The Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138.
Proc Natl Acad Sci U S A. 1981 Nov;78(11):6821-5. doi: 10.1073/pnas.78.11.6821.
The transcription of cloned maize plastid DNA sequences in vitro by maize plastid DNA-dependent RNA polymerase has been studied to expose the roles of the enzyme, polypeptide cofactors, and DNA sequences in the regulation of gene expression. The 4.35-kilobase pair BamHI fragment 9 carries the maize plastid gene for the large subunit of ribulosebisphosphate carboxylase and part of the gene for a 2.2-kilobase RNA. These two genes are separated by approximately 330 base pairs and are transcribed divergently. Transcripts of the gene for the large subunit of ribulosebisphosphate carboxylase are abundant in bundle sheath cells of maize leaves and we show here that transcripts of the 2.2-kilobase RNA gene are present in both mesophyll cells and the adjacent bundle sheath cells. In vitro, in the presence of the S factor, maize chloroplast DNA-dependent RNA polymerase produces a transcript of the gene for the large subunit of ribulose-bisphosphate carboxylase with a 5' terminus like that of the corresponding mRNA isolated from plastids, transcribes chloroplast DNA sequences of Bam fragment 9 in a chimeric plasmid in preference to the vehicle RSF 1030 and, in a ratio of 3:1, preferentially transcribes the gene for the large subunit of ribulosebisphosphate carboxylase over the 2.2-kilobase RNA gene from supercoiled chimeric plasmid DNA.
体外转录克隆的玉米质体 DNA 序列的研究，以揭示酶、多肽辅助因子和 DNA 序列在基因表达调控中的作用。4.35 千碱基对的 BamHI 片段 9 携带玉米质体基因的大亚基和部分 2.2 千碱基 RNA 基因。这两个基因被大约 330 个碱基对隔开，并以相反的方向转录。玉米叶片的束鞘细胞中富含 RuBP 羧化酶大亚基基因的转录本，我们在这里表明，2.2kb RNA 基因的转录本存在于叶肉细胞和相邻的束鞘细胞中。在体外，在 S 因子的存在下，玉米叶绿体 DNA 依赖性 RNA 聚合酶产生一个 RuBP 羧化酶大亚基基因的转录本，其 5'末端与从质体中分离的相应 mRNA 相同，在嵌合质粒中优先转录 Bam 片段 9 的叶绿体 DNA 序列，而不是载体 RSF 1030，并以 3:1 的比例优先转录超螺旋嵌合质粒 DNA 上的 RuBP 羧化酶大亚基基因，而不是 2.2kb RNA 基因。
