Substrate-binding model of the chlorophyll biosynthetic magnesium chelatase BchH subunit.
Photosynthetic organisms require chlorophyll and bacteriochlorophyll to harness light energy and transform water and carbon dioxide into carbohydrates and oxygen. The biosynthesis of these pigments is initiated by magnesium chelatase, an enzyme composed of BchI, BchD and BchH proteins, which catalyzes the insertion of Mg(2+) into protoporphyrin IX (Proto) to produce Mg-protoporphyrin IX. BchI and