Kuczynska-Wisnik Dorota, Cheng Chuanmin, Ganta Roman R, Zolkiewski Michal
Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA.
Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA.
FEMS Microbiol Lett. 2017 Mar 1;364(6). doi: 10.1093/femsle/fnx059.
Ehrlichia chaffeensis is an obligatory intracellular pathogen transmitted through infected ticks to humans and other vertebrates. We investigated the extent of protein aggregation in E. chaffeensis during infection of canine macrophage cell line, DH82. We discovered that the size of the aggregated fraction of E. chaffeensis proteins increased during the first 48 h post infection. We also incubated the infected cells with guanidinium chloride (GuHCl), a known inhibitor of the protein-disaggregating molecular chaperone ClpB. Up to 0.5 mM GuHCl had no impact on the host cells, whereas the viability of the pathogen was reduced by ∼60% in the presence of the inhibitor. Furthermore, we found that the size of the aggregated protein fraction in E. chaffeensis increased significantly in cultures supplemented with 0.5 mM GuHCl, which also resulted in the preferential accumulation of ClpB with the aggregated proteins. Altogether, our results suggest that an exposure of E. chaffeensis to the stressful environment of a host cell results in an increased aggregation of the pathogen's proteins, which is exacerbated upon inhibition of ClpB. Our studies establish a link between protein quality control and pathogen survival during infection of a host.
查菲埃立克体是一种专性细胞内病原体，通过感染的蜱传播给人类和其他脊椎动物。我们研究了在犬巨噬细胞系DH82感染过程中查菲埃立克体中蛋白质聚集的程度。我们发现，感染后最初48小时内，查菲埃立克体蛋白质聚集部分的大小增加。我们还用已知的蛋白质解聚分子伴侣ClpB的抑制剂氯化胍（GuHCl）孵育感染的细胞。高达0.5 mM的GuHCl对宿主细胞没有影响，而在抑制剂存在的情况下，病原体的活力降低了约60%。此外，我们发现，在补充了0.5 mM GuHCl的培养物中，查菲埃立克体中聚集蛋白部分的大小显著增加，这也导致ClpB与聚集蛋白优先积累。总之，我们的结果表明，查菲埃立克体暴露于宿主细胞的应激环境会导致病原体蛋白质聚集增加，而在ClpB受到抑制时这种情况会加剧。我们的研究建立了宿主感染期间蛋白质质量控制与病原体存活之间的联系。
