CONJUGAL TRANSFER OF BACTEROIDES ANTIBIOTIC RESISTANCES

拟杆菌抗生素耐药性的夫妻传播

• 批准号: 2390287
• 负责人: Abigail A Salyers
• 金额: $ 21.4万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-30 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2390287
• 关键词: Bacteroides; Escherichia coli; bacterial genetics; bacteriophage lambda; chromosome deletion; drug resistance; fusion gene; gene expression; genetic mapping; genetic regulatory element; integrase; microorganism conjugation; molecular cloning; nucleic acid sequence; tetracyclines; transfection; transposon /insertion element

DESCRIPTION (Adapted from applicant's abstract): Bacteroides, one of the numerically predominant genera of bacteria in the human colon and female vaginal tract, is also a common cause of internal abscesses and bacteremia in people with colon cancer or abdominal trauma. Enterotoxin producing strains of B. fragilis cause diarrheal infections,especially in people with AIDS. Resistance to two of the drugs of choice for treating Bacteroides infections, clindamycin and beta-lactam antibiotics has begun to appear and is beginning to complicate treatment of Bacteroides infections. Virtually all clinical isolates are now resistant to tetracycline whereas tetracycline resistance was once uncommon. The genes encoding resistance to tetracycline, clindamycin and beta-lactam antibiotics are being transferred by a family of large conjugative chromosomal elements (Tc\r elements). Tc\r elements not only transfer themselves but also mobilize co-resident plasmids and excise, circularize and transfer smaller chromosomal elements called NBUs. Resistance genes are being spread by all three routes. An unusual feature of the Tc\r elements is that self-transfer, plasmid mobilization and NBU excision are stimulated by tetracycline. This feature raises questions about whether the widespread use of tetracycline for nonclinical applications like increasing feed efficiency of livestock animal's is contributing to resistance spread. Tetracycline stimulation of transfer is mediated by two transcriptional activators, RteB and RteC. The Tc\r elements integrate site-specifically by a mechanism that is unlike any previously studied integration mechanism. The Tc\r elements are quite large (> 70 kbp). To facilitate their study, a miniature form of the element will be constructed. The genes involved in excision and integration of the element will be sequenced and characterized and it will be determined if they are regulated by RteB/RteC. The ends of the element and target site will be mutagenized to determine what bases are essential for integration and excision. The region carrying genes that form the mating pore and initiate transfer of the circular transfer intermediate have been located in 15 kbp region. Transposon mutagenesis will be used to identify essential genes in this region. These genes will be sequenced, characterized and checked for regulation by RteB/RteC. Sequence analysis of NBU integratIon and excision indicated that these elements might integrate similarly to phage lambda, but the partial sequence of a gene that may be the integrase shows no similarity to members' of the lambda integrase family. The sequencing of the 5 kbp NBU1 integration/excision region will be completed, and genes in this region essential for excision and integration will be identified. Regulation of these genes by RteB will be determined. The ends and target site of NBU1 will be mutagenized to determine what bases are essential for integration and excision.

描述（改编自申请人的摘要）：拟杆菌属，细菌之一 人类结肠和女性结肠中数量占优势的细菌属 阴道，也是内部脓肿的常见原因 结肠癌或腹部创伤患者的菌血症。肠毒素 脆弱拟杆菌的产生菌株会引起腹泻感染，尤其是 艾滋病患者。 对两种选择的药物产生耐药性 治疗拟杆菌感染，克林霉素和 β-内酰胺抗生素 已经开始出现并且开始使治疗变得复杂 拟杆菌感染。 现在几乎所有临床分离株 对四环素耐药，而四环素耐药曾经 罕见。编码四环素、克林霉素和抗性的基因 β-内酰胺抗生素正在由一个大家族进行转移 接合染色体元件（Tc\r 元件）。 Tc\r 元素不 不仅可以转移自身，还可以动员共存质粒 切除、环化和转移较小的染色体元件，称为 NBU。抗性基因正在通过所有三种途径传播。 一个不寻常的 Tc\r元件的特点是自我转移、质粒动员 四环素刺激 NBU 切除。这个功能提高了 关于四环素是否广泛使用的问题 非临床应用，例如提高牲畜的饲料效率 动物的病毒正在促进耐药性的传播。四环素刺激 转移是由两种转录激活因子 RteB 和 RteC。 Tc\r 元素通过一种机制进行特定于位点的集成： 与之前研究的任何整合机制不同。 Tc\r 元素 相当大（> 70 kbp）。为了方便他们的学习，制作了一个微型表格 将构造该元素的。参与切除和切除的基因 元素的整合将被排序和表征，并且它 将确定它们是否受 RteB/RteC 监管。的两端 元素和目标位点将被诱变以确定碱基是什么 对于整合和切除至关重要。携带基因的区域 形成配合孔并启动圆形转移的转移 中间体位于 15 kbp 区域。转座子诱变 将用于识别该区域的必需基因。这些基因 将被排序、表征和检查监管 RteB/RteC。 NBU 整合和切除的序列分析表明 这些元素可能与 lambda 噬菌体类似地整合，但是 可能是整合酶的基因的部分序列显示没有相似性 λ 整合酶家族的成员。 5 kbp 的测序 NBU1整合/切除区域将完成，该区域的基因 将确定切除和整合所必需的区域。 RteB 对这些基因的调节将被确定。结束和 NBU1 的目标位点将被诱变以确定哪些碱基 对于整合和切除至关重要。