SpoT(ppGpp)调控幽门螺杆菌适应抗生素压力分子机制研究

Prevalence of Helicobacter pylori(H pylori)resistance to antibiotics is becoming more and more serious, especially for metronidazole, amoxicillin and clarithromycin that is often used to cure H.pylori infection, which greatly influenced the recover rate, although the resistance genes to these three kinds of antibiotic has been basically determined, but the molecular regulation mechanism is still not clear. Studies suggest that stress response is the key factor that leads to bacterial drug resistance, not enough use of antibiotics (below the bactericidal concentration) can induce bacterial stress response. ppGpp is the key molecule to control bacterial stress response. In H.pylori genome ppGpp is synthesized by the SpoT, our preliminary experiments show SpoT was induced in H.pylori exposed to high concentration antibiotics, and the survivability of SpoT mutant strains was greatly reduced, which indicateds that SpoT involved in H.pylori drug resistance, but its molecular regulation mechanism is unclear, so we will compare gene expression differentiation between wild strains and the SpoT mutant strains，stimulated by high concentration antibiotics, application of cDNA microarray to analyse the molecular regulation mechanism of SpoT for H.pylori to adapt to the antibiotics, and screen and identify the key target genes involved in antibiotics resistance , our studies would provide clues for the rational use of antibiotics and give theoretical basis for the design of new antibiotics.

幽门螺杆菌耐药性日益严重，特别是对幽门螺杆菌感染"三联疗法"中常用的三种抗生素（甲硝唑、阿莫西林与克拉霉素），这大大影响了幽门螺杆菌感染的的治愈率，虽然这三种抗生素的耐药基因已经基本确定，但耐药产生之前，幽门螺杆菌如何适应抗生素压力而得以生存的调控机制却不明确。研究表明细菌的压力应答调控是其适应抗生素压力而得以生存最终产生耐药的关键因素。ppGpp是一个关键的压力调控分子，在幽门螺杆菌基因组中这个分子由基因SpoT合成，我们前期实验证明抗生素压力可以诱导幽门螺杆菌SpoT高表达，同时SpoT突变株在抗生素压力下生存力大大降低，这说明SpoT参与幽门螺杆菌适应抗生素压力，但分子机制不明，我们应用基因芯片技术比较抗生素刺激下野生株与SpoT突变株基因表达差异，分析SpoT 调控幽门螺杆菌适应抗生素压力的分子机制，筛选并验证关键靶基因，为抗生素合理使用以及新抗生素的设计提供理论基础。

幽门螺杆菌是导致胃癌的重要致病菌，目前幽门螺杆菌的耐药性日益严重，世界卫生组织将耐克拉霉素幽门螺杆菌定义为高危细菌，更为严重的是已经发现幽门螺杆菌多耐药菌株，形成生物膜也是导致幽门螺杆菌多耐药的重要原因之一，以上因素给临床幽门螺杆菌的有效治疗带来困难，因此有必要对幽门螺杆菌的耐药机制进行研究。研究表明细菌耐药性的产生来自于对抗生素压力逐步适应，压力调控分子细菌在细菌耐药性产生过程中具有重要作用。我们以压力调控分子SpoT为研究核心，分析SpoT调控幽门螺杆菌耐受克拉霉素，形成生物膜以及产生多耐药的分子机制。研究表明SpoT所调控的转运蛋白HP0939, HP1017, HP0497与HP0471对幽门螺杆菌适应克拉霉素至关重要；SpoT所调控的葡萄糖转运蛋白HP1174参与幽门螺杆菌生物膜形成与多耐药。关键耐药靶分子的发现为设计新的幽门螺杆菌抗菌药物提供了线索。