REGULATION OF DEVELOPMENTAL GENES IN CAULOBACTER

新月柄杆菌具有明确的生命周期， 细胞反复不对称分裂，产生柄状细胞， 一个新的蜂群细胞，它携带着一系列的表面结构， 包括一个鞭毛、皮利和一个固着器;所有这些结构都 在细胞周期的离散时间组装在茎远端极。 鞭毛蛋白和钩蛋白的合成在转录水平受到调控， 我们的目标之一是了解基因转录是如何 在时间上进行调节，以给出观察到的周期性表达模式 在细胞周期中。 该基因的核苷酸序列和基因结构 多顺反子钩操纵子将被确定，并且由多顺反子钩操纵子编码的多肽将被确定。 它将被识别。 转录的S1作图开始于 并且hook基因簇中的相邻转录单位将被 进行定位调节序列，并提供直接测定， 基因表达。 将对这些序列进行系统的突变分析。 进行鉴定启动子和5'调控区， 负责对钩子操纵子的周期性控制 提案 反式作用基因产物的遗传和生物化学分析， 还提供了hook和鞭毛蛋白基因表达所需的基因。 为了研究细胞包膜中空间定位的机制， 构建了一系列用于C.新月形细胞是 计划好了 蛋白质的极性定位将通过在 与探针基因如LacZ的C末端部分的体外基因融合， PhoA。 这种类型的实验将表明， 靶向极性蛋白包含在蛋白序列内。 免疫学方法将用于识别专门的膜 细胞极的蛋白质。

Caulobacter crescentus has a well defined life cycle in which a stalked cell divides repeatedly and asymmetrically to produce the stalked cell plus a new swarmer cell, which carries a constellation of surface structures, including one flagellum, pili, and a holdfast; all of these structures are assembled at the stalk distal pole at discrete times in the cell cycle. Flagellin and hook protein synthesis are regulated at the transcriptional level, and one of our goals is to understand how gene transcription is temporally regulated to give the observed patterns of periodic expression in the cell cycle. The nucleotide sequence and gene organization of the polycistronic hook operon will be determined and the polypeptides coded by it will be identified. S1 mapping of the transcriptional starts in this and the adjacent transcriptional units in the hook gene cluster will be carried out to locate regulatory sequence and to provide a direct assay for gene expression. A systematic mutational analysis of the sequences will be carried out to identify the promoters and the 5' regulatory regions that are responsible for periodic control of the hook operon. Proposals for a genetic and biochemical analysis of the trans-acting gene products that are required for hook and flagellin gene expression are also presented. To examine the mechanism of spatial localization in the cell envelope, the contruction of a series of fusion vectors for use in C. crescentus cells is planned. Polar localization of proteins will be examined by making in vitro gene fusions to the C-terminal portion of probe genes like LacZ and PhoA. This type of experiment will indicate whether the information for targeting polar proteins is contained within the protein sequence. Immunological approaches will be used to identify specialized membrane proteins at the cell pole.