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ARTS IN EPITHELIAL CELLS: EXPRESSION AND REGULATION
No full text/Volumes/Disco Storage Enrico/Unicam/prodotti ricerca UNICAM/Meetings/NAD2008.pd
Le nuove strutture intermedie : modelli organizzativi, target di utenti e formule di servizio
No full textMONO ADP-RIBOSYLTRANSFERASES EXPRESSED ON THE SURFACE OF PULMONARY EPITHELIAL CELLS ARE REGULATED BY PATHOGEN-ASSOCIATED MOLECULAR PATTERNS
Full text linkMono ADP-ribosylation is a post-translational modification catalyzed by a family of enzymes, related to bacterial toxins, which possess adenosine diphosphate ribosyltransferase activity (ARTs). The expression of ART1, 3 and 4 at the apical surface of airway cells is consistent with the possibility that ARTs may have a role in inflammatory response. Since several studies have evidenced that Toll-like receptors (TLRs) are expressed in lung epithelial cells and given that there are a number of potential TLR agonists in the lung, we evaluated whether airway epithelial cells express transferase activity. We have assessed that A549 cells express ART1 on their surface and shown that lipotheicoic acid (LTA) and flagellin, but not lipopolysaccaride (LPS), peptidoglycan (PG) and poly (I:C), up-regulate ART1. This cell line was used to determine how bacterial components of Gram+ and Gram- bacteria affect ART activity and/or expression. The expression of ART1 relative to the actin obtained by qRT-PCR confirm the up-regulation exerted on ART1 gene by LTA but not by PAM and flagellin. LPS, LTA, PG, flagellin or poly(I:C) did not induce the expression of either ART3 or ART5 mRNA, while a strong stimulatory effect on ART4 mRNA expression was found after stimulation of cells with LPS, LTA and PG but not flagellin and poly(I:C). A pretreatment of cells with mAbs that antagonize TLR4 and TLR2, inhibited ART4 activation indicating TLR4 and TLR2 involved in the mediation of ART4 induction. The incubation with TLR2 antagonist specifically blocks the ART1 up-regulation by LTA indicating that the effect is mediated by this receptor
ROLE OF IRON IN CATALYTIC REGULATION OF THE NEISSERIA MENINGITIDIS ADP-RIBOSYLTRANSFERASE ENZYMATIC ACTIVITIES
Full text linkAmong the several toxins used by pathogens to target and kill host cells, proteins that catalyze the ADP-ribosylation reaction represent a family of well characterized enzymes. ADP-ribosylating toxins split the N-glycosidic bond of NAD+ that act as donor of the ADP-ribose moiety, which is selectively linked to specific amino-acids onto protein targets, and nicotinamide, which is simultaneously released. A novel pattern-based computational approach, allowed us to identify NarE (Neisseria ADP-ribosylating enzyme), a previously unidentified ADP-ribosyltransferase, in strain MC58 of the gram-negative aerobic-anaerobic facultative N. meningitidis [1]. NarE retains the ability to ADP-ribosylate arginine and small guanidine compounds like agmatine and to hydrolase NAD in ADP-ribose and nicotinamide (nam) in the absence of ADP-ribose acceptor [2]. A combination of biophysical methods (UV-spectra, EPR) were used to show that NarE contains an iron-sulfur (Fe-S) centre. The native state of the protein shows a complex resonance with g values equal to 4.4, 4.3 and 4.2, indicative of a high spin ferric iron. The iron content of NarE preparation determined by colorimetric assay and by Atomic Absorption Spectrophotometer that converged to a ratio <1-Fe atom per monomer and the structural information obtained by EPR resembled those present in the rubredoxin protein family. Substitution of C67 and C128 into serine caused a reduction in the E420/E280 ratio from 2.3 to 0.72 x 102 indicating the absence of a stable cluster. The mutagenized NarE exerted a consistent decrease of the ADP-ribosyltransferase activity while NAD-glycohydrolase activity remained unaltered [3]. Recent observations indicate that the iron oxidation state exerts a selective regulation of the NarE enzymatic activities. In the presence of the oxidized form of iron (Fe3+) NarE transferase activity is enhanced while the reduced form (Fe2+) is more active on NAD-glycohydrolase activity. Effects exerted by ferric and ferrous iron were reversed when enzymatic activity were measured in the presence of O-phenanthroline, a potent iron chelator. Therefore the iron through its oxidation state could confer on NarE a new role in Neisseria metabolism
CD : Londra città molteplice. Architettura della rigenerazione
No full textIl CD interattivo contiene una documentazione integrativa su alcune opere selezionate tra quelle trattate nel testo: N.Trasi, D.Fondi, M.Del Vecchio (a cura di) Londra città molteplice
Ed. Kappa, Roma, 200
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