Down-regulation of the PSI-F subunit of photosystem I (PSI) in Arabidopsis thaliana. The PSI-F subunit is essential for photoautotrophic growth and contributes to antenna function.
The PSI-F subunit of photosystem I is a transmembrane protein with a large lumenal domain. The role of PSI-F was investigated in Arabidopsis plants transformed with an antisense construct of the psaF cDNA. Several plant lines with reduced amounts of the PSI-F subunit were generated. Many of the transgenic plants died, apparently because they were unable to survive without the PSI-F subunit. Plants with 5% of PSI-F were capable of photoautotrophic growth but were much smaller than wild-type plants. The plants suffered severely under normal growth conditions but recovered somewhat in the dark indicating chronic photoinhibition. Photosystem I lacking PSI-F was less stable, and the stromal subunits PSI-C, PSI-D, and PSI-E were present in lower amounts than in wild type. The lack of PSI-F resulted in an inability of light-harvesting complex I-730 to transfer energy to the P700 reaction center. In thylakoids deficient in PSI-F, the steady state NADP(+) reduction rate was only 10% of the wild-type levels indicating a lower efficiency in oxidation of plastocyanin. Surprisingly, the lack of PSI-F also gave rise to disorganization of the thylakoids. The strict arrangement in grana and stroma lamellae was lost, and instead a network of elongated and distorted grana was observed.
Haldrup
A
A
Plant Biochemistry Laboratory, Department of Plant Biology, the Royal Veterinary and Agricultural University, 40 Thorvaldsensvej, DK-1871 Frederiksberg C, Denmark.
Simpson
D J
DJ
Scheller
H V
HV
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D005822:Genetic Vectors; D015151:Immunoblotting; D008027:Light; D008854:Microscopy, Electron; D009249:NADP / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010641:Phenotype; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics* / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D013050:Spectrometry, Fluorescence; D013696:Temperature; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors
D018076:DNA, Complementary; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D009249:NADP; D010100:Oxygen