主催: The Japanese Society of Plant Physiologists
p. 60
Nitrite reductase (NiR), an enzyme containing a single siroheme and an [4Fe-4S] cluster, catalyzes the six-electron reduction of nitrite to ammonia in cyanobacteria and higher plants. Ferredoxin is the typical electron donor for NiR, and donates six electrons by an intermolecular transfer to the [4Fe-4S] cluster through the siroheme active-site. Plectonema boryanum NiR (FL-NiR) contains a redox-active ferredoxin-domain at the C-terminal region of its polypeptide. FL-NiR is homologous to many known assimilatory nitrite reductases. The P. boryanum NiR gene has been cloned from the genomic DNA, and over-expressed in Escherichia coli. A truncated FL-NiR containing only the NiR domain, or only the ferredoxin domain, and an authentic Synechocystis sp. 6803 NiR were also expressed. Physiological and enzymatic properties of these authentic NiRs and the truncated versions will be presented.
