THE FUNGAL H-ATPASE FROM NEUROSPORA-CRASSA RECONSTITUTED WITH FUSICOCCIN RECEPTORS SENSES FUSICOCCIN SIGNAL()

Fusicoccin affects several physiological processes regulated by the pl asma membrane H+-ATPase in higher plants while other organisms having P-type H+-ATPases (e.g., fungi) are fusicoccin-insensitive, We have pr eviously shown that fusicoccin binding to its receptor is necessary fo r H+-ATPase stimulation and have achieved the functional reconstitutio n into liposomes of fusicoccin receptors and the H+-ATPase from maize, In this paper we show that fusicoccin sensitivity can be conferred on the H+-ATPase from Neurospora crassa, a fungus insensitive to fusicoc cin, In fact, H+ pumping by purified H+-ATPase from Neurospora crassa reconstituted into liposomes containing crude or partially purified fu sicoccin receptors from maize was markedly enhanced by fusicoccin. The stimulation of H+ pumping by fusicoccin is dependent upon pH, fusicoc cin, and protein concentration, as was reported for the system reconst ituted with both proteins from maize.