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21.
Protein D2 channel of the Pseudomonas aeruginosa outer membrane has a binding site for basic amino acids and peptides 总被引:19,自引:0,他引:19
Protein D2 of Pseudomonas aeruginosa outer membrane is known to facilitate the specific permeation of imipenem (N-formimdoylthienamycin) across this membrane barrier. We have characterized the binding site in the protein D2 channel by studying the competitive inhibition, by various solutes, of imipenem diffusion into the periplasm. We found that basic amino acids, lysine, arginine, histidine, and ornithine, were effective inhibitors. L- and D-lysine were found to be competitive inhibitors with approximate Ki values of 0.6 and 0.3 mM, respectively. Peptides containing L-lysine at the carboxyl terminus, as well as dipeptides containing L-lysine at the amino terminus, were also able to inhibit the transport. Wild type cells transported tripeptide Thr-Ser-Lys into the periplasm three to four times as rapidly as the mutant cells lacking the D2 protein. These results suggest that protein D2 plays a physiologically significant role in the uptake of basic amino acids and peptides containing these amino acids across the outer membrane of P. aeruginosa. 相似文献
22.
Jose O Leite Ushma Vaishnav Michael Puglisi Heather Fraser Joaquim Trias Maria Luz Fernandez 《BMC cardiovascular disorders》2009,9(1):1-9
Background
High blood pressure (BP) is now an important public health problem in non-industrialised countries. The limited evidence suggests ethnic inequalities in BP in adults in some non-industrialised countries. However, it is unclear whether these ethnic inequalities in BP patterns in adults reflect on adolescents. Hence, we assessed ethnic differences in BP, and the association of BP with body mass index (BMI) among adolescents aged 12–17 years in Paramaribo, Suriname.Methods
Cross-sectional study with anthropometric and blood pressure measurements. A random sample of 855 adolescents (167 Hindustanis, 169 Creoles, 128 Javanese, 91 Maroons and 300 mixed-ethnicities) were studied. Ethnicity was based on self-reported ethnic origin.Results
Among boys, Maroons had a lower age- and height-adjusted systolic BP than Creoles, and a lower diastolic BP than other ethnic groups. However, after further adjustment for BMI, only diastolic BP in Maroons was significantly lower than in Javanese (67.1 versus 70.9 mmHg). Creole boys had a lower diastolic BP than Hindustani (67.3 versus 70.2 mmHg) and Javanese boys after adjustment for age, height and BMI. Among girls, there were no significant differences in systolic BP between the ethnic groups. Maroon girls, however, had a lower diastolic BP (65.6 mmHg) than Hindustani (69.1 mmHg), Javanese (71.2 mmHg) and Mixed-ethnic (68.3 mmHg) girls, but only after differences in BMI had been adjusted for. Javanese had a higher diastolic BP than Creoles (71.2 versus 66.8 mmHg) and Mixed-ethnicity girls. BMI was positively associated with BP in all the ethnic groups, except for diastolic BP in Maroon girls.Conclusion
The study findings indicate higher mean BP levels among Javanese and Hindustani adolescents compared with their African descent peers. These findings contrast the relatively low BP reported in Javanese and Hindustani adult populations in Suriname and underscore the need for public health measures early in life to prevent high BP and its sequelae in later life. 相似文献23.
Trias Astériou Jean-Claude Vincent Frédéric Tranchepain Brigitte Deschrevel 《Matrix biology》2006,25(3):166-174
Hyaluronidase and high levels of hyaluronan are found together in tumours. It is highly likely that hyaluronidase activity controls the balance between high molecular mass hyaluronan and oligosaccharides, and thus plays an important role in cancer development. The hyaluronan hydrolysis catalysed by bovine testicular hyaluronidase was studied as a model. The kinetics was investigated at pH 5 and 37 degrees C using the colorimetric N-acetyl-d-glucosamine reducing end assay method. While the substrate dependence obtained in the presence of 0.15 mol L(-1) ionic strength exhibited a Michaelis-Menten behaviour, an atypical behaviour was observed under low ionic strength: for increasing hyaluronan concentrations, the initial reaction rate increased, reached a maximum and then decreased to a very low level, close to zero at high substrate concentrations. One of the various hypotheses examined to explain this atypical behaviour is the formation of non-specific complexes between hyaluronan and hyaluronidase based on electrostatic interactions. This hypothesis is the only one that can explain all the experimental results including the variation of the reaction medium turbidity as a function of time and the influence on the initial reaction rate of the hyaluronan concentration over hyaluronidase concentration. However, phenomena such as the high viscosity of highly concentrated hyaluronan solutions or the steric exclusion of hyaluronidase from hyaluronan solutions may contribute to the atypical behaviour. Finally, the biological implications of the non-linear and non-monotonous shape of the hyaluronan-hyaluronidase substrate dependence in the regulation of the hyaluronan chain molecular mass are discussed, in particular in the case of cancer development. 相似文献
24.
Katerina E. Tsitsanou Christina E. Drakou Trias Thireou Anna Vitlin Gruber Georgia Kythreoti Abdussalam Azem Dimitrios Fessas Elias Eliopoulos Kostas Iatrou Spyros E. Zographos 《The Journal of biological chemistry》2013,288(46):33427-33438
Much physiological and behavioral evidence has been provided suggesting that insect odorant-binding proteins (OBPs) are indispensable for odorant recognition and thus are appealing targets for structure-based discovery and design of novel host-seeking disruptors. Despite the fact that more than 60 putative OBP-encoding genes have been identified in the malaria vector Anopheles gambiae, the crystal structures of only six of them are known. It is therefore clear that OBP structure determination constitutes the bottleneck for structure-based approaches to mosquito repellent/attractant discovery. Here, we describe the three-dimensional structure of an A. gambiae “Plus-C” group OBP (AgamOBP48), which exhibits the second highest expression levels in female antennae. This structure represents the first example of a three-dimensional domain-swapped dimer in dipteran species. A combined binding site is formed at the dimer interface by equal contribution of each monomer. Structural comparisons with the monomeric AgamOBP47 revealed that the major structural difference between the two Plus-C proteins localizes in their N- and C-terminal regions, and their concerted conformational change may account for monomer-swapped dimer conversion and furthermore the formation of novel binding pockets. Using a combination of gel filtration chromatography, differential scanning calorimetry, and analytical ultracentrifugation, we demonstrate the AgamOBP48 dimerization in solution. Eventually, molecular modeling calculations were used to predict the binding mode of the most potent synthetic ligand of AgamOBP48 known so far, discovered by ligand- and structure-based virtual screening. The structure-aided identification of multiple OBP binders represents a powerful tool to be employed in the effort to control transmission of the vector-borne diseases. 相似文献
25.
Trias R Ruiz-Rueda O García-Lledó A Vilar-Sanz A López-Flores R Quintana XD Hallin S Bañeras L 《Applied and environmental microbiology》2012,78(17):6352-6356
Ammonia-oxidizing bacteria (AOB) and archaea (AOA) were quantified in the sediments and roots of dominant macrophytes in eight neutral to alkaline coastal wetlands. The AOA dominated in most samples, but the bacterial-to-archaeal amoA gene ratios increased with increasing ammonium levels and pH in the sediments. For all plant species, the ratios increased on the root surface relative to the adjacent bulk sediment. This suggests that root surfaces in these environments provide conditions favoring enrichment of AOB. 相似文献
26.
Asteriou T Deschrevel B Delpech B Bertrand P Bultelle F Merai C Vincent JC 《Analytical biochemistry》2001,293(1):53-59
Hyaluronan concentration and hyaluronidase activity can be assayed by using different techniques including turbidimetry, viscosimetry, ELISA, chromatography, and colorimetry. The most popular colorimetric method is that of J. Reissig et al. (1955, J. Biol. Chem. 217, 959-966), in which the color results from a reaction between the Ehrlich's reagent (DMAB) and the N-acetyl-d-glucosamine reducing end of each hyaluronan chain. Nevertheless, there are problems with this method when proteins are present in the medium. Here we propose a new interpretation of the Reissig signal for estimating such reducing ends in media containing enzymes or other proteins. This interpretation is based on the fact that the absorbance obtained by using the Reissig method results from two factors: a turbidity due to the formation of polysaccharide-protein complexes and a color resulting from the action of DMAB on the reducing end of the polysaccharide chains. The turbidity at 585 nm, the wavelength at which the color intensity is maximal, may be estimated by curve fitting the spectrum between 450 and 650 nm. Subtracting the turbidity from the absorbance gives the colorimetric intensity which represents the concentration of polysaccharide chains. Moreover, the turbidity may give additional information about the existence of polysaccharide-protein complexes and their nature. 相似文献
27.
Jain R Sundram A Lopez S Neckermann G Wu C Hackbarth C Chen D Wang W Ryder NS Weidmann B Patel D Trias J White R Yuan Z 《Bioorganic & medicinal chemistry letters》2003,13(23):4223-4228
We report the synthesis and biological activity of analogues of VRC3375 (N-hydroxy-3-R-butyl-3-[(2-S-(tert-butoxycarbonyl)-pyrrolidin-1-ylcarbonyl]propionamide), an orally active peptide deformylase inhibitor. This study explores the structure-activity relationship of various chelator groups, alpha substituents, P(2)' and P(3)' substituents in order to achieve optimal antibacterial activity with minimal toxicity liability. 相似文献
28.
Thireou T Reczko M 《IEEE/ACM transactions on computational biology and bioinformatics / IEEE, ACM》2007,4(3):441-446
An algorithm called bidirectional long short-term memory networks (BLSTM) for processing sequential data is introduced. This supervised learning method trains a special recurrent neural network to use very long-range symmetric sequence context using a combination of nonlinear processing elements and linear feedback loops for storing long-range context. The algorithm is applied to the sequence-based prediction of protein localization and predicts 93.3 percent novel nonplant proteins and 88.4 percent novel plant proteins correctly, which is an improvement over feedforward and standard recurrent networks solving the same problem. The BLSTM system is available as a Web service at http://stepc.stepc.gr/-synaptic/blstm.html. 相似文献
29.
Patricia Alamo Alberto Gallardo Miguel A. Pavón Isolda Casanova Manuel Trias Maria A. Mangues Esther Vázquez Antonio Villaverde Ramon Mangues Maria V. Céspedes 《Disease models & mechanisms》2014,7(3):387-396
Mouse colorectal cancer (CRC) models generated by orthotopic microinjection of human CRC cell lines reproduce the pattern of lymphatic, haematological and transcoelomic spread but generate low metastatic efficiency. Our aim was to develop a new strategy that could increase the metastatic efficiency of these models. We used subcutaneous implantation of the human CRC cell lines HCT116 or SW48 prior to their orthotopic microinjection in the cecum of nude mice (SC+ORT). This subcutaneous preconditioning significantly enhanced metastatic dissemination. In the HCT116 model it increased the number and size of metastatic foci in lymph nodes, lung, liver and peritoneum, whereas, in the SW48 model, it induced a shift from non-metastatic to metastatic. In both models the number of apoptotic bodies in the primary tumour in the SC+ORT group was significantly reduced compared with that in the direct orthotopic injection (ORT) group. Moreover, in HCT116 tumours the number of keratin-positive tumour buddings and single epithelial cells increased at the invasion front in SC+ORT mice. In the SW48 tumour model, we observed a trend towards a higher number of tumour buds and single cells in the SC+ORT group but this did not reach statistical significance. At a molecular level, the enhanced metastatic efficiency observed in the HCT116 SC+ORT model was associated with an increase in AKT activation, VEGF-A overexpression and downregulation of β1 integrin in primary tumour tissue, whereas, in SW48 SC+ORT mice, the level of expression of these proteins remained unchanged. In summary, subcutaneous preconditioning increased the metastatic dissemination of both orthotopic CRC models by increasing tumour cell survival and invasion at the tumour invasion front. This approach could be useful to simultaneously study the mechanisms of metastases and to evaluate anti-metastatic drugs against CRC.KEY WORDS: Collective invasion, Colorectal cancer model, Metastasis, Orthotopic injection, Single tumour cell, Subcutaneous preconditioning 相似文献
30.