Molecular Cloning of the Family of Glutamine Synthetase Genes from Maize: Expression of Genes for Glutamine Synthetase and Ferredoxin-Dependent Glutamate Synthase in Photosynthetic and Non-Photosynthetic Tissues
Molecular Cloning of the Family of Glutamine Synthetase Genes from Maize: Expression of Genes for Glutamine Synthetase and Ferredoxin-Dependent Glutamate Synthase in Photosynthetic and Non-Photosynthetic Tissues
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DOI：
10.1093/oxfordjournals.pcp.a078219
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发表时间：
1992
影响因子：
4.9
通讯作者：
H. Sakakibara;S. Kawabata;H. Takahashi;T. Hase;T. Sugiyama
中科院分区：
文献类型：
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作者：
H. Sakakibara;S. Kawabata;H. Takahashi;T. Hase;T. Sugiyama
从玉米光诱导绿化叶片的poly（A）+RNA构建的cDNA文库中分离到5个谷氨酰胺合成酶（GS）的cDNA克隆，分别为pGS 107、pGS 112、pGS 117、pGS 122和pGS 202。从一级结构的比较，pGS 202被判断为编码质体同种型，而其他编码胞质同种型。这一结果证实，玉米GS是由一个小的多基因家族编码，在其他植物物种的情况下。通过Western和北方印迹法分析了GS亚型和铁氧还蛋白依赖性谷氨酸合酶（Fd-GOGAT）在不同器官（即叶、中胚轴和根）和各种生理条件下的蛋白质和mRNA的稳态水平。质体GS和Fd-GOGAT和它们各自的mRNA的水平在光合器官中比在非光合器官中高得多，并且在黄化叶片的光照期间以类似的方式增加。因此，质体GS和Fd-GOGAT在叶片中的表达似乎在转录水平上协调调节。虽然GS的胞质异构体，由四个单独的基因编码不能分别定量，其各自的mRNA的水平是非常不同的。与pGS 107和pGS 112相对应的mRNA含量丰富，几乎均匀地分布在所有器官中，而与pGS 117和pGS 122相对应的mRNA主要分别分布在年轻的黄化叶和根中。
Five cDNA clones for glutamine synthetase (GS), pGS107, pGS112, pGS117, pGS122, and pGS202, were isolated from a maize cDNA library constructed with poly(A)+RNA from lightinduced greening leaves. From a comparison of the primary structures, pGS202 was judged to encode a plastidic isoform, and the others to encode cytosolic isoforms. This result confirms that maize GS is encoded by a small multigene family, as is the case in other plant species. Steadystate levels of proteins and mRNAs for the GS isoforms and ferredoxin-dependent glutamate synthase (Fd-GOGAT) were analysed by Western and Northern blottings in different organs, namely, leaves, mesocotyls and roots, and under various physiological conditions. The levels of both plastidic GS and Fd-GOGAT and those of their respective mRNAs were much higher in photosynthetic organs than in non-photosynthetic organs and increased in a similar manner during illumination of etiolated leaves. Thus, the expression of the plastidic GS and Fd-GOGAT in leaves seems to be coordinately regulated at the transcriptional level. Although the cytosolic isoforms of GS, encoded by the four separate genes could not be quantified separately, the levels of their respective mRNAs were very different from one another. The mRNAs that corresponded to pGS107 and pGS112 were abundant and were distributed almost equally in all organs, while those that corresponded to pGS117 and pGS122 were distributed predominantly in young etiolated leaves and roots, respectively.