Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leukemia-inhibitory factor (LIF) is a neuropoietin able to regulate the differentiation and the survival of many cell types, which include some neuronal populations. The present study describes the genetic construction, expression, purification and properties of a diphtheria-toxin-related LIF gene fusion in which the native receptor-binding domain of diphtheria toxin was replaced with a gene encoding human LIF. The fusion protein expressed from the chimeric tox gene was designated DT-(1-389)-LIF-(2-184)-peptide. This fusion protein has a deduced molecular mass of 65980 Da and is formed by fusion of the first 389 amino acids of diphtheria toxin to amino acids 2-184 of mature human LIF, using a linker of 34 amino acids that includes six consecutive histidine residues. The latter span allows for single-step purification of the fusion protein by Ni(2+)-resin affinity chromatography. This linker provides a high degree of flexibility between the diphtheria toxin and LIF domains, thereby permitting aggregation-free refolding of the chimeric protein while bound to the affinity column. Both LIF and DT-(1-389)-LIF-(2-184)-peptide induced the phosphorylation of CLIP1 and CLIP2 in LIF-responsive neuroblastoma SH-N-BE cells. DT-(1-389)-LIF-(2-184)-peptide was selectively cytotoxic for cultured neuroblastoma cells bearing the LIF receptor, and for sympathetic neurons. The cytotoxic action of DT-(1-389)-LIF-(2-184)-peptide, like that of native diphtheria toxin, required receptor-mediated endocytosis, passage through an acidic compartment, and delivery of an ADP-ribosyltransferase to the cytosol of target cells. The latter point was confirmed by the fact that, while both LIF and DT-(1-389)-LIF-(2-184)-peptide increased c-fos mRNA expression in SH-N-BE cells, only LIF induced proenkephalin and c-fos promoter activities in cells transiently transfected with c-fos-chloramphenicol acetyltransferase and proenkephalin-chloramphenicol acetyltransferase fusion genes. Mutational analysis suggested that the C-terminal helix (helix D) of human LIF may, in part, constitute or contribute to the active site for LIF receptor binding and cell activation. The cytotoxic properties of DT-(1-389)-LIF-(2-184)-peptide may be useful in selectively depleting neuronal and immune cell populations that express the LIF beta receptor.
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PMID:Synthesis, cytotoxic properties and effects on early and late gene induction of a chimeric diphtheria toxin-leukemia-inhibitory factor protein. 891 49

Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis by production of the Rho GTPase-glucosylating toxins A and B. Recently emerging hypervirulent Clostridium difficile strains additionally produce the binary ADP-ribosyltransferase toxin CDT (Clostridium difficile transferase), which ADP-ribosylates actin and inhibits actin polymerization. Thus far, the role of CDT as a virulence factor is not understood. Here we report by using time-lapse- and immunofluorescence microscopy that CDT and other binary actin-ADP-ribosylating toxins, including Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin, induce redistribution of microtubules and formation of long (up to >150 microm) microtubule-based protrusions at the surface of intestinal epithelial cells. The toxins increase the length of decoration of microtubule plus-ends by EB1/3, CLIP-170 and CLIP-115 proteins and cause redistribution of the capture proteins CLASP2 and ACF7 from microtubules at the cell cortex into the cell interior. The CDT-induced microtubule protrusions form a dense meshwork at the cell surface, which wrap and embed bacterial cells, thereby largely increasing the adherence of Clostridia. The study describes a novel type of microtubule structure caused by less efficient microtubule capture and offers a new perspective for the pathogenetic role of CDT and other binary actin-ADP-ribosylating toxins in host-pathogen interactions.
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PMID:Clostridium difficile toxin CDT induces formation of microtubule-based protrusions and increases adherence of bacteria. 1983 54