Functional analysis of two maize cDNAs encoding T7-like RNA polymerases

作     者：Chang, CC Sheen, J Bligny, M Niwa, Y Lerbs-Mache, S Stern, DB 

作者机构：Cornell Univ Boyce Thompson Inst Plant Res Ithaca NY 14853 USA Harvard Univ Sch Med Dept Genet Boston MA 02114 USA Massachusetts Gen Hosp Dept Biol Mol Boston MA 02114 USA Univ Grenoble 1 Lab Genet Mol Plantes F-38041 Grenoble 9 France Univ Shizuoka Sch Food & Nutrit Sci Shizuoka 422 Japan 

出 版 物：《PLANT CELL》 (植物细胞)

年 卷 期：1999年第11卷第5期

页      面：911-926页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学] 

基　　金：NIGMS NIH HHS [R01GM52560] Funding Source: Medline 

主　　题：氨基酸序列 细胞区室化 叶绿体/酶学 克隆 分子 保守序列 DNA 互补/遗传学 指导DNA的RNA聚合酶类/遗传学 指导DNA的RNA聚合酶类/分离和提纯 指导DNA的RNA聚合酶类/代谢 基因剂量 绿色荧光蛋白质类 发光蛋白质类/遗传学 发光蛋白质类/分离和提纯 线粒体/酶学 分子序列数据 RNA 信使/生物合成 RNA 信使/遗传学 RNA 植物/生物合成 RNA 植物/遗传学 重组融合蛋白质类/分离和提纯 序列同源性 氨基酸 组织分布 病毒蛋白质类 玉米/酶学 玉米/遗传学 

摘      要：We have characterized two maize cDNAs, rpoTm and rpoTp, that encode putative T7-like RNA polymerases. In vivo cellular localization experiments using transient expression of the green fluorescent protein suggest that their encoded proteins are targeted exclusively to mitochondria and plastids, respectively. An antibody raised against the C terminus of the rpoTp gene product identified mitochondrial polypeptides of similar to 100 kD. Their presence was correlated with RNA polymerase activity, and the antibody inhibited mitochondrial in vitro transcription activity. Together, these results strongly suggest that the product of rpoTm is involved in maize mitochondrial transcription. By contrast, immunoblot analysis and an antibody-linked polymerase assay indicated that rpoTp specifies a plastid RNA polymerase component. A quantitative reverse transcription-polymerase chain reaction assay was used to study the transcription of rpoTp and rpoTm in different tissues and under different environmental conditions. Although both genes were constitutively expressed, rpoTm transcripts were generally more prevalent in nonphotosynthetic tissues, whereas an increase in rpoTp transcripts paralleled chloroplast development. We suggest that these two genes encode constitutive components of the organelle transcription machinery but that their expression is nonetheless subject to modulation during plant development.