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91.
Cotton wool plaques (CWPs) are round lesions that lack a central amyloid core. CWPs have been observed in individuals affected by early-onset familial Alzheimer disease (FAD) associated with mutations in the presenilin 1 (PSEN1) gene. Here we present the characterization of the amyloid-beta (Abeta) peptides deposited in the brain of an individual affected by FAD carrying the novel missense (V261I) mutation in the PSEN1 gene. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry was used to determine the Abeta peptide species present in the cerebral and cerebellar cortices, in leptomeningeal vessels, and in CWPs isolated by laser microdissection (LMD). Our results indicate that amino-terminally truncated Abeta peptide species ending at residues 42 and 43 are the main Abeta peptides deposited in brain parenchyma and LMD-CWPs in association with the PSEN1 V261I mutation. Full-length Abeta1-42 and Abeta1-43 peptide species were underrepresented. CWPs were not found to be associated with vessels and did not contain Abeta1-40 peptides, the main component of the vascular deposits. Although Abeta deposits were present mostly in the form of CWPs in the cerebral cortex and as diffuse deposits in the cerebellar cortex, a similar array of amino-terminally truncated Abeta peptide species was seen in both cases. The biochemical data support the concept that parenchymal and vascular amyloid deposits are associated with a different array of Abeta peptide species. The generation and parenchymal deposition of highly insoluble amino-terminally truncated Abeta peptides may play an important role in the pathogenesis of AD and must be taken into consideration in developing new diagnostic and therapeutic strategies. 相似文献
92.
Javier Vargas-Villarreal Carlos Hernández-Luna Victor M. Torres de la Cruz Francisco González-Salazar Brenda Leticia Escobedo-Guajardo Salvador Said-Fernández 《Experimental parasitology》2010,125(4):394-399
Sphingomyelinase (SMase) activity was measured in Entamoeba histolytica particulate and soluble subcellular fractions. The effects on SMase of incubation time, total protein concentration, pH, and several divalent cations were determined. SMase-C and other unidentified esterase activity were detected in soluble and particulate fractions. SMase-C was 94.5-96.0% higher than the unidentified esterase activity. Soluble and insoluble SMase-C specific activities increased with protein dose and incubation time. Soluble and insoluble SMase-C activities were maximum at pH 7.5 and were dependent on Mg2+, Mn2+, or Co2+, and inhibited by Zn2+, Hg2+, Ca2+, and EDTA. SMase-C was active in the pH range of 3-10 and its maximum activity was at pH 7.5. The soluble and insoluble SMases have remarkably similar physicochemical properties, strongly suggesting that E. histolytica has just one isoform of neutral SMase-C that had not been described before and might be essential for E. histolytica metabolism or virulence. 相似文献
93.
González-Novo A Labrador L Jiménez A Sánchez-Pérez M Jiménez J 《Microbiology and immunology》2006,50(7):499-511
The relationship between the morphology and virulence of Candida albicans has aroused interest in the study of the proteins involved in its morphogenesis. We present virulence data for one important element in fungal morphogenesis-septins. We disrupted CaCDC10 and studied the virulence in a mouse infection model and the different steps followed by the fungus during the infection: adherence to epithelial cells, organ colonisation, macrophage phagocytosis, and host survival. We found the altered subcellular localisation of Int1--a C. albicans adhesin- in the septin null mutants. The Int1 mislocalisation and the defects in the cell wall of defective CaCdc10 strains permit us to propose a model for explaining the biological meaning of the absence of virulence presented by these septin mutants. 相似文献
94.
López-Diazguerrero NE López-Araiza H Conde-Perezprina JC Bucio L Cárdenas-Aguayo MC Ventura JL Covarrubias L Gutiérrez-Ruíz MC Zentella A Königsberg M 《Free radical biology & medicine》2006,40(7):1161-1169
Replicative senescence is a cellular response to stress that has been postulated to serve as a tumor suppression mechanism and a contributor to aging. Numerous experimental studies have demonstrated that an apparently identical senescent state can also be prematurely induced in vitro in different cell types following sublethal oxidative stress stimuli. The former suggests a molecular link between cell cycle regulation and cell survival that could involve regulatory proteins such as Bcl-2. There is strong evidence that, in addition to its well-known effects on apoptosis, Bcl-2 is involved in antioxidant protection and regulation of cell cycle progression. The aim of this work was to determine if the protection against oxidative stress mediated by Bcl-2 could prevent or delay oxidative stress-induced senescence. Using a retroviral infection system, Bcl-2 was overexpressed in primary, nonembryonic mice fibroblasts obtained from lungs derived from 2-month-old CD1 mice. Fibroblasts overexpressing Bcl-2 were exposed to 75 microM H2O2 for 2 h to induce SIPS. The rate of proliferation and the increment of senescent cells were then determined. Our results indicate that overexpression of Bcl-2 protected primary fibroblasts against oxidative stress-mediated reduction in cell proliferation, but did not prevent premature senescence. 相似文献
95.
Rodríguez-Canché LG Maldonado-Montiel TD Carrillo Navarro LA 《Revista de biología tropical》2006,54(4):1283-1293
Cysts of Artemia spp. collected from February 1997 to February 2000 in the Real de Salinas solar saltworks, Campeche, Mexico, were compared with Artemia franciscana (batch number 8,131 Microfeast Artemia Cysts, Texas, USA). The variables determined in these two populations were: number of cysts per gram, hatching percentage, hatching efficiency, hatching rate, hatching synchrony and hatching biomass, as well as diameter of the cysts and length of the nauplii (instar I). For Salinas, the average diameters of the encapsulated and decapsulated cysts were 230.5 +/- 4.14 and 221.8 +/- 3.39 microm, respectively. The thickness of the cyst shell was 4.35 +/- 0.68 microm and the length of the nauplii was 388.11 +/- 4.39 microm, this last value is among the smallest reported in the literature. For the commercial population of A. franciscana, the average diameters of the encapsulated and decapsulated cysts were 230.21 +/- 12.49 and 216.96 +/- 13.71, respectively. With respect to the corion thickness and length of the nauplii the values were 6.62 +/- 2.72 and 424.70 +/- 30.08, respectively. The protein value of the cysts (47.91 %) and nauplii (50.5 %) of Artemia population from Real de Salinas, are considered adequate to be used as food in aquaculture. The results indicate that the population from Real de Salinas presents positive features for its use in aquaculture in the region. 相似文献
96.
López-Arenas L Solís-Mendiola S Padilla-Zúñiga J Hernández-Arana A 《Biochimica et biophysica acta》2006,1764(7):1260-1267
We studied the effect of three electrolytes (LiCl, Na(2)SO(4), GuHCl) on the unfolding reaction of chymopapain, a two-domain protein belonging in the papain family of cysteine proteinases. Due to methodological reasons, these studies were carried out at pH 1.5 where the protein unfolds following biphasic kinetics. We have observed the presence of two different effects of electrolyte concentration on the unfolding reactions. At low ionic strength, the ionic atmosphere brought about an increase in reaction rates, regardless of the type of ions being present; this effect is attributed to a general "electrostatic screening" of charge-charge interactions in the macromolecule. At high ionic strength, each electrolyte exerted a distinctively different effect: both rate constants were largely increased by GuHCl (a well-known protein denaturant), but only slightly by LiCl; in contrast, Na(2)SO(4) (a good precipitant) decreased the value of both unfolding rates. These ion-specific (Hofmeister) effects were further used to estimate changes in accessible surface area (DeltaASA) upon formation of the transition states (TS) for unfolding. Results obtained with LiCl and Na(2)SO(4), which we analyzed by means of a parameterization derived from published solubility data of amino acid derivatives, are consistent with DeltaASA increments (for each phase) of about 8.0% of the total theoretical DeltaASA for complete unfolding of the chymopapain molecule. Results in the presence of GuHCl, which were analyzed by using a previous parameterization of protein unfolding data, gave larger DeltaASAs of activation, equivalent to 13 and 16% of the total unfolding DeltaASA. 相似文献
97.
New tricks of an old pattern: structural versatility of scorpion toxins with common cysteine spacing
Saucedo AL Flores-Solis D Rodríguez de la Vega RC Ramírez-Cordero B Hernández-López R Cano-Sánchez P Noriega Navarro R García-Valdés J Coronas-Valderrama F de Roodt A Brieba LG Domingos Possani L del Río-Portilla F 《The Journal of biological chemistry》2012,287(15):12321-12330
Scorpion venoms are a rich source of K(+) channel-blocking peptides. For the most part, they are structurally related small disulfide-rich proteins containing a conserved pattern of six cysteines that is assumed to dictate their common three-dimensional folding. In the conventional pattern, two disulfide bridges connect an α-helical segment to the C-terminal strand of a double- or triple-stranded β-sheet, conforming a cystine-stabilized α/β scaffold (CSα/β). Here we show that two K(+) channel-blocking peptides from Tityus scorpions conserve the cysteine spacing of common scorpion venom peptides but display an unconventional disulfide pattern, accompanied by a complete rearrangement of the secondary structure topology into a CS helix-loop-helix fold. Sequence and structural comparisons of the peptides adopting this novel fold suggest that it would be a new elaboration of the widespread CSα/β scaffold, thus revealing an unexpected structural versatility of these small disulfide-rich proteins. Acknowledgment of such versatility is important to understand how venom structural complexity emerged on a limited number of molecular scaffolds. 相似文献
98.
Rubio-Infante N Govea-Alonso DO Alpuche-Solís ÁG García-Hernández AL Soria-Guerra RE Paz-Maldonado LM Ilhuicatzi-Alvarado D Varona-Santos JT Verdín-Terán L Korban SS Moreno-Fierros L Rosales-Mendoza S 《Plant molecular biology》2012,78(4-5):337-349
Although the human immunodeficiency virus (HIV) causes one of the most important infectious diseases worldwide, attempts to develop an effective vaccine remain elusive. Designing recombinant proteins capable of eliciting significant and protective mammalian immune responses remain a priority. Moreover, large-scale production of proteins of interest at affordable cost remains a challenge for modern biotechnology. In this study, a synthetic gene encoding a C4V3 recombinant protein, known to induce systemic and mucosal immune responses in mammalian systems, has been introduced into tobacco chloroplasts to yield high levels of expression. Integration of the transgene into the tobacco plastome has been verified by Southern blot hybridization. The recombinant C4V3 protein is also detected in tobacco chloroplasts by confocal microscopy. Reactivity of the heterologous protein with both an anti-C4V3 rabbit serum as well as sera from HIV positive patients have been assayed using Western blots. When administered by the oral route in a four-weekly dose immunization scheme, the plant-derived C4V3 has elicited both systemic and mucosal antibody responses in BALB/c mice, as well as CD4+ T cell proliferation responses. These findings support the viability of using plant chloroplasts as biofactories for HIV candidate vaccines, and could serve as important vehicles for the development of a plant-based candidate vaccine against HIV. 相似文献
99.
Jiménez B Ugwu F Zhao R Ortí L Makhnevych T Pineda-Lucena A Houry WA 《The Journal of biological chemistry》2012,287(8):5698-5709
Tah1 and Pih1 are novel Hsp90 interactors. Tah1 acts as a cofactor of Hsp90 to stabilize Pih1. In yeast, Hsp90, Tah1, and Pih1 were found to form a complex that is required for ribosomal RNA processing through their effect on box C/D small nucleolar ribonucleoprotein assembly. Tah1 is a minimal tetratricopeptide repeat protein of 111 amino acid residues that binds to the C terminus of the Hsp90 molecular chaperone, whereas Pih1 consists of 344 residues of unknown fold. The NMR structure of Tah1 has been solved, and this structure shows the presence of two tetratricopeptide repeat motifs followed by a C helix and an unstructured region. The binding of Tah1 to Hsp90 is mediated by the EEVD C-terminal residues of Hsp90, which bind to a positively charged channel formed by Tah1. Five highly conserved residues, which form a two-carboxylate clamp that tightly interacts with the ultimate Asp-0 residue of the bound peptide, are also present in Tah1. Tah1 was found to bind to the C terminus of Pih1 through the C helix and the unstructured region. The C terminus of Pih1 destabilizes the protein in vitro and in vivo, whereas the binding of Tah1 to Pih1 allows for the formation of a stable complex. Based on our data, a model for an Hsp90-Tah1-Pih1 ternary complex is proposed. 相似文献
100.