MULTICOPY SUPPRESSION OF AN ILV MUTATION IN E COLI K 12

肠致病性大肠杆菌菌株越来越重要 许多妇科疾病的病原体。 因为它被认为是 微生物的肠道细菌，继续寻求了解 它的基因组成和细胞功能至关重要。 在这 建议，PI试图解开乙酰羟基酸的表达 合成酶（AHAS）基因作为克隆到正常拷贝的结果 质粒 表达的“新的”AHAD活性对正常的 当克隆到高拷贝质粒pBR 322中时， 高 在几种细菌系统中已经报道了复制现象，但没有 在K-12的AHAS系统中。 具体目标包括：1）物理化学 表征从克隆片段得到的酶活性， 2)确定其它ILV基因对这种表达的影响 活性，3）确定新表达基因的拷贝数 染色体上，4）绘制相关基因，5）确定和 分析该基因的DNA序列。 了解基因的机制 在某些环境条件下的活化当然有助于 了解一些曾经被认为是 不致病。 参与该项目的学生将获得 在进行最先进的研究和 在研究中收集、分析和展示科学数据 会议和全国性会议。 所使用的技术可应用于 任何数量的领域，在双分子科学可能感兴趣的， 规划科学职业的学生。

Enteropathogenic strains of Escherichia coli are increasingly important agents of many diarrheal diseases. Because it is considered a prototype organism for enteric bacteria, continuing the search for understanding of its genetic make up and cellular functions is crucial. In this proposal, the PI seeks to unravel the expression of an acetohydroxy acid synthase (AHAS) gene as a consequence of cloning it into normal copy plasmid. The "new" AHAD activity expressed is refractory to normal inhibition by valine when cloned into a high copy plasmid, pBR322. High copy phenomena have been reported in several bacterial systems, but not in the AHAS system of K-12. Specific goals involve: 1) physicochemically characterizing the resulting enzymatic activity from the cloned fragment, 2) determining the effect of other ilv genes on expression of this activity, 3) determining the number of copies of the newly expressed gene on the chromosome, 4) mapping the genes involved and 5) determining and analyzing the DNA sequence of the gene. Understanding mechanisms of gene activation under certain environmental conditions certainly facilitate understanding the recent pathogenicity of some organisms once thought to be non-pathogenic. Students involved in this project will gain an invaluable experience in conducting state-of-the-art research and in collecting, analyzing and presenting scientific data at research conferences and national meetings. Technologies used may be applied to any number of areas in the bimolecular sciences which may interest the student in planning science careers.