Identification of the major outer membrane proteins of Aeromonas salmonicida

Abstract

Aeromonas salmonicida subsp. salmonicida is a Gram-negative bacterium that is the etiological agent of furunculosis, a serious infectious disease of salmonids. Aeromonas spp. are ubiquitous waterborne bacteria responsible for a wide spectrum of diseases among aquatic organisms and humans. Bacterial outer membrane proteins (OMPs) play a significant role in virulence as they comprise the outermost surface in contact with host cells and immune defense factors. To identify the major OMPs of A. salmonicida a proteomic analysis was undertaken using a carbonate OMP-enrichment protocol. The enriched OMP-extracts were separated by 2-dimensional electrophoresis (2-DE) and the spots identified using liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) via an electrospray ionization source. In total, 76 unique proteins were identified from the 125 spots observed on the 2-D gel. The surface layer (S-layer) VapA protein dominated the A. salmonicida OMP 2-D profile, accounting for 60% of the protein on the 2-D gels. Among the other outer membrane proteins identified were at least 10 porins and various receptors involved in nutrient acquisition. Also identified in the carbonate insoluble fraction were phosphoglycerate kinase, enolase and others that lacked classical export sorting signals. The putative association of these proteins with the cell surface might provide new insights concerning the biological and pathogenic roles of these molecules in A. salmonicida infection. This work represents the first systematic attempt to characterize the cell surface of A. salmonicida.

Cytosolic Proteins Contribute to Surface Plasminogen Recruitment ofNeisseria meningitidis

“…Enolase, a 46-kDa glycolytic enzyme, is highly conserved in prokaryotes and eukaryotes. Even though no signal peptide for secretion or localization to the outer membrane has yet been identified, enolases of bacteria and eukaryotic cells have been shown to be localized in the outer membrane (11,21,43,56,60). Indeed, the recruitment of plasminogen to cellular surfaces by enolase seems to be a conserved pattern in different cells, including bacteria, fungi, and eukaryotic cells (5,36,38,41,46).…”

Proteomic and bioinformatic analysis of outer membrane proteins of the protobacterium Bartonella henselae (Bartonellaceae)

“…In recent years, advances in the solubilization of intractable proteins have prompted the proteomic analysis of OMPs, especially in various bacteria including Escherichia coli (Molloy et al, 2000), Aeromonas salmonicida (Ebanks et al, 2005) and Dickeya dadantii (Babujee et al, 2007). Because of the importance of OMPs for the molecular basis of pathogenesis and diagnosis and advances of 2-DE technique, we focused on these fractions and developed a technique for 2-DE of Bartonella OMPs using carbonate incubation compared with sodium lauryl sarcosine incubation for evaluating the differentiation of the two OMP extraction methods, followed by improved solubilization conditions for array by 2-DE using the zwitterionic detergent ZWITTERGENT 3-10, ASB-14 and immobilized pH gradients.…”

Prevalence of different outer membrane proteins in isolates of Aeromonas species

“…High intensity bands were obtained at the region of 25-45 kDa. Ebanks et al (2005) recorded 10 outer membrane proteins in the same region which included homologues of OMPC, OMPAI/AII, OMPK, OMPTolC, OMPD and other Omps involved in nutrient acquisition in A. salmonicida by proteomics. In this study, no protein bands were obtained in the Omp preparations of Aeromonas isolates in the region of 73, 76 and 85 kDa which are known to be expressed under iron limiting conditions (Ebanks et al 2004).…”

“…Several laboratories have identified A layer positive strains of A. hydrophila (HG1) and A. veronii biotype sobria (HG8, phenospecies sobria) involved in animal and human infections (Janda 1991). Bacterial outer membrane proteins (Omps) play a significant role in virulence as they comprise the outermost surface in contact with host cells and immune defense factors (Ebanks et al 2005). Porins are essential for bacterial metabolism and act as the major uptake channel for certain antibiotics.…”