The complete purification and characterization of three forms of ferredoxin-NADP(+) oxidoreductase from a thermophilic cyanobacterium Synechococcus elongatus.
The petH gene, encoding ferredoxin-NADP(+) oxidoreductase (FNR), was isolated from a thermophilic cyanobacterium, Synechococcus elongatus (the same strain as Thermosynechococcus elongatus). The petH gene of S. elongatus was a single copy gene, and the N-terminal region of PetH showed a sequence similarity to the CpcD-phycobilisome linker polypeptide. The amino acid sequence of the catalytic domains of PetH was markedly similar to those from mesophilic cyanobacterial PetH and higher plant FNR. The enzymatically active FNR protein was purified to homogeneity from S. elongatus as three forms corresponding to the 45-kDa form retaining the CpcD-like domain, the 34-kDa form lacking the CpcD-like domain, and the 78-kDa complex with phycocyanin. The FNR in the 78-kDa complex was tolerant to proteolytic cleavage. However, the dissociation of phycocyanin from the 78-kDa complex induced to specific proteolysis between the CpcD-like domain and the FAD-binding domain to give rise to the 34-kDa form of FNR. The enzymatic activity of the 45-kDa form was thermotolerant, but the 45-kDa form readily aggregated under the storage at -30 degrees C. These results suggest that the association with phycocyanin via CpcD-like domain gives remarkable stability to S. elongatus FNR.
Nakajima
Masato
M
Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, 920-1192 Japan.
Sakamoto
Toshio
T
Wada
Keishiro
K
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics; D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005420:Flavoproteins; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D045524:Phycobilisomes; D010798:Phycocyanin / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D001426:Bacterial Proteins; D002352:Carrier Proteins; D005420:Flavoproteins; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins; D045524:Phycobilisomes; C082501:cpcD phycobilisome linker protein, cyanobacteria; D010798:Phycocyanin; D005287:Ferredoxin-NADP Reductase; C082502:petH protein, Bacteria