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71.
Ebony Weems Ujjal K. Singha VaNae Hamilton Joseph T. Smith Karin Waegemann Dejana Mokranjac Minu Chaudhuri 《Eukaryotic cell》2015,14(3):286-296
Trypanosoma brucei, a parasitic protozoan that causes African trypanosomiasis, possesses a single member of the presequence and amino acid transporter (PRAT) protein family, which is referred to as TbTim17. In contrast, three homologous proteins, ScTim23, ScTim17, and ScTim22, are found in Saccharomyces cerevisiae and higher eukaryotes. Here, we show that TbTim17 cannot rescue Tim17, Tim23, or Tim22 mutants of S. cerevisiae. We expressed S. cerevisiae Tim23, Tim17, and Tim22 in T. brucei. These heterologous proteins were properly imported into mitochondria in the parasite. Further analysis revealed that although ScTim23 and ScTim17 were integrated into the mitochondrial inner membrane and assembled into a protein complex similar in size to TbTim17, only ScTim17 was stably associated with TbTim17. In contrast, ScTim22 existed as a protease-sensitive soluble protein in the T. brucei mitochondrion. In addition, the growth defect caused by TbTim17 knockdown in T. brucei was partially restored by the expression of ScTim17 but not by the expression of either ScTim23 or ScTim22, whereas the expression of TbTim17 fully complemented the growth defect caused by TbTim17 knockdown, as anticipated. Similar to the findings for cell growth, the defect in the import of mitochondrial proteins due to depletion of TbTim17 was in part restored by the expression of ScTim17 but was not complemented by the expression of either ScTim23 or ScTim22. Together, these results suggest that TbTim17 is divergent compared to ScTim23 but that its function is closer to that of ScTim17. In addition, ScTim22 could not be sorted properly in the T. brucei mitochondrion and thus failed to complement the function of TbTim17. 相似文献
72.
Albert M. Wu June H. Wu Tanuja Singh Biswajit Singha Dvora Sudakevitz Nechama Gilboa-Garber 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009
Ralstonia solanacearum lectin (RSL), that might be involved in phytopathogenicity, has been defined as lFuc?Man specific. However, the effects of polyvalency of glycotopes and mammalian structural units on binding have not been established. In this study, recognition factors of RSL were comprehensively examined with natural multivalent glycotopes and monomeric ligands using enzyme linked lectin-sorbent and inhibition assays. Among the glycans tested, RSL reacted strongly with multivalent blood group Ah (GalNAcα1–3[Fucα1–2]Gal) and H (Fucα1–2Gal) active glycotopes, followed by Bh (Galα1–3[Fucα1–2]Gal), Lea (Galβ1–3[Fucα1–4]GlcNAc) and Leb (Fucα1–2Galβ1–3[Fucα1–4]GlcNAc) active glycotopes. But weak or negligible binding was observed for blood group precursors having Galβ1–3/4GlcNAcβ1- (Iβ/IIβ) residues or Galβ1–3GalNAcα1- (Tα), GalNAcα1-Ser/Thr (Tn) bearing glycoproteins. These results indicate that the density and degree of exposure of multivalent ligands of α1–2 linked lFuc to Gal at the non-reducing end is the most critical factor for binding. An inhibition study with monomeric ligands revealed that the combining site of RSL should be of a groove type to fit trisaccharide binding with highest complementarity to blood group H trisaccharide (HL; Fucα1–2Galβ1–4Glc). The outstandingly broad RSL saccharide-binding profile might be related to the unusually wide spectrum of plants that suffer from R. solanacearum pathogenicity and provide ideas for protective antiadhesion strategies. 相似文献
73.
Singha H Mallick AI Jana C Isore DP Goswami TK Srivastava SK Azevedo VA Chaudhuri P Owais M 《Microbes and infection / Institut Pasteur》2008,10(10-11):1089-1096
In the present study, we evaluated prophylactic prospective of liposome based DNA vaccine co-expressing Cu-Zn superoxide dismutase (SOD) along with interleukin-18 (IL-18) against experimental murine brucellosis. The immunization schedule involves liposome-mediated delivery of pVsod (encoding SOD of Brucella abortus) and pVIL18-sod (encoding IL-18 of mouse and SOD of B. abortus) DNA constructs. The data highlight potential of Escherichia coli lipid liposome (escheriosome) based DNA delivery vehicle to induce SOD specific humoral and cellular immune responses in the immunized mice. The co-expression of SOD along with IL-18 ensued in higher lymphoproliferative response and IFN-gamma production in comparison to the group of animals that were immunized with free form of SOD-DNA. Antibody response developed upon immunization with both DNA vaccines was of IgG2a type mainly. The results of the present study show that co-expression of IL-18 along with SOD polarized the antigen specific immune responses toward Th-1 direction, a desirable feature to control intracellular pathogens. 相似文献
74.
75.
Singha NC Vlamis-Gardikas A Holmgren A 《The Journal of biological chemistry》2003,278(24):21421-21428
T7 phage DNA polymerase is a tight 1:1 complex of the gene 5 protein (g5p) (80 kDa) of phage T7 and thioredoxin (12 kDa) from the Escherichia coli host. The holoenzyme is essential for the replication of the phage. We estimated the real-time kinetics and thermodynamics of the interaction of g5p with thioredoxin (wild type and mutants) using surface plasmon resonance. Thioredoxin was immobilized on a CM5 sensor chip through a six-carbon spacer (6-amino-n-hexanoic acid) using standard amine coupling. Reduced thioredoxin bound g5p but oxidized thioredoxin did not. The association and dissociation phases of the complex fit a two-exponential model with an apparent equilibrium dissociation constant (KD) of 2.2 nm for thioredoxin with 4.7 x 104.M-1.s-1 and 10.5 x 10-5.s-1 as the corresponding association (ka) and dissociation (kd) rate constants. The strong binding of g5p to thioredoxin is therefore due to fast association and very slow dissociation, a situation similar to antigen-antibody interactions. Thioredoxin mutants P34S, D26A, K57M, D26A/K57M, W31F, W31Y, K36A, K36E, and Y49F had KD values in the range of 1 to 8 nm, whereas mutant W28A had a KD of 12.5 nm. No detectable interaction was observed for mutants P40G, W31H, W31A, and C35A. The effect of temperature on KD and the changes in enthalpy (-DeltaH = 20.2 kcal.m-1) and entropy (TDeltaS =-8.4 kcal.m-1) upon formation of the complex suggested that the interaction is driven by an increase in enthalpy and opposed by a decrease in entropy. 相似文献
76.
The winged bean (Psophocarpus tetragonolobus) agglutinin (total lectin) and its basic (WBA I) and acidic isoform (WBA II) were used to analyze capillaries in sections
from human muscle. The microvessels were clearly labeled after incubation with the lectins in both normal muscle and in old
muscles with age-related type II atrophy or muscle fiber grouping. Muscle fibers, nerves, and connective tissue remained unstained.
The total lectin detected muscle capillaries from all blood group AB0 individuals. The isoform WBA I reacted only with blood
vessels in blood group A and B individuals, while the blood vessels in blood group 0 individuals were demonstrated with WBA
II. WBA I staining was inhibited by p-nitrophenyl α-galactopyranoside and N-acetylgalactosamine, whereas 2′-fucosyllactose and preincubation with an antibody against type-1 chain H abolished capillary
staining with WBA II. The study demonstrates the usefulness of WBA as a marker of capillaries in human muscle.
Accepted: 2 September 1996 相似文献
77.
Changes in nutrient composition and pH of the culture medium during in vitro shoot proliferation of crabapple and pear 总被引:5,自引:0,他引:5
Suman Singha Gene H. Oberly Edwin C. Townsend 《Plant Cell, Tissue and Organ Culture》1987,10(3):209-220
Immature soybean (Glycine max (L.) Merr) embryos, or cotyledons isolated from them, were cultured on modified MS medium containing B5 vitamins and NAA (50 M) to induce somatic embryogenesis. The effects of media variables, dissection treatments and light conditions were investigated in this system. The efficiency of embryogenesis increased as sugar concentration decreased from 12 to 1.5%; sucrose and glucose were similarly effective as carbon sources. In an examination of the effects of medium pH, values between pH 5.0 and 7.0 gave similar embryogenesis efficiencies, but the frequency of normal embryos was greater in media with low pH values. In buffered medium (10 mM MES), a pH of 5.0 was inhibitory to embryogenesis, and most normal embryos were produced at pH 5.5. Under various dissection treatments, embryogenesis efficiency and root and callus production were increased by tissue damage. Somatic embryogenesis was observed both in darkness and in light, although embryo development was impaired under high light (80 E m-2 s-1) conditions. The ability of somatic embryos to germinate was closely correlated with embryo normality, and was influenced little by the hormone content of germination media. Of various media tested for their ability to support the growth of germinated embryos, a medium based on hydroponic nutrient salts, supplemented with yeast extract, and gelled with Difco-Bacto agar gave the best plantlet growth.Abbreviations E m-2 s-1
microEinsteins per square meter per second
- NAA
-napthalene acetic acid
- N50
MS salts with B5 vitamins and 50 M NAA (Napthalene acetic acid)
- MES
2(n-morpholino) ethanesulphuric acid
- BAP
benzylamino purine
- IBA
indole butyric acid
This paper (No. 86-3-97) is published with the approval of the director of the Kentucky Agricultural Experiment Station. 相似文献
78.
This review will cover the current strategies that are being adopted to efficiently deliver small interfering RNA using nonviral vectors, including the use of polymers such as polyethylenimine, poly(lactic-co-glycolic acid), polypeptides, chitosan, cyclodextrin, dendrimers, and polymers-containing different nanoparticles. The article will provide a brief and concise account of underlying principle of these polymeric vectors and their structural and functional modifications which were intended to serve different purposes to affect efficient therapeutic outcome of small-interfering RNA delivery. The modifications of these polymeric vectors will be discussed with reference to stimuli-responsiveness, target specific delivery, and incorporation of nanoconstructs such as carbon nanotubes, gold nanoparticles, and silica nanoparticles. The emergence of small-interfering RNA as the potential therapeutic agent and its mode of action will also be mentioned in a nutshell. 相似文献
79.
80.
Source-Sink Relationship: Control of Photosynthesis in the Flag Leaf by the Panicle in Wheat 总被引:2,自引:0,他引:2
If the sink organs regulate the metabolic activity of the sourceorgans through the transmission of a signal and that signalis chemical in nature, then it should be present among the substancescoming out of the panicle. When flag leaf respiration and photosynthesisof wheat (Tritcum aestivum L.) cv. HP 1459 were measured withan infrared gas analyser after feeding the flag leaves withthe diffusate coming out of the panicle, it was observed thatwhile respiration was unaffected, photosynthesis was sharplyinhibited; the inhibition decreased with increasing age of thepanicle. Among the known plant growth regulators none couldsatisfy the requirements of this role with the exception ofabscisic acid which was found to inhibit photosynthesis by morethan 50% even at 107 M, when respiration was affectedby only 8%. Apparently, abscisic acid inhibited photosynthesisthrough its effects on stomatal movement. (Received September 2, 1986; Accepted May 1, 1987) 相似文献