青霉素结合蛋白3编码基因ftsI在多重耐药鲍曼不动杆菌中表达及碳青霉烯类诱导对其表达的影响

Expression of Penicillinbinding Protein 3 Encoding Gene FtsI in Multidrug-resistant Acinetobacter Baumannii and the Effect of Carbapenems Induction on Its Expression

目的研究青霉素结合蛋白3(penicillin-binding protein 3,PBP3)编码基因ftsI在多重耐药鲍曼不动杆菌(Multidrug resistant Acinetobacter baumannii,MDR-AB)中表达情况,探明碳氢霉烯诱导对MDR-AB中ftsI表达的影响。方法收集2019年1月~6月成都市郫都区人民医院临床分离的38株MDR-AB菌株,PCR扩增ftsI基因,产物进行测序,将MDR-AB菌株与鲍曼不动杆菌敏感株(SDF)ftsI基因序列翻译成氨基酸序列进行同源建模和可视化比对分析。然后再分别用亚胺培南、美罗培南和多尼培南对菌株进行诱导,qRT-PCR检测ftsI的表达情况。结果38株MDR-AB均携带ftsI基因,测序结果与Genbank中ATCC 17978标准菌株ftsI序列显示99.54%同源,将菌株MDR-AB 1与SDF株的ftsI基因序列翻译成氨基酸序列后,发现SDF菌株多出251号位赖氨酸、252号位苏氨酸、253号位甘氨酸和254号位缬氨酸,同源建模和可视化分析发现两者ftsI基因编码蛋白空间结构明显不同。MDR-AB菌株经三种碳氢霉烯类抗生素诱导后,ftsI基因相对表达量均下降,其中亚胺培南组和美罗培南组相对于未处理组ftsI基因表达下调差异有统计学意义(t=5.314,5.424,均P<0.05)。结论MDR-AB普遍携带ftsI基因,其ftsI编码蛋白空间结构与SDF菌株存在明显差异,这可能是AB产生耐药的一个重要因素。碳氢霉烯类诱导可导致ftsI基因表达下调,以亚胺培南、美罗培南诱导效果最明显。

Objective To investigate the gene ftsI encoding penicillin binding protein 3(PBP3)in Multi drug resistant Acinetobacter baumannii(MDRAB),and observe the expression of ftsI in MDR-AB and the effect of carbasolene induction on the expression of ftsI.Methods The 38 strains of MDR-AB isolated from Pidu District People’s Hospital of Chengdu from January to June 2019,and ftsI gene was amplified by PCR and the products were sequenced and analyzed.The ftsI gene sequences of MDR-AB strain and Acinetobacter baumannii sensitive strain(SDF)were translated into amino acid sequences for homology modeling and visual comparison.Then,the strains were induced with Imipenem,Meropenem and Donipenem,and the expression of ftsI was detected by qRT-PCR.Results All the 38 strains of MDR-AB carried ftsI gene,and the sequencing results showed 99.54%homology with the ftsI sequence of ATCC 17978 standard strain in GenBank.After translating the ftsI gene sequences of MDR-AB 1 and SDF strains into amino acid sequences,it was found that SDF strains had more Lys251,Thr252,Gly253 and Val254.Homology modeling and visualization analysis showed that the spatial structure of the proteins encoded by ftsI gene was significantly different between the two strains.The relative expression of ftsI gene in the MDR-AB strain was decreased after induction by three kinds of carbasenes,and the Imipenem group and Meropenem group was statistically different from that in the untreated group(P<0.05).Conclusion MDR-AB generally carries ftsI gene,and the spatial structure of ftsI encoding protein was significantly different from that of SDF strain,this may be an important factor in the resistance of AB.Carbonasene induction can lead to the down-regulation of ftsI gene expression,and the induction of Imipenem and Meropenem is most obvious.