PARENT SESSION
Posters P6C Photosynthesis, respiration and alternative electron sinks. Abstracts (660-680)

Functional studies on A. thaliana ferredoxins. Guy Hanke^*,1, Yoshinori Satomi¹, Toshifumi Takao¹, Toshiharu Hase¹, ¹ Institute For Protein Research, Suita, Osaka, Japan

ABSTRACT- Ferredoxins (Fds) are the unique soluble electron transport proteins in higher plant chloroplasts and therefore support diverse bioassiimilatory and biosynthetic processes by distributing electrons to various enzymes. During photosynthesis the enzyme Fd:NADP(H) oxidoreductase (FNR) catalyzes Fd dependent reduction of NADP⁺ (for use in carbon fixation), and in non-photosynthetic conditions mediates the reverse reaction to reduce Fd (for the bioassimilation of other inorganic nutrients). These two proteins therefore represent electron transfer partners at a critical branch point in chloroplast redox metabolism. Completion of the A. thaliana genome revealed surprising variety in both Fd and FNR proteins. Recombinant expression of the different Fd isoforms has revealed differences in their physical properties. In an attempt to assign specific function to these different isoproteins we have examined their expression patterns under different nutrient growth regimes by semi-quantiative RT-PCR, and used a combination of Fd-column chromatography, MALDI-TOF mass spectrometry and protein sequencing to identify proteins which interact with Fd.

KEY WORDS: arabidopsis, ferredoxin, recombinant expression, mass spectrometry