Role of Arabidopsis CHL27 protein for photosynthesis, chloroplast development and gene expression profiling
Role of Arabidopsis CHL27 protein for photosynthesis, chloroplast development and gene expression profiling
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DOI：
10.1093/pcp/pcn111
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发表时间：
2008-09-01
影响因子：
4.9
通讯作者：
Bahk, Jeong Dong
中科院分区：
文献类型：
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作者：
Bang, Woo Young;Jeong, In Sil;Bahk, Jeong Dong
在叶绿素生物合成中，需氧镁原卟啉 IX 单甲酯 (MPE) 环化酶是参与原叶绿素 a 合成的关键酶，其膜结合成分已知由光合细菌、绿藻和植物中 CHL27 的同系物编码。在这里，我们报道拟南芥 chl27-t 敲低突变体表现出生长迟缓和叶绿体发育缺陷，这是由 PSII 反应中心受损引起的。该突变体在 CHL27 启动子内包含 T-DNA 插入，可显着降低 CHL27 mRNA 水平。 Chl27-t 突变体植物生长缓慢，外观呈淡绿色，表明它们在叶绿素生物合成方面存在缺陷。 Chl 荧光分析显示 Chl27-t 突变体的光合活性显着降低，表明其 PSII 反应中心受损。 Chl27-t 突变还导致叶绿体发育出现严重缺陷，包括类囊体膜的解开。 Chl27-t突变体的微阵列分析显示，许多参与光合作用的核基因受到抑制，包括那些编码光捕获复合物I (LHCI)和LHCII、PSI和PSII成分的基因，这解释了光合作用活性和叶绿体发育的缺陷。此外，微阵列数据还揭示了诸如PORA和AtFRO6等基因分别对叶绿素生物合成和铁获取的显着抑制，并且进一步暗示PORA、AtFRO6和CHL27蛋白之间在叶绿素生物合成途径中存在串扰。
In Chl biosynthesis, aerobic Mg-protoporphyrin IX monomethyl ester (MPE) cyclase is a key enzyme involved in the synthesis of protochlorophyllide a, and its membrane-bound component is known to be encoded by homologs of CHL27 in photosynthetic bacteria, green algae and plants. Here, we report that the Arabidopsis chl27-t knock-down mutant exhibits retarded growth and chloroplast developmental defects that are caused by damage to PSII reaction centers. The mutant contains a T-DNA insertion within the CHL27 promoter that dramatically reduces the CHL27 mRNA level. chl27-t mutant plants grew slowly with a pale green appearance, suggesting that they are defective in Chl biosynthesis. Chl fluorescence analysis showed significantly low photosynthetic activity in chl27-t mutants, indicating damage in their PSII reaction centers. The chl27-t mutation also conferred severe defects in chloroplast development, including the unstacking of thylakoid membranes. Microarray analysis of the chl27-t mutant showed repression of numerous nuclear genes involved in photosynthesis, including those encoding components of light-harvesting complex I (LHCI) and LHCII, and PSI and PSII, which accounts for the defects in photosynthetic activity and chloroplast development. In addition, the microarray data also revealed the significant repression of genes such as PORA and AtFRO6 for Chl biosynthesis and iron acquisition, respectively, and, furthermore, implied that there is cross-talk in the Chl biosynthetic pathway among the PORA, AtFRO6 and CHL27 proteins.