Photosynthetic Genes and Their Expression

纯化了光系统II复合体的一个低分子质量亚基，并测定了其部分氨基酸序列。发现其基因由胆绿体基因组编码，命名为pSnK。外源光系统II蛋白的前体33-kDa和23-kDa蛋白通过体外转录和翻译系统合成，并用基质加工酶活性确定它们的第一处理位点。目的：1.将蓝藻外源33-kDa蛋白基因在大肠杆菌中表达，并确定该蛋白在大肠杆菌中表达后的加工位点。测定了Rubisco小亚基和大亚基基因(rbcs和rbcL)在光诱导下转录的作用光谱。结果表明，RBC的转录受光敏色素PFR的诱导，rbcL的转录也受光敏色素PFR的诱导，但还受一种蓝光吸收色素的诱导。在高等植物的非光合作用细胞中，叶绿体DNA的甲基化调控着rbcL的转录。从一株光合作用细菌Chromatum vinosum中克隆了一个新的Rubisco基因，并发现该基因在该细菌中表达，而不是先前克隆的基因。克隆了玉米PEP羧基酶的cDNA和基因组DNA，并测定了它们的核苷酸序列。克隆了天冬氨酸氨基转移酶基因，并测定了其核苷酸序列。克隆了烟草光系统I复合体15.5 kDa亚基的基因，并测定了其核苷酸序列。

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.