Developmental and circadian control of the capacity for delta-aminolevulinic acid synthesis in green barley
Developmental and circadian control of the capacity for delta-aminolevulinic acid synthesis in green barley
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DOI：
10.1007/s004250050124
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发表时间：
1997-06-01
期刊：
影响因子：
4.3
通讯作者：
Kloppstech, K
中科院分区：
文献类型：
--
作者：
Kruse, E;Grimm, B;Kloppstech, K
δ-氨基乙酰丙酸（delta-ALA）的合成是四吡咯合成调控的关键步骤。为了研究协调叶绿素和叶绿素结合蛋白合成的发育和昼夜节律钟控制机制，分析了在黑暗：光照或恒定光照条件下生长的大麦（Hordeum vulgare L.）初生叶中δ-ALA合成能力。δ-ALA形成活性在24 h内振荡，在黑暗到光明的过渡期达到最大值，12 h后达到最小值，表明昼夜节律振荡器在发育过程中的参与。在大麦初生叶中部，δ-ALA的合成能力短暂增加。δ-ALA形成活性与之前发表的捕光叶绿素结合蛋白mRNA在空间和时间上的稳态水平密切相关;这支持了叶绿素和色素结合蛋白协同合成的观点。稳态水平的mRNA编码的三种酶的δ-ALA合成途径和蛋白质的谷氨酰-tRNA还原酶（GluTR）和谷氨酸1-半醛氨基转移酶（GSA AT; EC 5.4.3.8）进行了分析，其发育和昼夜表达在大麦叶。GluTR mRNA和蛋白质的含量与δ-ALA形成活性的变化平行。GSA AT mRNA的水平在相反的相位振荡，但蛋白质含量没有表现出实质性的振荡昼夜生长条件下。未检测到谷氨酰tRNA合酶（GluRS; EC 6.1.1.17）的昼夜节律振荡。在大麦初生叶的中部（第3和4段）观察到最大的GluTR mRNA含量和蛋白质。因此，GluTR的发育控制表达不同于GSA AT和GluRS，但类似于大麦叶梯度中δ-ALA合成的能力。这些数据表明，振荡，光依赖性和空间表达的GluTR mRNA可能有助于调节形成的叶绿素前体δ-ALA。
The synthesis of delta-aminolevulinic acid (delta-ALA) is a key step in the regulation of tetrapyrrole synthesis. To study the developmentally and circadian-clock controlled mechanism that co-ordinates synthesis of chlorophylls and chlorophyll-binding proteins, delta-ALA-synthesising capacity was analysed in barley (Hordeum vulgare L,) primary leaves grown under dark: light or constant light conditions. The delta-ALA-forming activity oscillated within 24 h with a maximum at the transition of dark to light and a minimum 12 h later, indicating the involvement of the circadian oscillator during development. The capacity for delta-ALA synthesis increased transiently in the middle of barley primary leaves. The delta-ALA-forming-activity correlated well with the previously published steady-state level of mRNA for light-harvesting chlorophyll-binding proteins in space and time; this supports the view of a co-ordinate synthesis of chlorophyll and pigment-binding proteins. Steady-state levels of mRNAs encoding the three enzymes of the delta-ALA-synthesising pathway and of proteins for glutamyl-tRNA reductase (GluTR) and glutamate 1-semialdehyde aminotransferase (GSA AT; EC 5.4.3.8) were analysed for their developmental and circadian expression in barley leaves. The contents of GluTR mRNA and protein cycled parallel to the changes in delta-ALA-forming activity. The levels of GSA AT mRNA oscillated in an opposite phase, but the protein content did not show substantial oscillation under diurnal and circadian growth conditions. No circadian oscillation was detected for glutamyl tRNA synthase (GluRS; EC 6.1.1.17). Maximal GluTR mRNA content and protein was observed in the middle (segments 3 and 4) of the barley primary leaves. The developmentally controlled expression of GluTR therefore differs from that of GSA AT and GluRS, but resembles the capacity for delta-ALA synthesis in a barley leaf gradient. These data indicate that the oscillating, light-dependent and spatial expression of GluTR mRNA might contribute to the regulated formation of the chlorophyll precursor delta-ALA.