Wellington C L, Beatty J T
Department of Microbiology, University of British Columbia, Vancouver, Canada.
J Bacteriol. 1991 Feb;173(4):1432-43. doi: 10.1128/jb.173.4.1432-1443.1991.
The crtEF, bchCA, and puf operons of the facultative phototrophic bacterium Rhodobacter capsulatus encode gene products that are necessary for the formation of various components of the photosynthetic apparatus. The crtEF operon encodes two enzymes involved in the biosynthesis of carotenoids, the bchCA operon codes for two enzymes of the bacteriochlorophyll biosynthetic pathway, and the puf operon encodes four pigment-binding polypeptides as well as two polypeptides with less well understood functions. These three operons are adjacent to one another on the chromosome and are transcribed in the same direction. We present the results of RNA blotting and S1 nuclease protection end-mapping experiments which provide direct evidence that the mRNA transcripts of these three operons overlap. Therefore, it is likely that the crtEF, bchCA, and puf operons can be expressed as a single transcriptional unit, although RNA polymerase may initiate transcription at any of several promoters.
兼性光合细菌荚膜红细菌（Rhodobacter capsulatus）的crtEF、bchCA和puf操纵子编码光合装置各种组分形成所必需的基因产物。crtEF操纵子编码参与类胡萝卜素生物合成的两种酶，bchCA操纵子编码细菌叶绿素生物合成途径的两种酶，puf操纵子编码四种色素结合多肽以及两种功能尚不太清楚的多肽。这三个操纵子在染色体上彼此相邻，并按相同方向转录。我们展示了RNA印迹和S1核酸酶保护末端作图实验的结果，这些结果提供了直接证据，证明这三个操纵子的mRNA转录本相互重叠。因此，尽管RNA聚合酶可能在几个启动子中的任何一个处起始转录，但crtEF、bchCA和puf操纵子很可能可以作为一个单一的转录单元进行表达。
