Tse Man-Kit, Cheung Stanley K K, Ke Yi-hong, Lau Candy C Y, Sze Kong-Hung, Yuen Kwok-Yung
Department of Microbiology, The University of Hong Kong, Hong Kong SAR, China.
Biomol NMR Assign. 2014 Apr;8(1):173-6. doi: 10.1007/s12104-013-9477-3. Epub 2013 Apr 25.
Coxiella burnetii is an obligate intracellular gram-negative bacterium uniquely evolved to thrive in the inhospitable phagolysosome of macrophage. C. burnetii causes Q fever in humans and animals, which is emerging as a global public health concern. It is highly infectious and designated as a category B biowarfare agent because of its ubiquitous nature, abundant natural reservoirs, high resistance to environmental conditions, ease of transmission and low infectious dose. The lack of knowledge and awareness of C. burnetii leads to under-reporting and under-diagnosing of Q fever cases. Therefore, further understanding of the interactions between the infected host and the bacteria is necessary. C. burnetii macrophage infectivity potentiator (cb-Mip) is a secreted protein of 230 amino acids involving in intracellular survival of the pathogen. cb-Mip belongs to the family of FK506 binding protein, which possesses peptidyl-prolyl cis/trans isomerase (PPIase) activity. Besides acting as a PPIase, Mip protein homolog has been identified as virulence factor of many intracellular pathogenic microorganisms. In the present study, we report the near complete resonance assignments of the PPIase domain-containing region of Mip protein of C. burnetii. Secondary structure prediction based on chemical shift index analysis indicates that the protein adopts a predominately beta-strand structure, which is consistent with the crystal structure of homologous Mip protein in Legionella pneumophila.
伯氏考克斯氏体是一种专性细胞内革兰氏阴性细菌，其独特地进化为能在巨噬细胞恶劣的吞噬溶酶体中茁壮成长。伯氏考克斯氏体可导致人类和动物患Q热，这正成为一个全球公共卫生问题。它具有高度传染性，因其无处不在的性质、丰富的天然宿主、对环境条件的高抗性、易于传播和低感染剂量而被指定为B类生物战剂。对伯氏考克斯氏体的了解和认识不足导致Q热病例报告不足和诊断不足。因此，有必要进一步了解受感染宿主与细菌之间的相互作用。伯氏考克斯氏体巨噬细胞感染增强因子（cb-Mip）是一种由230个氨基酸组成的分泌蛋白，参与病原体的细胞内存活。cb-Mip属于FK506结合蛋白家族，具有肽基脯氨酰顺/反异构酶（PPIase）活性。除了作为一种PPIase发挥作用外，Mip蛋白同源物已被鉴定为许多细胞内致病微生物的毒力因子。在本研究中，我们报告了伯氏考克斯氏体Mip蛋白含PPIase结构域区域的近乎完整的共振归属。基于化学位移指数分析的二级结构预测表明，该蛋白主要采用β链结构，这与嗜肺军团菌中同源Mip蛋白的晶体结构一致。
