Extracellular Proteome of a Highly Invasive Multidrug-resistant Clinical Strain of Acinetobacter baumannii

The study of the extracellular proteomes of pathogenic bacteria is essential for gaining insights into the mechanisms of pathogenesis and for the identification of virulence factors. Through the use of different proteomic approaches, namely Nano-LC and 2DE combined with MALDI-TOF/TOF, we have charac...

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Bibliographic Details
Published in:Journal of proteome research 2012-12, Vol.11 (12), p.5678-5694
Main Authors: Mendez, Jose Antonio, Soares, Nelson C, Mateos, Jesús, Gayoso, Carmen, Rumbo, Carlos, Aranda, Jesús, Tomas, Maria, Bou, Germán
Format: Article
Language:English
Subjects:
Acinetobacter baumannii - drug effects
Acinetobacter baumannii - enzymology
Acinetobacter baumannii - pathogenicity
Animals
Bacterial Outer Membrane Proteins - analysis
Bacterial Secretion Systems
Cell Line, Tumor
Cell Membrane - enzymology
Culture Media - metabolism
Drug Resistance, Multiple, Bacterial
Electrophoresis, Gel, Two-Dimensional
Extracellular Space - enzymology
Hydrogen Peroxide - pharmacology
Macrophages - metabolism
Macrophages - microbiology
Mice
Microbial Viability
Oxidative Stress
Protein Transport
Proteome - analysis
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods
Virulence Factors - metabolism
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Summary:The study of the extracellular proteomes of pathogenic bacteria is essential for gaining insights into the mechanisms of pathogenesis and for the identification of virulence factors. Through the use of different proteomic approaches, namely Nano-LC and 2DE combined with MALDI-TOF/TOF, we have characterized the extracellular proteome of a highly invasive, multidrug-resistant strain of A. baumannii (clone AbH12O-A2). This study focused on two main protein fractions of the extracellular proteome: proteins that are exported by outer membrane vesicles (OMVs) and freely soluble extracellular proteins (FSEPs) present in the culture medium of A. baumannii. Herein, a total of 179 nonredundant proteins were identified in the OMV protein fraction and a total of 148 nonredundant proteins were identified in FSEP fraction. Of the OMV proteins, 39 were associated with pathogenesis and virulence, including proteins associated with attachment to host cells (e.g., CsuE, CsuB, CsuA/B) and specialized secretion systems for delivery of virulence factors (e.g., P. pilus assembly and FilF), whereas the FSEP fraction possesses extracellular enzymes with degradative activity, such as alkaline metalloprotease. Furthermore, among the FSEP we have detected at least 18 proteins with a known role in oxidative stress response (e.g., catalase, thioredoxin, oxidoreductase, superoxide dismutase). Further assays demonstrated that in the presence of FSEPs, bacterial cells withstand much higher concentrations of H2O2 showing higher survival rate (approximately 2.5 fold) against macrophages. In this study we have identified an unprecedented number of novel extracellular proteins of A. baumannii and we provide insight into their potential role in relevant processes such as oxidative stress response and defense against macrophage attack.
ISSN:1535-3893
1535-3907
DOI:10.1021/pr300496c