Photosynthetic Genes and Their Expression

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A low-molecular-mass subunit of photosystem II complex was purified and its partial amino acid seguence was determined. It was found that its gene is encoded by the choloroplast genome, and the gene was termed as psnK. Precursors of the extrinsic photosystem II proteins, 33-kDa and 23-kDa proteins were synthesized from their cDNAs by in vitro transcription and translation system, and their first precessing sited were determined with the stromal processing enzyme activity. The gene for the extrinsic 33-kDa protein of a cyanobacterium was expressed in E. coli, and the processing site of this protein after the expression in E. coli was determined.2. Action spectra for the light-induced transcription of the Rubisco small subunit and large subunit genes (rbcS and rbcL) were measured. the result suggests that the transcription of rbcS is induced by phytochrome Pfr and that the transcription of rbcL is induced also by phytochrome Pfr, but in addition, by a blue light-absorbing pigment. It was disclosed that methylation of plastid DNA regulates the transcription of rbcL in the non-photosynthetic cells of higher plants. A new Rubisco gene was cloned from a photosynthetic bacterium Chromatium vinosum, and it was found that this gene, but not the previously cloned gene, is expressed in the bacterium.3. The cDNA and genomic DNA for maize PEP carboxylase were cloned and their nucleotide sequences were determined. The cDNA for aspartate aminoacyltransferase from Panicum maximam was cloned and its nucleotide sequence was determined.4. The cDNA for a 15.5 kDa subunit of tobacco photosystem I complex was cloned and its nucleotide sequence was determined.