Distinct forms of ferredoxin - NADP+ reductase are expressed in photosynthetic and nonphotosynthetic plant tissues. Both enzymes catalyze electron transfer between NADP(H) and ferredoxin; whereas in leaves the enzyme transfers reducing equivalents from photoreduced ferredoxin to NADP+ in photosynthesis, in roots it has the opposite physiological role, reducing ferredoxin at the expense of NADPH mainly for use in nitrate assimilation. Here, structural and kinetic properties of a nonphotosynthetic isoform were analyzed to define characteristics that may be related to tissue-specific function. Compared with spinach leaf ferredoxin - NADP+ reductase, the recombinant corn root isoform showed a slightly altered absorption spectrum, a higher pI, a >30-fold higher affinity for NADP+, greater susceptibility to limited proteolysis, and an ∼20 mV more positive redox potential. The 1.7 Å resolution crystal structure is very similar to the structures of ferredoxin - NADP+ reductases from photosynthetic tissues. Four distinct structural features of this root ferredoxin - NADP+ reductases are an alternate conformation of the bound FAD molecule, an alternate path for the amino-terminal extension, a disulfide bond in the FAD-binding domain, and changes in the surface that binds ferredoxin.
|Titolo:||Biochemical and crystallographyc characterization of ferredoxin-NADP+ reductase from nonphotosynthetic tissues|
ALIVERTI, ALESSANDRO (Primo)
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
|Data di pubblicazione:||2001|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/bi011224c|
|Appare nelle tipologie:||01 - Articolo su periodico|