Lin Mingqun, Kikuchi Takane, Brewer Heather M, Norbeck Angela D, Rikihisa Yasuko
Department of Veterinary Biosciences, The Ohio State University Columbus, OH, USA.
Front Microbiol. 2011 Feb 17;2:24. doi: 10.3389/fmicb.2011.00024. eCollection 2011.
Anaplasma phagocytophilum and Ehrlichia chaffeensis are obligatory intracellular α-proteobacteria that infect human leukocytes and cause potentially fatal emerging zoonoses. In the present study, we determined global protein expression profiles of these bacteria cultured in the human promyelocytic leukemia cell line, HL-60. Mass spectrometric (MS) analyses identified a total of 1,212 A. phagocytophilum and 1,021 E. chaffeensis proteins, representing 89.3 and 92.3% of the predicted bacterial proteomes, respectively. Nearly all bacterial proteins (≥99%) with known functions were expressed, whereas only approximately 80% of "hypothetical" proteins were detected in infected human cells. Quantitative MS/MS analyses indicated that highly expressed proteins in both bacteria included chaperones, enzymes involved in biosynthesis and metabolism, and outer membrane proteins, such as A. phagocytophilum P44 and E. chaffeensis P28/OMP-1. Among 113 A. phagocytophilum p44 paralogous genes, 110 of them were expressed and 88 of them were encoded by pseudogenes. In addition, bacterial infection of HL-60 cells up-regulated the expression of human proteins involved mostly in cytoskeleton components, vesicular trafficking, cell signaling, and energy metabolism, but down-regulated some pattern recognition receptors involved in innate immunity. Our proteomics data represent a comprehensive analysis of A. phagocytophilum and E. chaffeensis proteomes, and provide a quantitative view of human host protein expression profiles regulated by bacterial infection. The availability of these proteomic data will provide new insights into biology and pathogenesis of these obligatory intracellular pathogens.
嗜吞噬细胞无形体和恰菲埃立克体是专性细胞内α-变形菌，可感染人类白细胞并引起具有潜在致命性的新发人畜共患病。在本研究中，我们测定了在人早幼粒细胞白血病细胞系HL-60中培养的这些细菌的整体蛋白质表达谱。质谱（MS）分析共鉴定出1212种嗜吞噬细胞无形体蛋白和1021种恰菲埃立克体蛋白，分别占预测细菌蛋白质组的89.3%和92.3%。几乎所有具有已知功能的细菌蛋白（≥99%）都有表达，而在感染的人类细胞中仅检测到约80%的“假定”蛋白。定量MS/MS分析表明，两种细菌中高表达的蛋白包括伴侣蛋白、参与生物合成和代谢的酶以及外膜蛋白，如嗜吞噬细胞无形体的P44和恰菲埃立克体的P28/OMP-1。在113个嗜吞噬细胞无形体p44旁系同源基因中，有110个表达，其中88个由假基因编码。此外，HL-60细胞的细菌感染上调了主要参与细胞骨架成分、囊泡运输、细胞信号传导和能量代谢的人类蛋白的表达，但下调了一些参与固有免疫的模式识别受体。我们的蛋白质组学数据代表了对嗜吞噬细胞无形体和恰菲埃立克体蛋白质组的全面分析，并提供了受细菌感染调节的人类宿主蛋白表达谱的定量视图。这些蛋白质组学数据的可用性将为这些专性细胞内病原体的生物学和发病机制提供新的见解。
