期刊
PLANT CELL
卷 28, 期 9, 页码 2147-2160出版社
AMER SOC PLANT BIOLOGISTS
DOI: 10.1105/tpc.16.00428
关键词
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资金
- Ministry of Education, Culture, Sports, Science, and Technology, Japan [15H04381]
- Grants-in-Aid for Scientific Research [15H04381] Funding Source: KAKEN
Pheophytin a is an essential component of oxygenic photosynthetic organisms because the primary charge separation between chlorophyll a and pheophytin a is the first step in the conversion of light energy. In addition, conversion of chlorophyll a to pheophytin a is the first step of chlorophyll degradation. Pheophytin is synthesized by extracting magnesium (Mg) from chlorophyll; the enzyme Mg-dechelatase catalyzes this reaction. In this study, we report that Mendel's green cotyledon gene, STAY-GREEN (SGR), encodes Mg-dechelatase. The Arabidopsis thaliana genome has three SGR genes, SGR1, SGR2, and STAY-GREEN LIKE (SGRL). Recombinant SGR1/2 extracted Mg from chlorophyll a but had very low or no activity against chlorophyllide a; by contrast, SGRL had higher dechelating activity against chlorophyllide a compared with chlorophyll a. All SGRs could not extract Mg from chlorophyll b. Enzymatic experiments using the photosystem and light-harvesting complexes showed that SGR extracts Mg not only from free chlorophyll but also from chlorophyll in the chlorophyll-protein complexes. Furthermore, most of the chlorophyll and chlorophyll binding proteins disappeared when SGR was transiently expressed by a chemical induction system. Thus, SGR is not only involved in chlorophyll degradation but also contributes to photosystem degradation.
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