Light-stimulated accumulation of the peroxisomal enzymes hydroxypyruvate reductase and serine:glyoxylate aminotransferase and their translatable mRNAs in cotyledons of cucumber seedlings
Light-stimulated accumulation of the peroxisomal enzymes hydroxypyruvate reductase and serine:glyoxylate aminotransferase and their translatable mRNAs in cotyledons of cucumber seedlings
复制标题
光刺激黄瓜幼苗子叶中过氧化物酶体酶羟基丙酮酸还原酶和丝氨酸：乙醛酸转氨酶及其可翻译mRNA的积累
DOI：
10.1007/bf00166462
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发表时间：
1987
影响因子：
5.1
通讯作者：
W. M. Becker
中科院分区：
文献类型：
--
作者：
D. Hondred;Dawn;D. Titus;W. M. Becker
黄瓜幼苗子叶中过氧化物酶体酶的发育强烈地依赖于光。在光生长的幼苗，过氧化物酶体的两种酶，羟基丙酮酸还原酶（HPR）和丝氨酸：乙醛酸转氨酶（SGAT）的活动，几乎检测不到，直到3天postimbibition后，这段时间后，这两种活动迅速增加，线性至少3天。在黑暗中，这些酶的活性在同一时间段内略有增加，但仅为7天光诱导水平的约5%至10%。当黑暗生长5 1/2天的幼苗转入白色光下时，HPR和SGAT活性在约8 h后开始升高。HPR蛋白的免疫沉淀试验表明，增加同时与酶的活性在光明和黑暗生长的子叶。免疫印迹结果表明，SGAT的两个亚基SGAT-A和SGAT-B的含量也沿着SGAT活性的增加而增加。编码HPR，SGAT-A和SGAT-B的可翻译mRNA的相对水平也是光依赖性的，并且随着类似于光和暗生长的子叶中的酶活性和蛋白质水平的发育模式而增加。在51/2天的黑暗生长的子叶转移到光，SGAT-A和SGAT-B的可翻译的mRNA开始增加1小时内的照明，并继续增加迅速和线性为下一个24小时的光到一个新的稳态水平，是黑暗对照的45倍。可翻译的HPR mRNA表现出双相模式的积累，在第一个6小时的照明期间增加了3倍，随后在8和24小时之间增加了6倍。两种酶的抑制活性mRNA的积累先于相应蛋白质和酶活性的积累约8 h。我们的数据表明，酶活性的上升取决于这些酶的可翻译mRNA的增加，并在翻译前水平进行调节，最有可能涉及新mRNA的转录。
The development of peroxisomal enzymes in cotyledons of cucumber seedlings is strongly dependent on light. In light-grown seedlings, activities of two peroxisomal enzymes, hydroxypyruvate reductase (HPR) and serine: glyoxylate aminotransferase (SGAT), were barely detectable until three days postimbibition, after which time both activities increased rapidly and linearly for at least three days. In the dark, the activities of these enzymes increased slightly over the same time period, but only to about 5% to 10% of 7-day light-induced levels. When 51/2-day dark-grown seedlings were transferred into white light, activities of HPR and SGAT began to increase after approximately 8 h. HPR protein was shown by an immunoprecipitation assay to increase concurrently with enzymatic activity in both light- and dark-grown cotyledons. Immunoblotting results suggested that the amounts of SGAT-A and SGAT-B, the two subunits of SGAT, also developed along with SGAT activity. The relative levels of translatable mRNAs encoding HPR, SGAT-A, and SGAT-B were also light-dependent, and increased with a developmental pattern similar to enzyme activity and protein levels in light- and dark-grown cotyledons. In 51/2-day dark-grown cotyledons that were transferred to the light, translatable mRNAs for SGAT-A and SGAT-B began to increase within 1 h of illumination and continued of increase rapidly and linearly for the next 24 h in the light to a new steady-state level that was 45 times that of dark controls. Translatable HPR mRNA exhibited a biphasic pattern of accumulation, with a three-fold increase during the first 6 h of illumination, followed by an additional six-fold increase between 8 and 24 h. The accumulation of translationally active mRNA for both enzymes preceded the accumulation of the corresponding protein and enzyme activity by about 8 h. Our data suggest that the rise in enzyme activity depends on an increase in translatable mRNA for these enzymes and is regulated at a pretranslational level, most likely involving transcription of new mRNA.