Surface layer proteins structure

Hynonen U, Palva A. Lactobacillus surface layer proteins structure, function and applications. Appl Microbiol Biotechnol. 2013 97 5225 3. doi 10.1007/s00253-013 962-2. 

Peters, J., Baumeister, W., and Lupas, A. (1996). Hyperthermostable surface layer protein tetrabrachion from the archaebacterium Staphylothermus marinusr. Evidence for the presence of a right-handed coiled coil derived from the primary structure. / Mol. Biol. 257, 1031-1041. 

Biotemplates have been fabricated from two-dimensional crystalline surface proteins for the subsequent electrochemical deposition of nanowire structures [82]. These surface layer proteins encapsulate certain bacterial cells, controlling extracellular transport. They form especially robust thin films over cells, and are resistant to conditions that normally denature proteins, such as low pH and heat, thus making them ideal as template materials for electrodeposition. Schwartz and coworkers investigated a hexagonally packed intermediate surface layer protein from... 

Tissue response is determined by a sequence of events that occurs at several different time and length scales. After hydration of the implanted surface, which occurs on a microsecond timescale, small molecules migrate toward the surface in milliseconds, and protein over a timescale of minutes. Subsequent cell attachment that occurs over the adsorbed protein layers determines the long term tissue response of the implanted material. Each of these processes needs to be characterized and understood when designing the surface to elicit the required tissue response. Some features of the surface layer that are typically monitored include macroscopic characteristics such as the thickness and the surface energy of the layer, the hydration state of the surface layer, the structure and conformation of... 

The structural model sketched in Figure 6 was based [28, 29] on the electron density profile and the available knowledge of the lipid, dipalmitoylphosphatidylethanolamine (DPPE) and of the surface layer protein from B. sphaericus CCM2177. 

Figure 6 Artist s view of lipid/protein interaction derived from the electron density model from XR measurements and available structural data. The lipid monolayer is dipalmitoyl phosphatidyl ethanolamine (DPPE) and the protein is a membrane surface layer protein from B. sphaericus (from ref. [28]). The structural model sketched was based [28, 29] on the electron density profile (black line) inverted from measured reflectivity data as described in the text.

In order to enhance the stability of hposomes and to provide a biocompatible outermost surface shucture for controlled immobihzation (see Section IV), isolated monomeric and oligomeric S-layer protein from B. coagulans E38/vl [118,123,143], B. sphaericus CCM 2177, and the SbsB from B. stearothermophilus PV72/p2 [119] have been crystallized into the respective lattice type on positively charged liposomes composed of DPPC, HD A, and cholesterol. Such S-layer-coated hposomes are spherical biomimetic structures (Fig. 18) that resemble archaeal ceUs (Fig. 14) or virus envelopes. The crystallization of S-... 

Myelin in situ has a water content of about 40%. The dry mass of both CNS and PNS myelin is characterized by a high proportion of lipid (70-85%) and, consequently, a low proportion of protein (15-30%). By comparison, most biological membranes have a higher ratio of proteins to lipids. The currently accepted view of membrane structure is that of a lipid bilayer with integral membrane proteins embedded in the bilayer and other extrinsic proteins attached to one surface or the other by weaker linkages. Proteins and lipids are asymmetrically distributed in this bilayer, with only partial asymmetry of the lipids. The proposed molecular architecture of the layered membranes of compact myelin fits such a concept (Fig. 4-11). Models of compact myelin are based on data from electron microscopy, immunostaining, X-ray diffraction, surface probes studies, structural abnormalities in mutant mice, correlations between structure and composition in various species, and predictions of protein structure from sequencing information [4]. 

Some protein structures limit the kinds of amino acids that can occur in the J3 sheet. When two or more /3 sheets are layered close together within a protein, the R groups of the amino acid residues on the touching surfaces must be relatively small. J3-Keratins such as silk fibroin and the fibroin of spider webs have a very high content of Gly and Ala residues, the two amino acids with the smallest R groups. Indeed, in silk fibroin Gly and Ala alternate over large parts of the sequence. 

To interact with bases in the major groove of DNA, a protein requires a relatively small structure that can stably protrude from the protein surface. The DNA-binding domains of regulatory proteins tend to be small (60 to 90 amino acid residues), and the structural motifs within these domains that are actually in contact with the DNA are smaller still. Many small proteins are unstable because of their limited capacity to form layers of structure to bury hydrophobic groups (p. 118). The DNA-binding motifs provide either a very compact stable structure or a way of allowing a segment of protein to protrude from the protein surface. 

Other bacterial coats. Archaebacteria not only have unusual plasma membranes that contain phytanyl and diphytanyl groups (Section A,3)608 but also have special surface layers (S-Iayers) that may consist of many copies of a single protein that is anchored in the cell membrane.609 The surface protein of the hypothermic Staphylothermus marius consists of a complex structure formed from a tetramer of 92-kDa rods with an equal number of 85-kDa "arms."610 611 S-layers are often formed not only by archaebacteria but also by eubacteria of several types and with quite varied structures.612 14 While many bacteria carry adhesins on pili, in others these adhesive proteins are also components of surface layers.615 Additional sheaths, capsules, or slime layers, often composed of dextrans (Chapter 4) and other carbohydrates, surround some bacteria. 

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