In Anabaena sp. PCC 7120, FurA is a global transcriptional regulator whose expression is strongly
induced by NtcA in proheterocysts and remains stably expressed in mature heterocysts. In the present
study, overexpression of furA partially suppressed heterocyst differentiation by impairing morphogenesis
at an early stage. Recombinant purified FurA specifically bound in vitro to the promoter
regions of ntcA, while quantitative RT-PCR analyses indicated that furA overexpression strongly
affected the transient increase of ntcA expression that occurs shortly after nitrogen step-down.
Overall, the results suggest a connection between iron homeostasis and heterocyst differentiation
via FurA, by modulating the expression of ntcA