CONJUGAL TRANSFER OF BACTEROIDES ANTIBIOTIC RESISTANCES

描述（改编自申请人的摘要）：拟杆菌， 在人类结肠和女性中数量上占优势的细菌属 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 产生B的菌株。fragilis引起尿道感染，特别是 在艾滋病患者身上。 对两种药物的耐药性 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，并开始复杂化治疗 类杆菌感染。 现在几乎所有的临床分离株 对四环素耐药，而四环素耐药曾经是 少见.编码对四环素、克林霉素和 β-内酰胺类抗生素正被一个大家族 接合染色体元件（Tc\r元件）。 Tc\r元素不 不仅转移自身，还动员共存质粒， 切除，环化和转移较小的染色体元件， NBU。抗性基因通过这三条途径传播。 一个不寻常 Tc\r元件的特征是自身转移、质粒移动 和NBU切除受四环素刺激。这一特点提高了 关于四环素的广泛使用是否 非临床应用，如提高牲畜的饲料效率 动物的行为导致了耐药性的传播。四环素刺激 的转移是由两个转录激活因子，RteB和 RteC。 Tc\r元件通过一种机制位点特异性地整合， 不同于以往研究的任何整合机制。Tc\r元素 非常大（> 70 kbp）。为了方便他们的学习， 的元素将被构建。参与切除的基因和 元素的整合将被排序和表征， 将确定它们是否受RteB/RteC监管。的端部 元件和靶位点将被诱变以确定哪些碱基是 对融合和切割至关重要。携带基因的区域， 形成配合孔并启动循环转移的转移 中间体定位于15 kbp区域。转座子诱变 将被用于确定该区域的必需基因。这些基因 将由以下人员进行排序、表征和检查 RteB/RteC。 序列分析表明NBU整合和切除 这些元件可能与噬菌体λ类似地整合，但 可能是整合酶的基因的部分序列显示没有相似性 与λ整合酶家族成员有关。5 kbp的测序结果表明， NBU 1整合/切除区将被完成，并且该区域中的基因将被激活。 将确定切除和整合所必需的区域。 将确定RteB对这些基因的调控。的目的和 NBU 1靶位点将被诱变以确定 对融合和切割至关重要。

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.