Assembly of NADPH: protochlorophyllide oxidoreductase complex is needed for effective greening of barley seedlings.
NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR) is the key enzyme in the light-induced greening of higher plants. A unique light-harvesting POR:Pchlide complexes (LHPP) has been found in barley etioplasts, but not in other plant species. Why PORs from barley, but not from other plants, can form LHPP? And its function is not well understood. We modeled the barley and Arabidopsis POR proteins and compared molecular surface. The results confirm the idea that barley PORA can form a five-unit oligomer that interacts with a single PORB. Chemical treatment experiments indicated that POR complex may be formed by dithiol oxidation of cysteines of two adjacent proteins. We further showed that LHPP assembly was needed for barley POR functions and seedling greening. On the contrary, Arabidopsis POR proteins only formed dimers, which were not related to the functions or the greening. Finally, POR complex assembly (including LHPP and POR dimers) did not affect the formation of prolamellar bodies (PLBs) that function for efficient capture of light energy for photo conversion in etioplasts.
College of Biology and Science, Sichuan Agricultural University, Ya'an 625014, China.
Ming
M
Yuan
Da-Wei
DW
Zhang
Zhong-Wei
ZW
Zhang
Yang-Er
YE
Chen
Shu
S
Yuan
Yi-Ran
YR
Guo
Hong-Hui
HH
Lin
D029681:Arabidopsis Proteins / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D001467:Hordeum / Q000201:enzymology*; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010788:Photosynthesis; D011521:Protochlorophyllide / Q000378:metabolism*; D036226:Seedlings / Q000201:enzymology*
D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; D002734:Chlorophyll; D011521:Protochlorophyllide; D009249:NADP; D010088:Oxidoreductases