Pertussis toxin export requires accessory genes located downstream from the pertussis toxin operon

Pertussis toxin, a major virulence factor of Bordetella pertussis, is an oligomeric protein composed of five different subunits that are exported individually to the periplasmic space by the signal peptide–dependent pathway. After assembly, the protein is exported from the periplasm to the extracellular compartment. We show that pertussis toxin secretion across the outer membrane requires the gene product of at least one gene (ptlC) that is located downstream from the pertussis toxin operon. The amino acid sequence of PtlC shows a high degree of homology to VirB4, a protein encoded by the virB operon, which contains 11 open reading frames that are involved in the transfer of T-DNA from Agrobaderium tumefaciens to the plant cells. This is a novel mechanism of protein export in Gram-negative bacteria.     

Conformational analysis of the dipeptide taste ligand L-aspartyl-D-2-aminobutyric acid-(S)-α-ethylbenzylamide and its analogues by NMR spectroscopy,computer simulations and X-ray diffraction studies

A dipeptide taste ligand L -aspartyl-D -2-aminobutyric acid-(S)-α-ethylbenzylamide was found to be about 2000 times more potent than sucrose. To investigate the molecular basis of its potent sweet taste, we carried out conformational analysis of this molecule and several related analogues by NMR spectroscopy, computer simulations and X-ray crystallographic studies. The results of the studies support our earlier model that an ‘L’-shape molecular array is essential for eliciting sweet taste. In addition, we have identified an aromatic group located between the stem and the base of the ‘L-shape’, which is responsible for enhancement of sweetness potency. In this study, we also assessed the optimal size of the essential hydrophobic group (X) and the effects of the chirality of the second residue toward taste. ©1997 European Peptide Society and John Wiley & Sons, Ltd.     

Heterocycle-containing tranylcypromine derivatives endowed with high anti-LSD1 activity

As regioisomers/bioisosteres of 1a, a 4-phenylbenzamide tranylcypromine (TCP) derivative previously disclosed by us, we report here the synthesis and biological evaluation of some (hetero)arylbenzoylamino TCP derivatives 1b-6, in which the 4-phenyl moiety of 1a was shifted at the benzamide C3 position or replaced by 2- or 3-furyl, 2- or 3-thienyl, or 4-pyridyl group, all at the benzamide C4 or C3 position. In anti-LSD1-CoREST assay, all the meta derivatives were more effective than the para analogues, with the meta thienyl analogs 4b and 5b being the most potent (IC₅₀ values = 0.015 and 0.005 μM) and the most selective over MAO-B (selectivity indexes: 24.4 and 164). When tested in U937 AML and prostate cancer LNCaP cells, selected compounds 1a,b, 2b, 3b, 4b, and 5a,b displayed cell growth arrest mainly in LNCaP cells. Western blot analyses showed increased levels of H3K4me2 and/or H3K9me2 confirming the involvement of LSD1 inhibition in these assays.     

Universal influenza B vaccine based on the maturational cleavage site of the hemagglutinin precursor

Conventional influenza vaccines can prevent infection, but their efficacy depends on the degree of antigenic "match" between the strains used for vaccine preparation and those circulating in the population. A universal influenza vaccine based on invariant regions of the virus, able to provide broadly cross-reactive protection, without requiring continuous manufacturing update, would solve a major medical need. Since the temporal and geographical dominance of the influenza virus type and/or subtype (A/H3, A/H1, or B) cannot yet be predicted, a universal vaccine, like the vaccines currently in use, should include both type A and type B influenza virus components. However, while encouraging preclinical data are available for influenza A virus, no candidate universal vaccine is available for influenza B virus. We show here that a peptide conjugate vaccine, based on the highly conserved maturational cleavage site of the HA(0) precursor of the influenza B virus hemagglutinin, can elicit a protective immune response against lethal challenge with viruses belonging to either one of the representative, non-antigenically cross-reactive influenza B virus lineages. We demonstrate that protection by the HA(0) vaccine is mediated by antibodies, probably through effector mechanisms, and that a major part of the protective response targets the most conserved region of HA(0), the P1 residue of the scissile bond and the fusion peptide domain. In addition, we present preliminary evidence that the approach can be extended to influenza A virus, although the equivalent HA(0) conjugate is not as efficacious as for influenza B virus.     

A human short-chain dehydrogenase/reductase gene: structure, chromosomal localization, tissue expression and subcellular localization of its product

We have previously described the cloning of Hep27, a short-chain dehydrogenase/reductase, which is synthesized in human hepatoblastoma HepG2 cells following growth arrest induced by butyrate treatment. The present report describes the cloning, the structure and the physical and cytogenetic mapping of the gene coding for Hep27. We also show that Hep27 is synthesized in a limited number of human normal tissues and that it is localized in the nuclei and cytoplasm of HepG2 cells.     

Measurement of homonuclear three-bond J(HNHα) coupling constants in unlabeled peptides complexed with labeled proteins: Application to a decapeptide inhibitor bound to the proteinase domain of the NS3 protein of hepatitis C virus (HCV)

A new isotope-filtered experiment has been designed to measure homonuclear three-bond J(H^NH) coupling constants of unlabeled peptides complexed with labeled proteins. The new experiment is based on the 3D HNHA pulse scheme, and belongs to the `quantitative J-correlation' type. It has been applied to a decapeptide inhibitor bound to the proteinase domain of the NS3 protein of human hepatitis C virus (HCV).     

Beauvericin Decreases Cell Viability of Wheat

Recently, beauvericin (BEA) has been recognized as an important toxic compound synthesized by several Fusarium strains, infecting maize, wheat, and rice, worldwide. The effects of BEA on mammalian cells have been studied; however, its effects on the function of host plant cells are largely unknown. The purpose of our work was to assess whether BEA can affect the root and leaf cells of wheat cultivar (cv.) ‘Arina’ seedlings, using a cytotoxicity assay and fluorescence microscopy. Toxigenicity during wheat germination was higher in BEA‐treated wheat seedlings than in non‐treated seedlings (control). Leaf primordial, situated at the base and the tips of treated leaves, were more affected by BEA compared to the control when assayed in medium for cell viability measured by luminescent equipment. BEA‐Treated plant cells secrete adenosine triphosphate (ATP) to the extracellular matrix and invoke more luminescence by luciferase than the non‐treated seedlings. Our results were confirmed by fluorescence microscopy following ‘4′,6‐diamidino‐2‐phenylindole’ (DAPI) staining and by confocal microscopy. In addition, the bioluminescent protein luciferase was observed in the intracellular space indicating presence of ATP. The incidence of nuclear fragmentation increased significantly in cells of seedlings treated with BEA at 40 μM concentration implying that the intracellular phytotoxin BEA plays an important role, possibly as a mediator in cell‐death signalling.     

In vivo activation of renal phospholipase activity by bradykinin in the rat

Activation of a renal acylhydrolase by bradykinin (BK) with subsequent release of prostaglandins precursor arachidonic acid has been postulated but not yet demonstrated. BK was infused into the left artery of 27 rats which were subdivided into 9 groups according to BK concentration (10, 100 and 1000 ng/min) and time of infusion (20, 40 and 60 min). The rats were then sacrificed and the left to right ratio of renal phospholipase activity was determined. The data obtained were processed by a factorial analysis of variance which allowed the effect of BK and the time of infusion to be evaluated independently as well as interdependently. The results of the statistical analysis showed that phospholipase activity depends on both BK dosage and infusion time and that there is no interaction between dose and time. These findings offer evidence for the “in vivo” activation of the kidney phospholipase activity by BK.