CONJUGAL TRANSFER OF BACTEROIDES ANTIBIOTIC RESISTANCES

拟杆菌抗生素耐药性的夫妻传播

• 批准号: 2671825
• 负责人: Abigail A Salyers
• 金额: $ 22.24万
• 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/2671825
• 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(改编自申请者摘要)：拟杆菌属 人体和女性结肠中细菌的数量优势属 阴道炎，也是引起内脓肿和 结肠癌或腹部创伤患者的菌血症。肠毒素 产生脆弱芽孢杆菌的菌株会引起腹泻感染，尤其是 在艾滋病患者身上。对两种首选药物的耐药性 治疗类杆菌感染、克林霉素和β-内酰胺类抗生素 已经开始出现，并开始使治疗变得复杂 类杆菌感染。几乎所有的临床分离株现在都是 对四环素耐药，而四环素耐药性曾经 不同寻常。编码四环素、克林霉素和 β-内酰胺类抗生素是由一个大型家庭转移的 结合的染色体元素(TC\r元素)。TC\r元素备注 不仅转移自身，而且还动员共存的质粒和 切除、循环和转移较小的染色体元件 NBU。抗性基因正通过这三条途径传播。一种不同寻常的 T_c\r元件的特点是自我转移、质粒动员 和NBU切除受四环素刺激。此功能会引发 关于四环素的广泛使用是否会导致 提高家畜饲料效率等非临床应用 动物的病正在助长耐药性的传播。四环素刺激性 的转移是由两个转录激活子，RteB和 RTEC。Tcr元素通过一种机制结合在一起 不同于之前研究的任何整合机制。T_c\r元素 都相当大(&gt；70kBP)。为了方便他们的学习，一个微型表格 的元素将被构造。参与切除和切除的基因 元素的集成将被排序和表征，并且它 将确定它们是否受RteB/RTEC的监管。的末尾 分子和靶点将被诱变以确定碱基是什么 对于整合和切除来说是必不可少的。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15KBP区域。转座子诱变 将被用来识别该区域的必需基因。这些基因 将由以下机构进行排序、表征和检查以进行监管 RteB/RTEC。NBU整合和切除的序列分析表明 这些元素的整合可能类似于噬菌体lambda，但 可能是整合酶的基因的部分序列没有相似性 到lambda整合酶家族的成员。5 kbp的测序 NBU1整合/切除区域将完成，其中的基因 将确定对切除和整合至关重要的区域。 RteB对这些基因的调控将被确定。两端和 将对NBU1的靶点进行突变，以确定哪些碱基 对于整合和切除来说是必不可少的。