Assembly of the Light-Harvesting Chlorophyll Antenna in the Green Alga Chlamydomonas reinhardtii Requires Expression of the TLA2-CpFTSY Gene
Assembly of the Light-Harvesting Chlorophyll Antenna in the Green Alga Chlamydomonas reinhardtii Requires Expression of the TLA2-CpFTSY Gene
复制标题
DOI：
10.1104/pp.111.189910
复制
发表时间：
2012-02-01
期刊：
影响因子：
7.4
通讯作者：
Melis, Anastasios
中科院分区：
文献类型：
--
作者：
Kirst, Henning;Garcia-Cerdan, Jose Gines;Melis, Anastasios
莱茵衣藻的截短光捕获天线 2 (tla2) 突变体表现出较浅绿色的表型，与相应的野生型菌株相比，每个细胞的叶绿素 (Chl) 含量较低，叶绿素 a/b 比值较高。生理分析表明，与野生型相比，tla2 突变体的光合作用饱和度更高，P-max 值更大。生化分析表明，tla2菌株缺乏叶绿素a-b光捕获复合物，其光系统叶绿素天线尺寸仅为野生型的65%左右。分子和遗传分析显示，tla2 菌株中插入了单个质粒，导致染色体 DNA 重排和五个核基因的缺失/破坏。通过绘制插入位点并与每个被删除的基因互补来克隆产生 tla2 表型的 TLA2 基因。莱茵衣藻 TLA2-CpFTSY 基因成功实现了互补，迄今为止尚未研究该基因在绿色微藻中的发生和功能。功能分析表明，核编码和叶绿体定位的 CrCpFTSY 蛋白在叶绿体 a-b 光捕获天线的外围组件的组装中特异性发挥作用。在高等植物中，cpftsy 无效突变抑制光捕获复合体和光系统复合体的组装，从而导致幼苗致死表型。这项工作表明，绿藻中的 cpftsy 缺失可用于产生 tla 突变体，但高等植物中则不然。后者在大众培养和明亮的阳光条件下表现出提高的太阳能转换效率和光合生产力。
The truncated light-harvesting antenna2 (tla2) mutant of Chlamydomonas reinhardtii showed a lighter-green phenotype, had a lower chlorophyll (Chl) per-cell content, and higher Chl a/b ratio than corresponding wild-type strains. Physiological analyses revealed a higher intensity for the saturation of photosynthesis and greater P-max values in the tla2 mutant than in the wild type. Biochemical analyses showed that the tla2 strain was deficient in the Chl a-b light-harvesting complex, and had a Chl antenna size of the photosystems that was only about 65% of that in the wild type. Molecular and genetic analyses showed a single plasmid insertion in the tla2 strain, causing a chromosomal DNA rearrangement and deletion/disruption of five nuclear genes. The TLA2 gene, causing the tla2 phenotype, was cloned by mapping the insertion site and upon complementation with each of the genes that were deleted. Successful complementation was achieved with the C. reinhardtii TLA2-CpFTSY gene, whose occurrence and function in green microalgae has not hitherto been investigated. Functional analysis showed that the nuclear-encoded and chloroplast-localized CrCpFTSY protein specifically operates in the assembly of the peripheral components of the Chl a-b light-harvesting antenna. In higher plants, a cpftsy null mutation inhibits assembly of both the light-harvesting complex and photosystem complexes, thus resulting in a seedling-lethal phenotype. The work shows that cpftsy deletion in green algae, but not in higher plants, can be employed to generate tla mutants. The latter exhibit improved solar energy conversion efficiency and photosynthetic productivity under mass culture and bright sunlight conditions.