Loss of the N-terminal domain of chlorophyllide a oxygenase induces photodamage during greening of Arabidopsis seedlings.
Loss of the N-terminal domain of chlorophyllide a oxygenase induces photodamage during greening of Arabidopsis seedlings.
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DOI：
10.1186/1471-2229-8-64
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发表时间：
2008-06-12
影响因子：
5.3
通讯作者：
Tanaka A
中科院分区：
文献类型：
--
作者：
Yamasato A;Tanaka R;Tanaka A
叶绿素 b 是绿色植物中主要的光合色素，由叶绿素 a 加氧酶 (CAO) 合成。叶绿素 b 生物合成的调节是光系统天线尺寸的重要决定因素。叶绿素 b 的合成在转录水平上部分受 CAO 基因表达的调节。此外，叶绿素 b 的合成在蛋白质水平上受到 CAO 酶稳定性的严格调控。 CAO由三个结构域组成，从N末端开始依次命名为A、B和C结构域。 CAO的A结构域参与CAO蛋白稳定性的调节。为了阐明A结构域的生理功能，我们构建了转基因拟南芥（Arabidopsis thaliana）植物，其过表达完整的CAO或缺乏A结构域的CAO的截短版本。过度表达A结构域缺失的CAO的转基因植物在绿化过程中积累了过量的叶绿素b。缺乏A结构域的转基因植物在黄化后立即暴露于连续光照时要么死亡，要么明显迟缓。此外，CAO中A结构域的缺失损害了叶绿素生物合成的另一个步骤，即在黑暗条件下二乙烯基原叶绿素a转化为单乙烯基原叶绿素a。 CAO的A结构域调节CAO的水平，从而防止叶绿素b的过量积累。 A结构域的这一功能在黄化幼苗的绿化阶段尤其重要。在此阶段，植物很容易受到光损伤，这可能是由于叶绿素 b 积累过多造成的。此外，CAO水平的失调会通过未知的机制影响黑暗中单乙烯基原叶绿素内酯的生物合成。总之，CAO 的 A 结构域对于叶绿素生物合成的控制以及去黄化过程中幼苗的存活（尤其是在强光照下）至关重要。
Chlorophyll b is a major photosynthetic pigment in green plants that is synthesized by chlorophyllide a oxygenase (CAO). The regulation of chlorophyll b biosynthesis is an important determinant for the antenna size of photosystems. Chlorophyll b synthesis is partly regulated on a transcriptional level by the expression of the CAO gene. In addition, the synthesis of chlorophyll b is strictly regulated on a protein level by the stability of the CAO enzyme. CAO consists of three domains, which are sequentially named from the N terminus as the A, B and C domains. The A domain of CAO participates in the regulation of the CAO protein stability. In order to clarify the physiological function of the A domain, we constructed transgenic Arabidopsis (Arabidopsis thaliana) plants which either overexpressed the complete CAO or a truncated version of CAO lacking the A domain. The transgenic plants overexpressing the A-domain-deleted CAO accumulated an excess amount of chlorophyll b during greening. The transgenic plants which lacked the A domain either died or were obviously retarded when they were exposed to continuous light immediately after etiolation. In addition, the loss of the A domain in CAO impaired another step of chlorophyll biosynthesis, namely the conversion of divinyl-protochlorophyllide a to monovinyl protochlorophyllide a under dark conditions. The A domain of CAO regulates the level of CAO, and thus prevents the excess accumulation of chlorophyll b. This function of the A domain is especially important during the greening stage of etiolated seedlings. At this stage, the plants are vulnerable to photodamages which could be caused by excessive chlorophyll b accumulation. In addition, de-regulation of the CAO level affects monovinyl-protochlorophyllide biosynthesis in darkness by unknown mechanisms. In conclusion, the A domain of CAO is essential in the control of chlorophyll biosynthesis and in the survival of seedlings during de-etiolation especially under strong illumination.
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影响因子：
4.9
作者：
Nagata, Nozomi;Tanaka, Ryouichi;Tanaka, Ayumi
通讯作者：
Tanaka, Ayumi
DOI：
10.1073/pnas.0307284101
发表时间：
2004-02-17
影响因子：
11.1
作者：
Reinbothe, S;Quigley, F;Reinbothe, C
通讯作者：
Reinbothe, C
影响因子：
2.5
作者：
Zapata, M;Rodríguez, F;Garrido, JL
通讯作者：
Garrido, JL
DOI：
10.1073/pnas.95.21.12719
发表时间：
1998-10-13
影响因子：
11.1
作者：
Tanaka, A;Ito, H;Okada, K
通讯作者：
Okada, K
影响因子：
7.2
作者：
Oster, U;Tanaka, R;Rüdiger, W
通讯作者：
Rüdiger, W