表皮葡萄球菌新的生物膜调控因子丝氨酸、苏氨酸蛋白激酶stk基因的功能研究

发布时间：2017-12-28 21:16

本文关键词：表皮葡萄球菌新的生物膜调控因子丝氨酸、苏氨酸蛋白激酶stk基因的功能研究　出处：《复旦大学》2010年硕士论文　论文类型：学位论文

【摘要】： 表皮葡萄球菌是引起院内感染的主要致病菌之一,其致病性主要为在植入性医疗器材表面形成生物膜。生物膜是细菌黏附于有机或无机材料表面,合成分泌细胞外基质包被细菌所形成的细菌群体结构。生物膜的形成是细菌逃逸宿主免疫清除的主要机制,也是细菌体内播散感染的病灶。因此,对于表皮葡萄球菌生物膜形成分子机制的深入研究,将有助于提供防治表皮葡萄球菌感染的有效措施。以往报道丝氨酸／苏氨酸蛋白激酶(Serine/Threoine protein Kinase, stk)基因对生物膜形成发挥作用,为了研究其在表皮葡萄球菌中的功能,我们构建了一株表皮葡萄球菌stk变菌株。与野生菌株相比,stk变菌株生物膜形成能力显著下降。我们将表皮葡萄球菌stk基因克隆到质粒上,然后转化入stk变菌株,得到的基因互补菌株生物膜形成能力回复到野生菌株的水平。这些结果表明表皮葡萄球菌生物膜形成需要stk的功能。与野生菌株相比,stk变菌株对高分子材料的粘附能力显著下降,细胞间粘附因子PIA的合成量减少,生物膜相关调控因子ica操纵子转录水平降低,这三个表型变化可能是突变菌株生物膜形成能力下降的原因。与野生菌株相比,stk变菌株细胞壁结构发生变化,在基本培养基中生长减慢,这些研究结果表明表皮葡萄球菌新陈代谢和细胞壁合成均需要Stk蛋白的功能。我们用小鼠皮下插管感染模型比较stk突变菌株与野生菌株引起插管相关感染的致病能力,结果显示stk突变菌株较不容易引起插管相关感染,这表明其功能有助表皮葡萄球菌引起插管相关感染。本研究揭示表皮葡萄球菌stk基因是其生物膜形成及毒力的重要的调控基因,并且可能通过控制ica基因的表达方式调控生物膜。我们也发现了表皮葡萄球菌stk基因可影响细胞壁合成和新陈代谢。另外,本文中对stk基因的研究提示它们可能作为潜在的药物靶标用于防治表皮葡萄球菌感染。
[Abstract]:Staphylococcus epidermidis is one of the main pathogens causing nosocomial infection. The pathogenicity of Staphylococcus epidermidis is mainly the formation of biofilm on the surface of implant medical equipment. Biofilms are bacteria group structures formed by bacteria on the surface of bacteria that adhere to organic or inorganic materials to synthesize and secrete the extracellular matrix of bacteria. The formation of biomembrane is the main mechanism of the immune clearance of the host escaping from the host, and it is also the focus of infection in the bacteria. Therefore, the in-depth study of the molecular mechanism of the biofilm formation of Staphylococcus epidermidis will help to provide effective measures for the prevention and control of Staphylococcus epidermidis infection. It has been reported that Serine/Threoine protein Kinase (STK) gene plays a role in biofilm formation. In order to study its function in Staphylococcus epidermidis, we constructed a strain of Staphylococcus epidermidis STK strain. Compared with the wild strains, the biofilm formation ability of STK strain decreased significantly. We cloned Staphylococcus epidermidis STK gene into plasmid and transformed into STK strain. The gene complementary bacteria biofilm formation ability returned to the level of wild strain. These results suggest that the biofilm formation of Staphylococcus epidermidis requires STK function. Compared with the wild strain, STK strain on the adhesion ability of polymer materials significantly decreased synthesis of intercellular adhesion molecule-1 PIA reduced biofilm associated factors of ica operon transcription level decreased, the three phenotypic changes may be the reason mutants of biofilm formation ability decreased. Compared with the wild strain, the cell wall structure of STK strain changed, and its growth slowed down in the basic medium. These results indicate that the Stk protein function is needed for the metabolism and cell wall synthesis of Staphylococcus epidermidis. We compared the pathogenicity of STK mutant strains and wild strains to cannulation related infection by using a mouse subcutaneous intubation infection model. The results showed that STK mutant strains were less likely to cause intubation related infections, suggesting that their functions could help Staphylococcus epidermidis infection related to intubation.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R378.11

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