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肺炎克雷伯菌是一种常见的院内条件致病菌,通常定植在人体的呼吸道和胃肠道。但肺炎克雷伯菌是怎样在胃液的强酸条件下存活并进入肠道尚不十分清楚。本研究发现,酸性条件能够诱导肺炎克雷伯菌Kp Hde A基因表达上调。克隆Kp Hde A基因并将其转化大肠杆菌,获得可溶性的Kp Hde A蛋白并利用镍离子亲和层析纯化得到目的蛋白。光散射分析证明,酸性胁迫下,Kp Hde A蛋白能够减少酸诱导的醇脱氢酶聚集。荧光实验证明,酸胁迫可以诱导Kp Hde A蛋白的疏水基团暴露。圆二色谱实验证明,酸性条件能够诱导Kp Hde A蛋白形成无序结构。此外Kp Hde A蛋白的表达能提高大肠杆菌的耐酸能力。故推测,Kp Hde A蛋白具有分子伴侣活性,并在肺炎克雷伯菌抵抗酸胁迫中起重要作用。
Klebsiella pneumoniae is a common nosocomial pathogenic bacteria, usually colonized in the human respiratory and gastrointestinal tract. However, it is not yet clear how Klebsiella pneumoniae survives in the acid state of gastric juice and enters the gut. This study found that acidic conditions can induce Klebsiella pneumoniae Kp Hde A gene expression increased. The Kp Hde A gene was cloned and transformed into Escherichia coli to obtain soluble Kp Hde A protein. The target protein was purified by nickel ion affinity chromatography. Light scattering analysis demonstrated that Kp Hde A protein can reduce acid-induced aggregation of alcohol dehydrogenase under acid stress. Fluorescence experiments show that acid stress can induce the hydrophobic group of Kp Hde A protein to be exposed. Circular dichroism experiments show that acidic conditions can induce the Kp Hde A protein to form a disordered structure. In addition, the expression of Kp Hde A protein can improve the acid resistance of E. coli. Therefore, it is speculated that Kp Hde A protein has molecular chaperone activity and plays an important role in the resistance to acid stress of Klebsiella pneumoniae.