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Antimikrobielle Peptide und Proteine spielen eine wichtige Rolle bei der angeborenen Immunabwehr. Sie sind auf verschiedenen Schleimhautoberflächen des Körpers zu finden, zum Beispiel auch in der Schleimschicht des Gastrointestinaltraktes. Beim Menschen sind drei Familien antimikrobiell wirksamer Peptide bekannt: die Defensine, die Cathelicidine und die Histatine. LL-37 ist das einzige Cathelicidin, das bisher beim Menschen gefunden wurde. Das Ziel der vorliegenden Arbeit war, den Effekt des probiotischen Bakteriums E. coli Nissle auf die LL-37-Genexpression in Kolonepithelzellen zu analysieren. Zunächst wurde hierfür die bakterizide Wirksamkeit von synthetischem LL-37 auf E. coli Nissle in vitro nachgewiesen. Anschließend wurde die antimikrobielle Aktivität verschiedener Kolonepithelzelllinien gegenüber E. coli Nissle untersucht und die LL-37-Genexpression in den Zelllinien bestimmt. Zwei der vier untersuchten Zelllinien (SW 620 und Geki-2) zeigten eine signifikante antimikrobielle Aktivität gegenüber E. coli Nissle. Die LL-37-Genexpression wurde in den Zelllinien T84 und Geki-2 gesteigert. Aus diesen Ergebnissen kann man folgern, dass die antimikrobielle Aktivität der Zelllinie Geki-2 auf eine erhöhte LL-37-Expression zurückzuführen ist, während die antimikrobielle Aktivität der Zelllinie SW 620 unabhängig von der LL-37-Expression ist. Die probiotische Wirksamkeit des Bakteriums E. coli Nissle könnte somit unter anderem durch eine Induktion der LL-37-Genexpression in differenzierten Kolonepithelzellen erklärt werden. / Antimicrobial peptides have been shown to play an important role in innate immunity. They have been found in different epithelial tissues of the human body, e.g. the colonic epithelium. In humans, antimicrobial peptides of three families have been identified: the defensins, cathelicidins and histatins. LL-37 is the only cathelicidin found in humans. The aim of this study was to analyze the effect of the probiotic E. coli Nissle on LL-37 gene expression in colonocytes. For this purpose we first demonstrated the bactericidal activity of synthetic LL-37 against E. coli Nissle in vitro. Furthermore, we investigated the antimicrobial activity of different colorectal cell lines against E. coli Nissle and the LL-37 gene expression in the cell lines. Two of four investigated cell lines (SW 620 and Geki-2) showed a significant antimicrobial activity against E. coli Nissle. The LL-37 gene expression was increased in the T84- and the Geki-2 cell line. This indicates, that the antimicrobial activity of Geki-2 cells depends on LL-37 gene expression, whereas the antimicrobial activity of SW 620 cells does not depend on LL-37 gene expression. Thus, the probiotic effect of E. coli Nissle could be explained by an induction of LL-37 gene expression in differentiated colorectal cells.

Integral membrane proteins perform a wide range of biological processes, including respiration, signal transduction and molecular transport. Structural information is necessary for a full understanding of the mechanisms by which integral membrane proteins work. Ferrous iron transporter protein B (FeoB) is an integral membrane protein of Escherichia coli which is considered to transport ferrous iron in to bacteria. But there are no definite proofs or clear indications of the precise mechanism of ferrous transport. By expressing and crystallizing the G-protein domain (FeoGP) and FeoB, it will be helpful to know about the iron transport system. In order to express FeoB and FeoGP, expression vector pFeoB (FeoB in pGEX-4T-1) and pFeoGP (FeoB in pGEX-4T-1) were made. FeoB and FeoGP proteins were expressed and purified. Using vapour diffusion method crystallization trials of FeoB and FeoGP were done. Crystals of FeoGP are observed and no crystal formation for FeoB. Native crystals of FeoGP diffracted to 2.2 ?? resolution, and mant-GMPPNP crystals to 2.6 ??. Preliminary data processing indicate space group P212121 for native crystals, with cell dimensions 46 x 119 x 146 ??. The data set is 100% complete, Rmerge 0.08, and I/ ?? 3.2.

1 v. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1992

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1988. / Vita. Abstract. Includes bibliographical references (leaves 51-60). Also available via the Internet.

Thesis (Ph. D.)--Georgia State University, 2007. / Title from file title page. Phang C. Tai, committee chair; John Houghton Parjit Kaur, Chung-Dar Lu, committee members. Electronic text (148 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Dec. 7, 2007. Includes bibliographical references (p. 125-140).

<p>Stafylococcus aureus, Stafylococcus epidermidis, Escherichia coli, Streptococcus</p><p>pyogenes och Bacillus sp. är bakterier som förekommer i vår normalflora eller runt om i</p><p>vår omgivning. De är i de allra flesta fall harmlösa men kan orsaka sjukdom ifall de</p><p>hamnar i t.ex. sår eller kontaminerar mat. Vissa av dessa bakterier har även en tendens att</p><p>utveckla resistens mot antibiotika, infektioner orsakade av resistenta bakterier kan bli</p><p>allvarliga och väldigt svåra att behandla. Detta är det främsta skälet till varför vi har valt</p><p>att undersöka ifall de ovan nämnda bakterierna förkommer på avdelningen SET på</p><p>Halmstad högskola. För att kunna identifiera de bakterier vi fann använde vi oss av en rad</p><p>olika biokemiska tester och resistensbestämningen utfördes bl.a. med hjälp av en PCR</p><p>körning. Vi fann alla de bakterier vi sökte efter förutom S. pyogenes och ingen av de</p><p>funna visade på någon resistens mot antibiotika.</p>

The mechanisms of substrate recognition by regulatory proteases are not well understood. Presently, two opposing models have arisen to describe E. coil Lon's ability to discriminate between substrates: one suggests the N-terminus involvement while the second suggests the C-terminus involvement. In this project, the role of the C-terminal domain as it relates to the recognition of Lon's normal physiological substrates RcsA, an activator of colanic acid capsular polysaccharide, and SulA, an inhibitor of cell division, was addressed. Using site-directed mutagenesis, five mutations in Lon (R537G, E538A, GS40W, R542G, R542P) were isolated. Their phenotypic impact was either similar in character to wildtype Lon (R537G, E538A) or ��lon cells (G540W, R542G, R542P). The stabilization of both RcsA and SulA based on phenotypic assays and immunological detection of lon* strains (G540W, R542G, R542P) suggests the C-terminal domain may be involved in substrate degradation as opposed to discriminator activity. / Graduation date: 2002

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.