Does a light-harvesting protochlorophyllide a/b-binding protein complex exist?
Recent in vitro studies have led to speculation that a novel light-harvesting protochlorophyllide a/b-binding protein complex (LHPP) might exist in dark-grown angiosperms. Structurally, it has been suggested that LHPP consists of a 5:1 ratio of dark-stable ternary complexes of the light-dependent NADPH: protochlorophyllide oxidoreductases A and B containing nonphotoactive protochlorophyllide b and photoactive protochlorophyllide a, respectively. Functionally, LHPP has been hypothesized to play major roles in establishing the photosynthetic apparatus, in protecting against photo-oxidative damage during greening, and in determining etioplast inner membrane architecture. However, the LHPP model is not compatible with other studies of the pigments and the pigment-protein complexes of dark-grown angiosperms. Protochlorophyllide b, which is postulated to be the major light-harvesting pigment of LHPP, has, for example, never been detected in etiolated seedlings. This raises the question: does LHPP exist?
Armstrong
G A
GA
Institute for Plant Sciences, Plant Genetics, Swiss Federal Institute of Technology (ETH), Universitätstr. 2, CH-8092 Zürich, Switzerland. gregory.armstrong@ipw.biol.ethz.ch
Apel
K
K
Rüdiger
W
W
D008027:Light; D010788:Photosynthesis; D063245:Plant Development; D010944:Plants / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism; D011485:Protein Binding; D011521:Protochlorophyllide / Q000378:metabolism*
D011521:Protochlorophyllide