Identification of surface proteins in Enterococcus faecalis V583

<p>Abstract</p> <p>Background</p> <p>Surface proteins are a key to a deeper understanding of the behaviour of Gram-positive bacteria interacting with the human gastro-intestinal tract. Such proteins contribute to cell wall synthesis and maintenance and are important for interactions between the bacterial cell and the human host. Since they are exposed and may play roles in pathogenicity, surface proteins are interesting targets for drug design.</p> <p>Results</p> <p>Using methods based on proteolytic "shaving" of bacterial cells and subsequent mass spectrometry-based protein identification, we have identified surface-located proteins in <it>Enterococcus faecalis </it>V583. In total 69 unique proteins were identified, few of which have been identified and characterized previously. 33 of these proteins are predicted to be cytoplasmic, whereas the other 36 are predicted to have surface locations (31) or to be secreted (5). Lipid-anchored proteins were the most dominant among the identified surface proteins. The seemingly most abundant surface proteins included a membrane protein with a potentially shedded extracellular sulfatase domain that could act on the sulfate groups in mucin and a lipid-anchored fumarate reductase that could contribute to generation of reactive oxygen species.</p> <p>Conclusions</p> <p>The present proteome analysis gives an experimental impression of the protein landscape on the cell surface of the pathogenic bacterium <it>E. faecalis</it>. The 36 identified secreted (5) and surface (31) proteins included several proteins involved in cell wall synthesis, pheromone-regulated processes, and transport of solutes, as well as proteins with unknown function. These proteins stand out as interesting targets for further investigation of the interaction between <it>E. faecalis </it>and its environment.</p

Experimental investigation on the fiber preform deformation due to mold closure for composites processing

In liquid composite molding processes, e.g., resin transfer molding, fiber preforms deform when mold is closed. This deformation of fiber preform due to mold closure causes inconsistencies to the permeability, and thus has a negative impact on resin flow. The variations in resin flow cause defects, e.g., dry spots and voids, resin-rich surfaces/zones, fiber distortions, which result in large variations in the product dimensions and mechanical performance. Thus, good understanding of the effects of process parameters on the deformation of fiber preform is necessary for developing high-quality affordable composites. An experimental study on the deformation of fiber preform for making angle-shaped composite parts is presented in this paper. The effects of enclosed angle, radius, fiber volume fraction, and stacking sequence were studied efficiently using design of experiments (DOE). Two open-channel molds were designed and fabricated for varying the design parameters. In each experiment run, the fiber preform was loaded into the mold and the mold was closed. The gaps formed between the fiber preform and inner mold surface were visually inspected by a microscope, and quantitatively characterized. The data were then analyzed. It is shown from the experiments that gaps occur at two locations: at corner radii and beside corner radii. The following conclusions are drawn from this experimental study: (1) fiber volume fraction is the most significant factor affecting the gaps at corner radii, and the gap thickness decreases with increasing fiber volume fraction; (2) the gap thickness decreases with increasing radius; and (3) the gap thickness of unidirectional preforms is larger than that of the cross-ply preforms