FLAVODOXIN UNDER IRON AND NITROGEN STRESS IN ANABAENA SP STRAIN PCC-7120

In Anabaena sp. strain PCC 7120, vegetative cell ferredoxin synthesis under iron starvation was repressed 25-fold, whereas heterocyst ferred oxin synthesis decreased only 2.8-fold. Induction of flavodoxin under iron depletion was independent of the availability of combined nitroge n. Under iron stress but in the presence of combined nitrogen, fdxH an d nifH genes were transcriptionally active; although excision of the 1 1-kb element seemed to be completed, nitrogenase activity and the fdxH gene product were not detectable.