Bacterial surface

The Nature of the Bacterial Surface. M. Stacey, Blackwell Oxford, (1949). 

M Sumper. In TJ Beveridge, SE Koval, eds. Advances in Paracrystalline Bacterial Surface Layers. New York Plenum Press, 1993, pp 109-117. 

Although ribosomal proteins are readily observed as in Figures 13.7 and 13.8 altered matrix conditions can alter the relative ionization of bacterial whole-cell compounds. A systematic analysis involving laser power/fluence and sample preparation conditions reveals that if the concentrated trifluo-roacetic acid is added and the laser power increased above optimal conditions, ionization of bacterial surface compounds can be enhanced. Figure 13.9 is the resulting 9.4 T MALDI-FTMS, seen are both the Braun s lipoprotein56,57 and the Murein lipoprotein. Both of these compounds are complex combinations of hydrocarbon lipids attached to a protein base. This is the first MALDI-FTMS observation of surface proteins desorbed directly from whole cells by influencing ionization conditions. 

Kim SH, Shin DS, Oh MN, Chung SC, Lee JS, Oh KB. Inhibition of the bacterial surface protein anchoring transpeptidase sortase by isoquinoline alkaloids. Biosci Biotechnol Biochem 2004 68 421-424. 

Fowle and Fein (1999) measured the sorption of Cd, Cu, and Pb by B. subtilis and B. licheniformis using the batch technique with single or mixed metals and one or both bacterial species. The sorption parameters estimated from the model were in excellent agreement with those measured experimentally, indicating that chemical equilibrium modeling of aqueous metal sorption by bacterial surfaces could accurately predict the distribution of metals in complex multicomponent systems. Fein and Delea (1999) also tested the applicability of a chemical equilibrium approach to describing aqueous and surface complexation reactions in a Cd-EDTA-Z . subtilis system. The experimental values were consistent with those derived from chemical modeling. 

Fein JB, Daughney CJ, Yee N, Davis TA (1997) A chemical equilibrium model for metal adsorption onto bacterial surfaces. Geochim Cosmochim Acta 61 3319-3328... 

Fein JB, Martin AM, Wightman PG (2001) Metal adsorption onto bacterial surfaces development of a predictive approach. Geochim Cosmochim Acta 65 4267 4273... 

The hydroxyl groups at C-2 and C-3 are not essential for the catalytic reaction. McNicol and Baker233 showed that the endopectate lyases of Bacillus sphaericus and Bacillus polymyxa degrade the Vi antigen, the bacterial-surface polysaccharide containing a-D-(1 — 4)-linked residues of 2-acetamido-3-0-acetyl-2-deoxy-D-galac-topyranuronate, in the same way as its O-deacetylated derivative and D-galacturonan. 

A well-studied example of a bioemulsifier is emulsan, a cell surface-exposed molecule that allows Acinetobacter calcoaceticus RAG-1 to attach to crude oil droplets [123]. Upon depletion of the short-chain alkanes utilised by this strain, the emulsan molecules were released from the bacterial surface, thereby allowing the cells to leave the oil droplet and to find a new substrate. Important positive side-effects of this mechanism seem to be that the remaining emulsan hydrophilises the droplet and prevents both the reattachment of A. calcoaceticus RAG-1 and the coalescence of the used oil droplet with other droplets that still contain unexploited alkanes. Bredholt et al. [124] studied the oil-emulsifying activity of Rhodococcus sp. strain 094. When exposed to inducers of crude-oil emulsification, the cells developed a strongly hydrophobic character, which was rapidly lost when crude-oil emulsification started. This indicated that the components responsible for the formation of cell-surface hydrophobi-city acted as emulsion stabilisers after release from the cells. 

Neu, T. R. (1996). Significance of bacterial surface-active compounds in interaction of bacteria with interfaces, Microbiol. Rev., 60, 151-166. 

The precise function of many acute-phase proteins is not known. C-reactive protein binds lipids, whilst a-macroglobulin and ceruloplasmin can scavenge some reactive oxygen metabolites. However, many acute-phase proteins are glycoproteins and can bind to bacterial surfaces hence, they may serve as non-specific opsonins for phagocytosis, and their synthesis is stimulated by IL-1 and IL-6. 

Edwards, S. W. (1989). Interactions between bacterial surfaces and phagocyte plasma membranes. Biochem. Soc. Trans. 17,460-2. 

Hydrophobicity of the bacterial surface affects the van der Waals interaction by changing (increasing) the Hamaker Constant AbSw (valid for the interaction of a bacterium (b) with a surface (s) in water (w) (Eq. (3) and footnote c in Table 7.3). As we have seen in the Appendix of Chapter 4, the extent of hydrophobicity is related to the contact angle which is formed by a drop of water on a layer of a bacterial cell. (The larger the contact angle the more hydrophobic is the surface.)... 

Hydrophobin-protein interactions include those bacterial surface components that promote adhesion to host cell surfaces via hydrophobic moieties that are often thought to be nonspecific (Rosenberg and Doyle, 1990 Rosenberg and Kjelleberg, 1986 Rosenberg et al, 1996). 

The initial adherence of pathogens to host cell surfaces is considered an essential step in colonization and infection (Savage, 1977, 1984). Therefore, identifying the bacterial molecules that mediate adherence has been a major area of research, especially since these molecules may serve as targets for anfi-adherence strategies. As discussed previously (Section VI), the detailed interactions between a pathogen and a host cell are often mediated by proteinaceous surface structures on the bacterial surface. These bacterial proteins are referred to as adhesins (Finlay and Falkow, 1989), and are most often foimd on the tips of bacterial fimbriae or pili (fimbrial adhesins), but may also be anchored in the bacterial membrane so that it can be presented on the bacterial outer membrane (afimbrial adhesins) (Sharon and Ofek, 1986). Models of fimbrial and afimbrial adhesins of some human pathogens are discussed here. 

Dean, P., and Kenny, B. (2004). Intestinal barrier dysfunction by enteropathogenic Escherichia coli is mediated by two effector molecules and a bacterial surface protein. Mol. Microbiol. 54, 665-675. 

Striking is the resemblance between our model structure and the multi-stranded -barrels known for various membrane proteins [42] and poreforming toxins [43]. The formation of an aqueous pore in the lipid bilayer would indeed offer an explanation for the observed bilayer conductivity induced by gramicidin S upon membrane binding [6]. The peptidedipid ratio of 1 40 at which this structure could be trapped for NMR analysis appears to be biologically relevant, as the minimum inhibitory concentration of gramicidin S corresponds to far more than an equimolar ratio of peptides per lipid molecule on the bacterial surface [34,35]. 

Proteolytic cleavage of factor C3 provides two components with different effects. The reaction exposes a highly reactive thioester group in C3b, which reacts with hydroxyl or amino groups. This allows C3b to bind covalently to molecules on the bacterial surface (opsonization, right). In addition, C3b initiates a chain of reactions leading to the formation of the membrane attack complex (see below). Together with C4a and C5a (see below), the smaller product C3a promotes the inflammatory reaction and has chemotactic effects. 

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