Search results for "Enzyme complex"
showing 10 items of 55 documents
PKSP-dependent reduction of phagolysosome fusion and intracellular kill of Aspergillus fumigatus conidia by human monocyte-derived macrophages.
2002
Summary Previously, we described the isolation of an Aspergillus fumigatus mutant producing non-pigmented conidia, as a result of a defective polyketide synthase gene, pksP (polyketide synthase involved in pigment biosynthesis). The virulence of the pksP mutant was attenuated in a murine animal infection model and its conidia showed enhanced susceptibility towards damage by monocytes in vitro. Because macrophage-mediated killing is critical for host resistance to aspergillosis, the interaction of both grey-green wild-type conidia and white pksP mutant conidia with human monocyte-derived macrophages (MDM) was studied with respect to intracellular processing of ingested conidia. After phagocy…
Synthesis of pyrido[2,1-a]isoquinolin-4-ones and oxazino[2,3-a]isoquinolin-4-ones: New inhibitors of mitochondrial respiratory chain
2013
International audience; Benzo[a]quinolizine is an important heterocyclic framework that can be found in numerous bioactive compounds. The general scheme for the synthesis of these compounds was based on the preparation of the appropriate dihydroisoquinolines by Bischler-Napieralski cyclization with good yields, followed by the Pemberton method to form the oxazinones or pyridones derivatives via acyl-ketene imine cyclocondensation. All the synthesized compounds were assayed in vitro for their ability to inhibit mitochondrial respiratory chain. Most of the tested compounds were able to inhibit the integrated electron transfer chain, measured as NADH oxidation, which includes complexes I, III …
Male infertility and mitochondrial DNA
2004
The mitochondrial machinery plays a key role in the energy production and maintenance of spermatozoa motility. In this paper 200 idiopathic oligo-asthenozoospermic patients were classified on the basis of rapid progressive motility ("a") and sperm concentration. Mitochondrial enzymatic activity was studied and correlated to the viability of sperm cells. Mitochondrial DNA purified from both motile and non-motile sperm of the same individuals was amplificated using PCR. Results suggested that only motile sperm have organelles functional in oxygen consumption, unequivocally demonstrating that motility depends on the mitochondrial activity. Mitochondrial DNA of oligo-asthenozoospermic patients …
α-Synuclein expression levels do not significantly affect proteasome function and expression in mice and stably transfected PC12 cell lines
2004
α-Synuclein (α-syn) is a small protein of unknown function that is found aggregated in Lewy bodies, the histopathological hallmark of sporadic Parkinson disease and other synucleinopathies. Mutations in the α-syn gene and a triplication of its gene locus have been identified in early onset familial Parkinson disease. α-Syn turnover can be mediated by the proteasome pathway. A survey of published data may lead to the suggestion that overexpression of α-syn wild type, and/or their variants (A53T and A30P), may produce a decrease in proteasome activity and function, contributing to α-syn aggregation. To investigate the relationship between synuclein expression and proteasome function we have s…
Analysis of substrate binding in individual active sites of bifunctional human ATIC
2018
Aminoimidazolecarboxamide ribonucleotide formyl transferase (AICARFT): Inosine monophosphate cyclohydrolase (IMPCH, collectively called ATIC) is a bifunctional enzyme that catalyses the penultimate and final steps in the purine de novo biosynthesis pathway. The bifunctional protein is dimeric and each monomer contains two different active sites both of which are capable of binding nucleotide substrates, this means to a potential total of four distinct binding events might be observed. Within this work we used a combination of site-directed and truncation mutants of ATIC to independently investigate the binding at these two sites using calorimetry. A single S10W mutation is sufficient to blo…
Cloning of Sponge (Geodia cydonium) and Tunicate (Botryllus schlosseri) Proteasome Subunit Epsilon (PRCE): Implications about the Vertebrate MHC-Enco…
1996
Proteasomes are large protein complexes that play a major role in selective degradation of intracellular proteins. Eukaryotes feature seven different alpha and beta subunits. Two of the vertebrate housekeeping beta-subunits have MHC-encoded homologues that can substitute for the housekeeping counterparts upon interferon-gamma induction. In the present study we report the cloning of invertebrate beta-subunit proteasome epsilon (PRCE), from the marine sponge Geodia cydonium and from the colonial tunicate Botryllus schlosseri. Sequence comparisons revealed that the sponge and tunicate proteins are strikingly similar to vertebrate and yeast PRCEs and their MHC-linked counterparts the PRCCs (als…
Cryo-negative staining
1998
Abstract A procedure is presented for the preparation of thin layers of vitrified biological suspensions in the presence of ammonium molybdate, which we termcryo-negative staining. The direct blotting of sample plus stain solution on holey carbon supports produces thin aqueous films across the holes, which are routinely thiner than the aqueous film produced by conventional negative staining on a continuous carbon layer. Because of this, a higher than usual concentration of negative stain (ca. 16% rather than 2%) is required for cryo-negative staining in order to produce an optimal image contrast. The maintenance of the hydrated state, the absence of adsorption to a carbon film and associate…
Transporter (TAP)- and proteasome-independent presentation of a melanoma-associated tyrosinase epitope.
2000
The melanosomal protein tyrosinase is considered as a target of specific immunotherapy against melanoma. Two tyrosinase-derived peptides are presented in association with HLA-A2.1 [Wolfel et al., Eur. J. Immunol., 24, 759-764 (1994)]. Peptide 1-9 (MLLAVLYCL) is generated from the putative signal sequence. The internal peptide 369-377 is posttranslationally converted at residue 371, and its presentation is dependent on functional TAP transporters and proteasomes [Mosse et al., J. exp. Med.187, 37-48 (1998)]. Herein, we report on the processing and transport requirements for the signal sequence-derived peptide 1-9 that were studied in parallel to those for peptide 369-377. After infection of …
New molecular aspects of regulation of mitochondrial activity by fenofibrate and fasting
2000
Abstract Fenofibrate and fasting are known to regulate several genes involved in lipid metabolism in a similar way. In this study measuring several mitochondrial enzyme activities, we demonstrate that, in contrast to citrate synthase and complex II, cytochrome c oxidase (COX) is a specific target of these two treatments. In mouse liver organelles, Western blot experiments indicated that mitochondrial levels of p43, a mitochondrial T3 receptor, and mitochondrial peroxisome proliferator activated receptor (mt-PPAR), previously described as a dimeric partner of p43 in the organelle, are increased by both fenofibrate and fasting. In addition, in PPARα-deficient mice, this influence was abolishe…
Inhibition of the herpes simplex virus-coded thymidine kinase-complex by 9-?-D-arabinofuranosyladenine 5?-monophosphate (ara-AMP) and 9-(2-hydroxyeth…
1984
The thymidine kinase-complex isolated from herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) is associated with the following enzyme activities: ATP:dThd (dCyd) deoxypyrimidine kinase, ATP:dTMP thymidylate kinase, ADP:dThd- and AMP:dThd5′-phosphotransferase. In kinetic experiments it is shown that ara-AMP inhibits AMP:dThd- and ADP:dThd phosphotransferase activity, while acyclo-GMP impairs ADP:dThd phosphotransferase reaction only; the inhibition was found to be non-compertitive. The functional subunit ATP:dThd kinase was not affected by either compound.