Mitigation of Stress Responses By Protein Transfer Through Conjugation Machines

项目摘要 缀合系统因其在传播移动的遗传元件（MGE）和 在许多种细菌中，抗生素抗性、适应性和毒性基因的货物。的巨大 与MGE传播的抗生素耐药性相关的医学问题因以下事实而加剧： 接合系统也编码促进细胞间接触的表面粘附素或接合皮利 有利于传播和建立健壮的、抗真菌的生物膜群落。此外，委员会认为， 各种环境压力，包括抗生素，已被证明可以刺激MGE传播 相反，MGE转移诱导SOS反应并激活整合子的运动， 是抗生素抗性基因的储存库。除了接合可以影响的无数方式之外， 抗生素耐药性和基因组进化的发展，我们已经表明， 缀合诱导的SOS是受体细胞中突变的升高的积累。减轻 交配诱导突变的有害后果，这里称为MIM，许多接合元件携带 基因如psiB和ssb，其产物抑制SOS反应。在我们对F型质粒的研究中， pED 208，我们发现PsiB和SSB通过缀合通道，也称为 IV型分泌系统（T4 SS）。此外，易位的PsiB和SSB抑制了两种细胞的增殖。 接合子的SOS反应和MIM。ssb和psiB基因由维持/前导基因携带， F质粒和许多其他接合质粒的MLR区域，以及其他几个基因， 预期产物在转移至受体细胞后促进MGE的建立。 我们已经证明，pED 208 缀合转移至少9种MLR编码的蛋白质，以及7种染色体编码的蛋白质， 预测或已知的DNA代谢和缓解压力的功能。在目标1中，我们将定义函数 PsiB、SSB和第三种蛋白质PsiA在调节供体中的SOS反应和MIM中的相互作用， 在接合期间的受体细胞。我们还将评估PsiB和SSB的更广泛的生物学作用 易位通过研究其他模式接合系统和内部和种间交配，并通过 评估外源胁迫对MGE转移和PsiB/SSB缓解胁迫反应的影响， 突变在目标2中，我们将鉴定和表征其他易位的MLR蛋白的生物学功能 由F型质粒pED 208编码。我们将定义染色体编码的 转移蛋白质，并启动探索生物功能的研究，最初侧重于验证假设 交配诱导了氧化应激反应，而易位的SodA减轻了这种应激反应。 这些研究的结果将大大扩展我们对共轭系统如何有助于 细菌通讯、压力调节、抗生素抗性和基因组进化。

PROJECT SUMMARY Conjugation systems are widely known for their roles in disseminating mobile genetic elements (MGEs) and cargoes of antibiotic resistance, fitness, and virulence genes among many species of bacteria. The enormous medical problem associated with MGE-transmitted antibiotic resistance is enhanced by the fact that conjugation systems also code for surface adhesins or conjugative pili that promote intercellular contacts favoring transmission and establishment of robust, antibiotic-resistant biofilm communities. Furthermore, various environmental stresses, including antibiotics, have been shown to stimulate MGE transmission whereas, conversely, MGE transfer induces the SOS response and activates movement of integrons, which are reservoirs of antibiotic resistance genes. Adding to the myriad of ways conjugation can impact development of antibiotic resistance and genome evolution, we have shown that a consequence of conjugation-induced SOS is the elevated accumulation of mutations in recipient cells. To mitigate the deleterious consequences of mating-induced mutation, here termed MIM, many conjugative elements carry genes such as psiB and ssb whose products suppress the SOS response. In our studies of a model F plasmid, pED208, we discovered that PsiB and SSB are delivered through the conjugation channel, also known as a type IV secretion system (T4SS), to recipient cells. Furthermore, translocated PsiB and SSB suppress both the SOS response and MIM in transconjugants. ssb and psiB genes are carried by the maintenance/leading regions (MLRs) of F plasmids and many other conjugative plasmids, as are several other genes whose products are predicted to promote establishment of the MGE following transfer to recipient cells By use of a robust and quantitative Cre Recombinase Assay for Translocation (CRAfT), we have shown that pED208 conjugatively transfers at least 9 MLR-encoded proteins, as well as 7 chromosomally-encoded proteins with predicted or known functions in DNA metabolism and stress mitigation. In Aim 1, we will define the functional interplay of PsiB, SSB, and a third protein, PsiA, in modulating the SOS response and MIM in donor and recipient cells during conjugation. We will also evaluate the broader biological roles of PsiB and SSB translocation through studies of other model conjugation systems and intra- and interspecies matings, and by assessing effects of exogenous stresses on MGE transfer and PsiB/SSB mitigation of stress responses and mutation. In Aim 2, we will identify and characterize the biological functions of other translocated MLR proteins encoded by the model F plasmid, pED208. We will define the repertoire of chromosomally-encoded translocated proteins, and initiate studies exploring biological functions focusing initially on testing a hypothesis that mating induces the oxidative stress response and translocated SodA mitigates this stress response. Results of these studies will significantly expand our understanding of how conjugation systems contribute to bacterial communication, stress modulation, antibiotic resistance, and genome evolution.