Nierzwicki-Bauer S A, Curtis S E, Haselkorn R
Proc Natl Acad Sci U S A. 1984 Oct;81(19):5961-5. doi: 10.1073/pnas.81.19.5961.
In the filamentous cyanobacterium Anabaena, the gene for the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase is linked to and transcribed together with the gene encoding the large subunit (rbcL) of the same enzyme. The two genes are separated by a spacer of 545 base pairs (bp) that does not contain an open reading frame. Both genes hybridize with a predominant 3.1-kilobase transcript that initiates 414 bp upstream from the rbcL coding region. The nucleotide sequence 14-8 bp preceding the transcription start site resembles a good Escherichia coli promoter, but the sequence in the -35 region does not. There is no obvious relationship between the sequence flanking the amino terminus of the cyanobacterial small subunit gene and the transit peptide of eukaryotic small subunit genes. The Anabaena rbcS gene is 61% homologous at the amino acid level with the gene from the unicellular cyanobacterium Anacystis and 37-38% homologous with the corresponding nuclear genes from eukaryotes. In contrast, the Anabaena rbcL gene is approximately equal to 86% homologous at the amino acid level with the rbcL genes from plant chloroplasts. Cotranscription satisfies one of the requirements for coordinate expression of the two genes whose products are needed in equimolar amounts in the mature enzyme. The rbcL-rbcS transcript is equally abundant in Anabaena azollae grown in the light or on fructose in the dark.
在丝状蓝细菌鱼腥藻中，1,5 - 二磷酸核酮糖羧化酶小亚基（rbcS）的基因与编码同一酶大亚基（rbcL）的基因相连并一起转录。这两个基因被一个545个碱基对（bp）的间隔区隔开，该间隔区不包含开放阅读框。两个基因都与一个主要的3.1千碱基转录本杂交，该转录本在rbcL编码区上游414 bp处起始。转录起始位点前14 - 8 bp的核苷酸序列类似于一个良好的大肠杆菌启动子，但 - 35区域的序列并非如此。蓝细菌小亚基基因氨基末端侧翼序列与真核小亚基基因的转运肽之间没有明显关系。鱼腥藻rbcS基因在氨基酸水平上与单细胞蓝细菌集胞藻的基因有61%的同源性，与真核生物相应的核基因有37 - 38%的同源性。相比之下，鱼腥藻rbcL基因在氨基酸水平上与植物叶绿体的rbcL基因约有86%的同源性。共转录满足了两个基因协调表达的一个要求，这两个基因的产物在成熟酶中需要等摩尔量。rbcL - rbcS转录本在光照下生长的满江红鱼腥藻或黑暗中以果糖为碳源生长的满江红鱼腥藻中含量相同。
