Champer R, Bryan R, Gomes S L, Purucker M, Shapiro L
Cold Spring Harb Symp Quant Biol. 1985;50:831-40. doi: 10.1101/sqb.1985.050.01.101.
Each Caulobacter cell division yields daughter cells that differ from one another both structurally and functionally. By focusing on the biogenesis of the polar flagellum and the proteins of the chemosensory system, several laboratories have now defined an extensive network of genes whose temporal expression is controlled in the predivisional cell. The differential turn-on of these genes contributes to the generation of asymmetry in the predivisional cell in that the products of these genes are targeted to specific cellular locations. To define the mechanisms that mediate this temporal and spatial control, fla genes whose products are not known were accessed by the insertion of transposon-carried drug resistance markers. The transposons were altered so that upon insertion into the chromosome, transcription fusions are formed in which the promoter regions of fla genes drive the expression of the downstream promoter-less drug resistance genes. Assays of the differential placement of the promoter-less drug resistance proteins (encoded within the interrupted fla genes) allow us to determine whether the positioning of the fla gene products is controlled by signal sequences in their proteins, by specific mRNA-targeting sequences in the 5'-regulatory regions of these genes, or by specific transcription from only one of the two newly replicated chromosomes in the predivisional cell.
每个柄杆菌细胞分裂产生的子细胞在结构和功能上都彼此不同。通过聚焦于极鞭毛的生物发生和化学感受系统的蛋白质，现在有几个实验室已经确定了一个广泛的基因网络，其时间表达在分裂前细胞中受到控制。这些基因的差异开启有助于在分裂前细胞中产生不对称性，因为这些基因的产物被靶向特定的细胞位置。为了确定介导这种时间和空间控制的机制，通过插入携带转座子的耐药标记来研究其产物未知的鞭毛（fla）基因。对转座子进行了改造，使其插入染色体后形成转录融合体，其中fla基因的启动子区域驱动下游无启动子耐药基因的表达。对无启动子耐药蛋白（由中断的fla基因编码）的差异定位分析，使我们能够确定fla基因产物的定位是否由其蛋白质中的信号序列、这些基因5'调控区域中的特定mRNA靶向序列，或由分裂前细胞中两条新复制染色体中仅一条的特定转录所控制。
