Cascade regulation of Caulobacter flagellar and chemotaxis genes.
Cascade regulation of Caulobacter flagellar and chemotaxis genes.
复制标题
柄杆菌鞭毛和趋化基因的级联调节。
DOI：
10.1016/0022-2836(87)90716-9
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发表时间：
1987
影响因子：
5.6
通讯作者：
Shapiro,L
中科院分区：
文献类型：
--
作者：
Champer,R;Dingwall,A;Shapiro,L
新月茎杆菌中功能性鞭毛的组装需要大约 30 个基因的蛋白质产物，这些基因以时间上离散和空间上不同的方式表达。我们目前对该系统的理解受到以下事实的限制：纯化的蛋白质产品仅适用于其中约五分之一的基因。基因工程转座子启动子探针 Tn5-VB32，含有编码新霉素磷酸转移酶 II (NPTase II) 的无启动子基因，用于产生一系列非运动 (fla-)、卡那霉素抗性菌株。新月形。这些转录融合允许鞭毛启动子控制 NPTase II 的表达，因此可以解决鞭毛基因的时间调控问题，而无需获得纯化的蛋白质产物。 Tn5-VB32 访问的鞭毛启动子表现出类似于已知的鞭毛和趋化性基因产物的时间调节。这些突变体中 NPTase II 的表达是从嵌合 mRNA 中读取的，该 mRNA 起始于染色体fla启动子，并继续通过插入的 NPTase II 基因。因此，时间调节是通过在细胞周期的特定时间调节转录的起始或转录本周转来控制的。在通过将启动子探针突变转导到自发衍生的第二位点突变体背景中而产生的双突变体中，研究了启动子探针访问的基因与其他鞭毛基因座之间的上位相互作用。使用纯化鞭毛成分和纯化 NPTase II 的抗血清在这些菌株中测定天然鞭毛基因产物和获得的 NPTase II 的合成。在这些相互作用的基础上，提出了鞭毛和趋化性基因表达的反式作用层次。
The assembly of a functional flagellum in the bacteriumCaulobacter crescentusrequires the protein products of approximately 30 genes expressed in a temporally discrete and spatially distinct manner. Our current understanding of this system has been limited by the fact that purified protein products are available for only about one-fifth of these genes. A genetically engineered transposon promoter probe, Tn5-VB32, containing a promoterless gene encoding neomycin phosphotransferase II (NPTase II) was used to generate a series of non-motile (fla−), kanamycin resistant strains ofC. crescentus. These transcription-fusions allow the expression of NPTase II to be controlled by flagellar promoters, and thus questions of temporal regulation of flagellar genes can be addressed without the need to obtain purified protein products. The flagellar promoters accessed by Tn5-VB32 exhibited temporal regulation analogous to the known flagellar and chemotaxis gene products. The expression of NPTase II in these mutants is read from a chimeric mRNA that initiates in a chromosomalflapromoter and continues through the inserted NPTase II gene. Thus, temporal regulation is controlled by modulating either the initiation of transcription, or transcript turnover, at specific times in the cell cycle.Epistatic interactions between the genes accessed by the promoter probe and other flagellar loci were studied in doubleflamutants generated by transducing the promoterprobe mutations into spontaneously derived second-sitefla-mutant backgrounds. The synthesis of both naturalflagene products and the accessed NPTase II was assayed in these strains using antisera to purified components of the flagellum and to purified NPTase II. On the basis of these interactions, atrans-acting hierarchy of flagellar and chemotaxis gene expression is proposed.