Korch C, Hagblom P, Ohman H, Göransson M, Normark S
J Bacteriol. 1985 Aug;163(2):430-8. doi: 10.1128/jb.163.2.430-438.1985.
The naturally occurring cryptic plasmid pJD1 of Neisseria gonorrhoeae is 4,207 base pairs long and is found in about 96% of gonococcal strains. The total probable coding capacity of pJD1 was determined from the complete nucleotide sequence by using computational probes to identify open reading frames with similar codon usage and by screening for the presence of ribosomal binding sites before the start codons. Candidates for promoters and terminators were also found in the sequence. Based on these findings, we propose a model for the genetic organization of the plasmid. The model predicts two transcriptional units, each composed of five compactly spaced genes. A promoter of one of the transcripts was shown to function in Escherichia coli, and the products of three of the five genes in this operon were identified in minicell expression experiments. Of these, the cppA gene encoded a 9-kilodalton protein, and the cppB and cppC genes both coded for 24-kilodalton proteins. No expression of the other transcriptional unit was detected, but two genes in this operon were expressed in minicells when transcribed from an E. coli promoter. The experimental data were consistent with the model.
淋病奈瑟菌天然存在的隐蔽质粒pJD1长4207个碱基对，约96%的淋球菌菌株中都能发现它。通过使用计算探针识别具有相似密码子使用情况的开放阅读框，并在起始密码子之前筛选核糖体结合位点，从完整的核苷酸序列确定了pJD1的总可能编码能力。序列中还发现了启动子和终止子的候选序列。基于这些发现，我们提出了该质粒的遗传组织模型。该模型预测有两个转录单元，每个转录单元由五个紧密排列的基因组成。其中一个转录本的启动子在大肠杆菌中具有功能，并且在小细胞表达实验中鉴定了该操纵子中五个基因中的三个基因的产物。其中，cppA基因编码一种9千道尔顿的蛋白质，cppB和cppC基因均编码24千道尔顿的蛋白质。未检测到另一个转录单元的表达，但当从大肠杆菌启动子转录时，该操纵子中的两个基因在小细胞中表达。实验数据与该模型一致。
