News and Publications - Research Highlight
First use of global proteomics to quantify bacterial proteins isolated from host cells
PNNL scientists have identified a protein in Salmonella bacteria that enables it to infect immune cells called macrophages. Seen here: Salmonella, isolated from infected macrophages. (Mildly color-enhanced.)
Scientists at Pacific Northwest National Laboratory (PNNL) have reported the first systematic investigation using global proteomics to identify changes in the abundance of bacterial proteins associated with macrophage colonization. These results demonstrate the utility of a systematic investigation of changes in the bacterial proteome to identify key proteins of likely importance in detecting bacterial pathogens and developing effective vaccines. The results appear in the September 29 issue of the Journal of Biological Chemistry.
Salmonella enterica serovar Typhimurium (STM) is a facultative intracellular pathogen that can cause gastroenteritis in humans and a lethal infection in mice that lack a functional natural resistance-associated macrophage protein 1 (Nramp1). Because the symptoms resemble human typhoid fever caused by STM, mice infected by STM provide a model system to investigate the development and immunology of typhoid fever in humans.
To evade host resistance mechanisms, STM must alter its proteome following macrophage infection. To identify new colonization and virulence factors that mediate STM production and development, PNNL researchers have isolated STM cells from RAW 264.7 (a mouse leukemic monocyte cell line) macrophages at various time points following infection and used the PNNL-developed accurate mass and time- (AMT-) tag proteomic approach to detect the changes in STM protein abundances.
Critical to the identification of key proteins linked to the successful colonization of macrophages, the scientists used the AMT-tag proteomic approach to systematically investigate the STM proteins isolated from the macrophages with or without functional Nramp1 at different time points of infection.
The research team includes Liang Shi, Josh Adkins, Jim Coleman, Athena Schepmoes, Alice Dohlnakova, Heather Mottaz, Angela Norbeck, Samuel Purvine, Nathan Manes, Heather Smallwood, Haixing Wang, Karin Rodland, Dick Smith, and Thomas Squier, all PNNL; John Forbes and Philippe Gros, McGill University, Montreal; Sergio Uzzau, University of Sassari, Italy; and Fred Heffron, Oregon Health Sciences University.
The work is supported by Laboratory Directed Research and Development at PNNL and by the National Institute of Allergy and Infectious Diseases.
See the PNNL news release, An infectious agent of deception, exposed through proteomics.
Reference
Shi L, JN Adkins, JR Coleman, AA Schepmoes, A Dohnalkova, HM Mottaz, AD Norbeck, SO Purvine, NP Manes, HS Smallwood, H Wang, J Forbes, P Gros, S Uzzau, KD Rodland, F Heffron, RD Smith, and TC Squier. 2006. "Proteomic analysis of Salmonella enterica serovar Typhimurium isolated from RAW 264.7 macrophages: identification of a novel protein that contributes to the replication of serovar Typhimurium inside macrophages." Journal of Biological Chemistry 281(39):29131-29140.
Learn more about this and other biological research being conducted by scientists in PNNL's Biological Sciences Division.