InterPro: IPR005970 Light-independent protochlorophyllide reductase, N subunit

Synonym: dark protochlorophyllide reductase

Protochlorophyllide reductase catalyzes the reductive formation of chlorophyllide from protochlorophyllide during biosynthesis of chlorophylls and bacteriochlorophylls. The light-independent (dark) form of protochlorophyllide reductase plays a key role in the ability of gymnosperms, algae, and photosynthetic bacteria to form chlorophyll in the dark. Genetic and sequence analyses have indicated that dark protochlorophyllide reductase consists of three protein subunits that exhibit significant sequence similarity to the three subunits of nitrogenase, which catalyzes the reductive formation of ammonia from dinitrogen. Dark protochlorophyllide reductase activity was shown to be dependent on the presence of all three subunits, ATP, and the reductant dithionite.

This enzyme describes the N subunit of the dark form protochlorophyllide reductase, a nitrogenase-like enzyme [1].