CARBON STARVATION GENE EXPRESSION IN ESCHERICHIA COLI

饥饿是细菌在大多数自然界中的常见经历 环境，包括病原体的宿主和这样的细菌 具有重要的应用价值。我们发现，不可区分的 大肠杆菌选择性地表达了几个时间 前3-5小时碳水化合物中独特蛋白质的种类 饿死了。这一现象产生了抗压细胞。 (饥饿、高温、氧化和渗透胁迫)。三节课 到目前为止已鉴定的这类基因有：cst基因--仅诱导 在碳饥饿和需要循环AMP/CRP的情况下；CSI 基因--也是由碳饥饿单独诱导的，但不依赖于 CAMP；和Pex基因--不依赖于cAMP/CRP，也由 饥饿缺乏碳以外的营养物质。人类的基因 后一类课程似乎对压力的形成负责 抵抗，但所有阶级的诱导可能取决于 指数后阶段所特有的转录系统。至 探索这个转录系统，我们将克隆并测序一个 Cst和csi基因，以及两个pex基因。用于克隆 启动子和非必需基因的启动子近端区域， 染色体(BLA)LacZ融合和缺陷质粒编码的BLA 将使用基因重组；衍生杂交探针 这将被用来克隆结构基因。对于 基本基因替代方法，如微测序 从2-D PAGE中分离的蛋白质将被使用。使用克隆的 基因，饥饿基因剂量对生存的影响将是 调查过了。适当的融合也将用于识别 碳饥饿的顺式和反式调节成分 正规药。

Starvation is a common experience of bacteria in most natural environments, including the hosts of pathogens, and such bacteria have applied importance. We have found that the nondifferentiating bacterium Escherichia coli selectively expresses several temporal classes of unique proteins in the first 3-5 hours of carbon starvation. This phenomenon generates stress-resistant cells (starvation, heat, oxidative and osmotic stresses). Three classes of such genes so far identified are: the cst genes--induced only under carbon starvation and requiring cyclic AMP/CRP; the csi genes--also induced by carbon starvation alone but independent of cAMp; and the pex genes--cAMP/CRP-independent and also induced by starvation for nutrients other than carbon. The genes of the latter classes appear responsible for the development of stress resistance, but the induction of all classes may depend on transcriptional systems unique to the postexponential phase. To explore this transcriptional system, we will clone and sequence one each of cst and csi genes, and two pex genes. For cloning the promoter and promoter-proximal regions of the nonessential genes, chromosomal (bla)lacZ fusions and defective plasmid-encoded bla gene reconstitution will be used; hybridization probes derived therefrom will be used in cloning the structural genes. For the essential genes alternate approaches, such as microsequencing of proteins isolated from 2-D PAGE, will be used. Using the cloned genes, the starvation gene dosage effect on survival will be investigated. Appropriate fusions will also be used to identify cis and trans acting regulatory components of the carbon starvation regulon.