拟南芥中近来发现的定位于叶绿体的膜嵌合金属蛋白酶EGY1影响叶绿体发育与脂肪酸合成,经生物信息学分析,集胞藻PCC6803(Synechocystis sp.PCC6803)中slr0643、sll0862基因编码同源蛋白.[目的]为了鉴定这两个基因的功能,[方法]本文通过同源重组插入卡那霉素抗性基因、切断目的基因,分别构建了slr0643::km和sll0862::km两种突变体,检测突变体的生理生化表型.[结果]在30℃,20μE/m~2s自养培养下,slr0643::km与野生型相比,早期生长速率相近,但77K叶绿素荧光显示,光合系统Ⅰ含量降低,光合系统Ⅰ与Ⅱ的比率明显降低,光合电子传递链的全链速率仅为野生型的83%.电镜结果显示胞内膜系统完好.sll0862::km的形态、生长速率、光合系统Ⅰ与Ⅱ的比率以及内膜结构均与野生型无明显差异.[结论]可见在本实验条件下,生长早期,两个基因的功能有所不同,slr0643参与了光合系统的合成及光合作用的精细调控,而sll0862并不直接影响光合系统功能.研究结果为进一步阐明不同条件下集胞藻PCC6803中EGY基因家族各个成员的功能和作用机理奠定了基础.%Recently a novel membrane-associated metaUoprotease EGY1 was found to localize in the chloroplast of Arabidospis and is required for chloroplast development and fatty acid biosynthesis. The genes slr0643 and sU0862 from cyanobactefia Synechocystis sp. PCC6803 encode EGY1 homologs.[Objective] For functions] characterization of these two genes,[Methods] disrupted mutants slr0643: :km and sll0862: :km were constructed by homologous recombination. [Results] Under 30 degree, normal light and autotrophic growth, compared with wild type, slr0643: :kin showed similar growth rate in the early stage, but emitted less photosystem Ⅰ(PSI) fluorescence under 77K and the activity of the entire photosynthetic electron transfer chain was only 83 % of the wild type, while cells contained normal thylakoid membranes. No significant difference was found between sU0862 : : km and wild type under this condition. [Conclusion] These results indicated that sir0643 was involved in PSI assembly and photosynthesis directly while sU0862 did not affect assembly of PSI and PSⅡ directly at this stage, which lay a foundation for further exploring their function and meehnism in cyanobacteria.
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