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31.
Sally Badawi Feda E. Mohamed Divya Saro Varghese Bassam R. Ali 《Traffic (Copenhagen, Denmark)》2023,24(8):312-333
Endoplasmic reticulum-associated protein degradation (ERAD) is a stringent quality control mechanism through which misfolded, unassembled and some native proteins are targeted for degradation to maintain appropriate cellular and organelle homeostasis. Several in vitro and in vivo ERAD-related studies have provided mechanistic insights into ERAD pathway activation and its consequent events; however, a majority of these have investigated the effect of ERAD substrates and their consequent diseases affecting the degradation process. In this review, we present all reported human single-gene disorders caused by genetic variation in genes that encode ERAD components rather than their substrates. Additionally, after extensive literature survey, we present various genetically manipulated higher cellular and mammalian animal models that lack specific components involved in various stages of the ERAD pathway. 相似文献
32.
Ashraf Asadi Sofilar Akram Shirdel Vahab Jafarian Khosrow Khalifeh 《Luminescence》2023,38(11):1946-1954
Mnemiopsin 1 (Mn1) and Mnemiopsin 2 (Mn2) are photoproteins found in Mnemiopsis leidyi. We have tried to answer the question of whether the structural features of photoproteins can explain the observed activity data. According to the activity measurements data, they have the same characteristic wavelength. However, the initial intensity of Mn2 is significantly higher than that of Mn1, and decay time of Mn1 (0.92 s−1) is lower than that of Mn2 (1.46 s−1). The phylogenetic analysis demonstrates that, compared with Obelin and Aequorin from Obelia longissima and Aequorea victoria, respectively, a gene modification event may have caused the expansion of the N-terminal side of all photoproteins from M. leidyi. An in silico study has shown that the stability of the photoprotein–substrate complex of Mn2 is higher than that of Mn1, indicating a higher affinity of the substrate for Mn2 compared with Mn1. It was revealed that the active EF-hand loops 1 and III in Mn2 is locally more rigid compared with those in Mn1. We concluded that different stability of the photoprotein complexes leads to different initial intensity. While different patterns of the local dynamics of loops I and III may influence the decay rate. 相似文献
33.
Lucia Pitzurra Manuela Puliti Mohamed Ali Burhan Fuad Francesco Bistoni Elisabetta Blasi 《FEMS immunology and medical microbiology》1993,7(4):289-295
Abstract The present study was designed to establish the susceptibility of macrophage-mediated effector functions to tetanus toxin (TT). Using the murine macrophage cell line, GG2EE, generated in vitro by v- raf /v- myc oncogenes, we have previously provided evidence that TT selectively inhibits interferon gamma (IFN-γ), but not basal, lysozyme activity. Here we show that while neither phagocytic nor candidacidal activities are affected by TT treatment, antitumoral activity is significantly impaired after exposure to TT. This phenomenon, which is dose-dependent, is fully ascribed to the holotoxin, as heat inactivated TT, C or A-B fragments result ineffective. Furthermore, C but not A-B fragment competes with TT in abrogating its inhibitory effects. Overall, these data indicate that TT is not a broad-spectrum, down-regulating signal on macrophage-mediated functions, thus implying that its toxic action is exerted on specific molecular targets. 相似文献
34.
Strains of Escherichia coli have been produced which express very high levels of the tRNAleu1 isoacceptor. This was accomplished by transforming cells with plasmids containing the leuV operon which encodes three copies of the tRNALeu1 gene. Most transformants grew very slowly and exhibited a 15-fold increase in cellular concentrations of tRNALeu1 As a result, total cellular tRNA concentration was approximately doubled and 56% of the total was tRNALeu1. We examined a number of parameters which might be expected to be affected by imbalances in tRNA concentration: in vivo tRNA charging levels, misreading, ribosome step time, and tRNA modification. Surprisingly, no increase in intracellular ppGpp levels was detected even though only about 40% of total leucyl tRNA was found to be charged in vivo. Gross ribosomal misreading was not detected, and it was shown that ribosomal step times were reduced between two- and threefold. Analyses of leucyl tRNA isolated from these slow-growing strains showed that at least 90% of the detectable tRNALeu1 was hypomodified as judged by altered mobility on RPC-5 reverse-phase columns, and by specific modification assays using tRNA(m1G)-methyltransferase and pseudo-uridylate synthetase. Analysis of fast-growing revertants demonstrated that tRNA concentration per se may not explain growth inhibition because selected revertants which grew at wild-type growth rates displayed levels of tRNA comparable to that of control strains bearing the leuV operon. A synthetic tRNALeu1 operon under the control of the T7 promoter was prepared which, when induced, produced six- to sevenfold increases in tRNALeu1 levels. This level of tRNALeu1 titrated the modification system as judged by RPC-5 column chromatography. Overall, our results suggest that hypomodified tRNA may explain, in part, the observed effects on growth, and that the protein-synthesizing system can tolerate an enormous increase in the concentration of a single tRNA. 相似文献
35.
Shafiq Fahad Iqbal Muhammad Raza Syed Hammad Akram Nudrat Aisha Ashraf Muhammad 《Journal of Plant Growth Regulation》2023,42(3):1267-1290
Journal of Plant Growth Regulation - Fullerenols are carbon nanoparticles that have been declared as free radical sponges. There is a need to take a prudent path toward its applications in various... 相似文献
36.
Sarrah M'Barek Ziad Fajloun Sandrine Cestle Christiane Devaux Pascal Mansuelle Amor Mosbah Besma Jouirou Massimo Mantegazza Jurphaas van Rietschoten Mohamed El Ayeb Herv Rochat Jean‐Marc Sabatier Francois Sampieri 《Journal of peptide science》2004,10(11):666-677
Aah I is a 63-residue alpha-toxin isolated from the venom of the Buthidae scorpion Androctonus australis hector, which is considered to be the most dangerous species. We report here the first chemical synthesis of Aah I by the solid-phase method, using a Fmoc strategy. The synthetic toxin I (sAah I) was renatured in DMSO-Tris buffer, purified and subjected to thorough analysis and comparison with the natural toxin. The sAah I showed physico-chemical (CD spectrum, molecular mass, HPLC elution), biochemical (amino-acid composition, sequence), immunochemical and pharmacological properties similar to those of the natural toxin. The synthetic toxin was recognized by a conformation-dependent monoclonal anti-Aah I antibody, with an IC50 value close to that for the natural toxin. Following intracerebroventricular injection, the synthetic and the natural toxins were similarly lethal to mice. In voltage-clamp experiments, Na(v) 1.2 sodium channel inactivation was inhibited by the application of sAah I or of the natural toxin in a similar way. This work describes a simple protocol for the chemical synthesis of a scorpion alpha-toxin, making it possible to produce structural analogues in time. 相似文献
37.
The effect of several biotic and abiotic factors on the fecundityand hatching success of Calanus helgolandicus was tested duringshort- and long-term incubations. The results show that thevariations of the reproductive responses of C.helgolandicusare time dependent and rely on the type of factor tested. Whenstandardized over a 24 h incubation period, estimates ofin situproduction and egg viability can be obtained with good accuracy. 相似文献
38.
Mohamed Benichou Gracia Martinez-Reina Felix Romojaro Jean-Claude Pech Alain Latché 《Physiologia plantarum》1995,94(4):629-634
A 36-kDa 1-aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase, which converts the ethylene precursor ACC into the conjugated derivative malonyl-ACC (MACC), has been isolated from etiolated mung bean ( Vigna radiata ) hypocotyls, and partially purified in a four-step procedure. The enzyme is stimulated about 7-fold by 100 m M K+ salts or 0.5 m M Co2+ salts, and is inhibited competitively by D-phenylalanine (Ki = 1.3 m M ) and non competitively by CoASH (0.3 m M ). Beside malonyl-CoA, it is capable to use succinyl-CoA as an acyl donor. The 36-kDa enzyme described here exhibits a lower optimum temperature (40°C) and a 7- or 3-fold lower apparent Km for ACC (68 μ M ) and malonyl-CoA (74 μ M ), respectively, when compared with its 55 kDa isoform already isolated from the same plant material. This data support the idea that several isoforms of ACC N-malonyltransferase exist in plants. These isoforms may play a differential role in regulating the availability of ACC, and consequently the rate of ethylene production, as well as detoxifying cells from D-amino acids. 相似文献
39.
Marc Jarry Mohamed Khaladi Martine Hossaert-McKey Doyle McKey 《Acta biotheoretica》1995,43(1-2):53-65
A model is proposed for the population dynamics of an annual plant (Sesbania vesicaria) with a seed bank (i.e. in which a proportion of seeds remain dormant for at least one year). A simple linear matrix model is deduced from the life cycle graph. The dominant eigenvalue of the projection matrix is estimated from demographic parameters derived from field studies. The estimated values for population growth rate () indicates that the study population should be experiencing a rapid exponential increase, but this was not the case in our population.The addition of density dependent effects on seedling survivorship and adult fecundity, effects for which field studies provide evidence, considerably improves our model. Depending on the demographic parameters, the model leads to stable equilibrium, oscillations, or chaos. Study of the behaviour of this model in the parameter space shows that the existence of a seed bank allows higher among-year variation of adult fecundity, without leaving the region of demographic stability. Field data obtained over 3 years confirm this prediction. 相似文献
40.
Nathalie Doerflinger Catherine Linder Karim Ouahchi Gabor Gyapay Jean Weissenbach Denis Le Paslier Philippe Rigault Samir Belal Christiane Ben Hamida Faycal Hentati Mongi Ben Hamida Massimo Pandolfo Stephano DiDonato Ronald Sokol Herbert Kayden Pierre Landrieu Alexandra Durr Alexis Brice Fran?oise Goutières Alfried Kohlschütter Pascal Sabouraud Ali Benomar Mohamed Yahyaoui Jean-Louis Mandel Michel Koenig 《American journal of human genetics》1995,56(5):1116-1124
Ataxia with vitamin E deficiency (AVED) is an autosomal recessive disease characterized clinically by neurological symptoms with often striking resemblance to those of Friedreich ataxia. This disorder has been reported previously as familial isolated vitamin E deficiency. We have mapped recently the AVED locus to a 5-cM confidence interval on chromosome 8q by homozygosity mapping in six Mediterranean families. We have now analyzed six new and two previously described families and demonstrate genetic homogeneity despite important clinical variability and wide geographic origins. Analysis of nine new tightly linked microsatellite markers, including four characterized in this study, revealed a predominant but not unique mutation in northern African populations, where this condition is more frequent. Haplotype analysis but also classical recombinations allowed us to refine the AVED position to a 1-cM interval. A YAC contig over this interval was constructed from marker STSs and YAC fingerprint data, in order to facilitate the search of the AVED gene. 相似文献