Total, Membrane, and Immunogenic Proteomes of Macrophage- and Tick Cell-Derived Ehrlichia chaffeensis Evaluated by Liquid Chromatography-Tandem Mass Spectrometry and MALDI-TOF Methods

Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506, USA.
Infection and immunity (Impact Factor: 3.73). 09/2008; 76(11):4823-32. DOI: 10.1128/IAI.00484-08
Source: PubMed


Ehrlichia chaffeensis, a tick-transmitted rickettsial, is the causative agent of human monocytic ehrlichiosis. To examine protein expression patterns, we analyzed total, membrane, and immunogenic proteomes of E. chaffeensis originating from macrophage and tick cell cultures. Total proteins resolved by one-dimensional gel electrophoresis and subjected to liquid chromatography-electrospray ionization ion trap mass spectrometry allowed identification of 134 and 116 proteins from macrophage- and tick cell-derived E. chaffeensis, respectively. Because a majority of immunogenic proteins remained in the membrane fraction, individually picked total and immunogenic membrane proteins were also surveyed by liquid chromatography-tandem mass spectrometry and matrix-assisted laser desorption ionization-time of flight methods. The analysis aided the identification of 48 additional proteins. In all, 278 genes of the E. chaffeensis genome were verified as functional genes. They included genes for DNA and protein metabolism, energy metabolism and transport, membrane proteins, hypothetical proteins, and many novel proteins of unknown function. The data reported in this study suggest that the membrane of E. chaffeensis is very complex, having many expressed proteins. This study represents the first and the most comprehensive analysis of E. chaffeensis-expressed proteins. This also is the first study confirming the expression of nearly one-fourth of all predicted genes of the E. chaffeensis genome, validating that they are functionally active genes, and demonstrating that classic shotgun proteomic approaches are feasible for tick-transmitted intraphagosomal bacteria. The identity of novel expressed proteins reported in this study, including the large selection of membrane and immunogenic proteins, will be valuable in elucidating pathogenic mechanisms and developing effective prevention and control methods.

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Available from: Roman Reddy Ganta, Aug 21, 2014
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    • "An alternative approach of dissecting rickettsial virulence is to examine the presence of differentially produced rickettsial proteins during infection. While proteomic and immunoreactive profiles have been described for several rickettsial species (Chao et al., 2004, 2007; Hajem et al., 2009; Ogawa et al., 2007; Pornwiroon et al., 2009; Renesto et al., 2005; Sears et al., 2012; Tucker et al., 2011) and closely related tick-borne bacterial pathogens such as Anaplasma (Lopez et al., 2005) and Ehrlichia (Seo et al., 2008), little has been done with comparative antigenic analysis of different rickettsial species. In this study, a comparative immunoproteomic approach using sera from R. parkeri-infected patients was employed for the identification and distinction of several immunoreactive proteins from R. parkeri and R. amblyommii. "
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    • "July 2014 | Volume 4 | Article 86 | 4 encodes for superoxide dismutase) infecting mammalian cells as compared with infected vector cells (Kuriakose et al., 2011) and for A. phagocytophilum (APH_0795 encodes for antioxidant AhpC/Tsa family) (Nelson et al., 2008). Superoxide dismutase was also detected in the global proteome of E. chaffeensis (Seo et al., 2008). In E. ruminantium proteome, TsaA and ElbB proteins, both involved in cell redox homeostasis, were detected. "
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