铜绿假单胞菌 AmpG 的构结构特点及其转运功能分析

β-Lactam antibiotics is the most commonly used antibiotics in clinic. The bacteria’s resistance to this kind of antibiotics is becoming more and more serious. The medicine is facing challenges of treatment failure and infection recurrence which seriously threaten the health of the human beings. In this work, we will investigate the diversity of ampG genes from different species of the Pseudomonas aeruginosa and find out its relationship to bacteria’s resistance against β-lactam antibiotics and the cellular β-lactamase level. It reveals the efficiency of ampGs of different genotypes to transport glycopeptides which regulate the expression of the ampC gene. Three secondary structure of AmpG are predicted by homology modeling method.Through Multiple Sequence Alignment analysis the conservative domains of AmpG are predicted and by using site-directed mutagenesis and genetic complementation experiments the functional domains of AmpG will be identified. It will provide the screening or synthesizing inhibitory compound of ampG transporter with experimental data. Studies on the relationship between the structure and function of the trans-membrane transporter will play an important role in exploring a promising inhibitory compound on trans-membrane transporter. It also has theoretical significance and sheds light on the successful treatment against bacterial infections.

β-内酰胺类抗生素是临床上应用最广的抗生素，伴随着它在临床的应用，细菌对该类药物的耐药性日趋严重，治疗失败和感染复发是临床治疗面临的难点，感染性疾病严重影响着人类的生命健康。本课题通过研究临床不同时期铜绿假单胞的ampG 基因的多态性及其与致病菌对β-内酰胺类抗生素的耐药性、细胞内β-内酰胺酶水平的关系，揭示不同ampG 基因型编码产物转运糖肽的效率和对ampC基因的调控作用；通过多序列比对分析ampG 基因的保守功能域，同源建模法预测AmpG 的三级结构，结合定点突变和遗传互补实验对AmpG 的功能域进行鉴定，为下一步筛选或合成抑制ampG 转运蛋白功能的药物提供实验依据。研究细胞膜转运蛋白结构与功能的关系，为探寻有应用前景的抑制跨膜转运蛋白功能的药物打下实验基础，对于细菌性感染的治疗具有重要的理论意义。

β-内酰胺类抗生素是临床上应用最广的抗生素，伴随着它在临床的应用，细菌对该类药物的耐药性日趋严重，治疗失败和感染复发是临床治疗面临的难点，感染性疾病严重影响着人类的生命健康。ampG 编码一种膜结合转运蛋白，与 AmpC酶的表达有着密切联系。本课题通过提取临床不同时期具有代表性的铜绿假单胞菌的基因组进行ampG基因的测序并克隆，发现存在明显的多态性；利用生物信息技术分析了不同来源ampG基因的同源性及ampG基因的保守性，不同来源的ampG虽然整体的同源性较低，所含的跨膜区数目不尽相同，但其局部区域的氨基酸序列却相对保守；同源建模法预测了AmpG的三级结构，结合定点突变和遗传互补实验对AmpG的功能域进行鉴定，结果显示保守位点G29、I53、A129和A197的改变影响AmpG的功能。研究细胞膜转运蛋白结构与功能的关系，为探寻有应用前景的抑制跨膜转运蛋白功能的药物打下实验基础，对于细菌性感染的治疗具有重要的理论意义。