MECHANISMS OF SULFONAMIDE RESISTANCE IN E. COLI

大肠杆菌对磺酰胺的耐药机制

• 批准号: 3138457
• 负责人: BRIAN P NICHOLS
• 金额: $ 16.46万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1991-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3138457
• 关键词: Escherichia coli; antibiotics; autoradiography; bacterial DNA; enzyme inhibitors; folate; gel electrophoresis; gene expression; gene mutation; genetic manipulation; genetic mapping; genetic promoter element; membrane permeability; microorganism culture; microorganism genetics; microorganism growth; molecular cloning; natural gene amplification; nucleic acid hybridization; nucleic acid probes; nucleic acid sequence; p aminobenzoate; plasmids; pteridine analog; structural genes; sulfonamides; temperature sensitive mutant; thiazoles; transposon /insertion element

Sulfonamide antibiotics prevent the biosynthesis of reduced folate compounds by inhibiting the production of H2pteroate from 6-hydroxymethylpterin pyrophosphate and p- aminobenzaoate (PABA). A common mode of resistance to sulfonamide antibiotics in E. coli is via mutation of the structural gene encoding H2pteroate synthase, so that the altered enzyme product is a sulfonamide resistant form that discriminates more effectively between PABA and sulfonamides than does the wild type enzyme. Sulfonamide resistance conferred by many R-determinant plasmids isolated from multiple antibiotic resistant clinical E. coli strains is by the same mechanism: expression of a sulfonamide resistant H2pteroate synthase. However, I have shown that sulfonamide resistance in E. coli can be mediated by gene amplification. Although I have not yet determined the identity of the amplified gene, the gene encoding H2pteroate synthase is a prime candidate, since that gene product is the target of sulfonamide inhibition. The sulfonamide resistant strain that I am characterizing has an 8-fold tandemly amplified DNA segment 18 kb in length. The association of an insertion sequence (IS5) with one (or both) endpoints of the amplified DNA suggests a role for site specific (illegitimate) recombination. This event is distinct from other illegitimate amplifications that seem to be independent of IS sequences. This application proposes to determine the mechanism of the gene amplification event, and to characterize H2pteroate synthase structure, function and expression at the genetic level.

磺酰胺抗生素可预防降低的生物合成 叶酸化合物通过抑制H2Pteroate的产生 来自6-羟甲基甲基吡啶磷酸盐和P- Aminobenzaoate（PABA）。 对抵抗的常见方式 大肠杆菌中的磺酰胺抗生素是通过突变 编码H2PTEROATE合酶的结构基因，以便 改变的酶产物是一种抗磺酰胺的抗性形式 更有效地区分PABA和磺酰胺 比野生型酶。 磺酰胺耐药性 由从从中分离出来的许多R级质粒赋予 多种抗生素抗生素临床大肠杆菌菌株是 相同的机制：抗磺酰胺的表达 H2PTEROATE合酶。 但是，我已经证明了磺酰胺 大肠杆菌中的抗性可以通过基因扩增介导。 尽管我尚未确定放大的身份 基因，编码H2Pteroate合酶的基因是素数 候选人，因为该基因产物是磺酰胺的靶标 抑制。 我是磺胺胺的抗性菌株 表征具有8倍的串联放大DNA段 长度为18 kb。 插入序列的关联（IS5） 放大DNA的一个（或两个）端点表明 特定站点（非法）重组的作用。 这个事件是 与其他似乎是其他非法放大的区别 独立于IS序列。 此申请提出 确定基因扩增事件的机制，并确定 表征H2PTEROATE合酶结构，功能和 遗传水平的表达。