共查询到20条相似文献,搜索用时 15 毫秒
1.
Ghosh S Bandyopadhyay S Mukherjee K Mallick A Pal S Mandal C Bhattacharya DK Mandal C 《Glycoconjugate journal》2007,24(1):17-24
Exploiting the selective affinity of Achatinin-H towards 9-O-acetylneuraminic acid(α2-6)GalNAc, we have demonstrated the presence of 9-O-acetylated sialoglycoproteins (Neu5,9Ac2-GPs) on hematopoietic cells of children suffering from acute lymphoblastic leukemia (ALL), indicative of defective sialylation
associated with this disease. The carbohydrate epitope of Neu5,9Ac2-GPsALL was confirmed by using several synthetic sialic acid analogues. They are functionally active signaling molecules as demonstrated
by their role in mediating lymphoproliferative responses and consequential increased production of IFN-γ due to specific stimulation
of Neu5,9Ac2-GPs on PBMCALL with Achatinin-H. Cells devoid of 9-O-acetylations (9-O-AcSA−) revealed decreased nitric oxide production as compared to 9-O-AcSA+ cells on exposure to IFN-γ. Under this condition, a decrease in viability of 9-O-AcSA− cells as compared to 9-O-AcSA+ cells was also observed which was reflected from increased caspase 3 activity and apoptosis suggesting the protective role
of this glycotope. These Neu5,9Ac2-GPs are also capable of inducing disease-specific anti-Neu5,9Ac2-GPs antibodies in ALL children. Additionally, we have observed that disease-specific anti-Neu5,9Ac2-GPs have altered glycosylation profile, and they are incapable of exerting a few Fc-glycosylation-sensitive effector functions.
These observations hint toward a disbalanced homeostasis, thereby enabling the cancer cells to escape host defense. Taken
together, it may be hypothesized that Neu5,9Ac2-GPs and their antibodies play a prominent role in promoting the survival of lymphoblasts in ALL. 相似文献
2.
Sialate-O-acetylesterase was purified almost 900-fold from particle-free supernatants of horse liver by gel filtration, ion-exchange
chromatography and isoelectric focussing. The native enzyme on gel filtration exhibits a molecular weight of 54,000 Da. It
was separated by isoelectric focussing into two forms with pI values of 4.8 and 5.7, respectively. The esterase with a lower pI hydrolyses only 9-O-acetyl groups from sialic acids (KM 1.1 mM), while that with the higher pI esterifies both 4- and 9-O-acetylated monosaccharides at similar rates (KM 0.3 M and 1.3 mM, respectively). Both forms are inactive with 7-O-acetylated N-acetylneuraminic acid. Enzyme assays were carried out at the pH optimum (pH 8.4–8.6) using free O-acetylated sialic acids followed by direct analysis of the reaction products by isocratic anion-exchange HPLC. Glycosidically
bound sialic acids can also be de-O-acetylated. Horse liver esterase seems to be an essential enzyme for the catabolism of 4-O-acetylated sialoglycoconjugates, since sialidase from this tissue cannot act on 4-O-acetylated sialic acids. 相似文献
3.
Ohsato S Ochiai-Fukuda T Nishiuchi T Takahashi-Ando N Koizumi S Hamamoto H Kudo T Yamaguchi I Kimura M 《Plant cell reports》2007,26(4):531-538
Fusarium head blight (FHB) is a devastating disease of small grain cereal crops caused by the necrotrophic pathogen Fusarium graminearum and Fusarium culmorum. These fungi produce the trichothecene mycotoxin deoxynivalenol (DON) and its derivatives, which enhance the disease development
during their interactions with host plants. For the self-protection, the trichothecene producer Fusarium species have Tri101 encoding trichothecene 3-O-acetyltransferase. Although transgenic expression of Tri101 significantly reduced inhibitory action of DON on tobacco plants, there are several conflicting observations regarding the
phytotoxicity of 3-acetyldeoxynivalenol (3-ADON) to cereal plants; 3-ADON was reported to be highly phytotoxic to wheat at
low concentrations. To examine whether cereal plants show sufficient resistance to 3-ADON, we generated transgenic rice plants
with stable expression and inheritance of Tri101. While root growth of wild-type rice plants was severely inhibited by DON in the medium, this fungal toxin was not phytotoxic
to the transgenic lines that showed trichothecene 3-O-acetylation activity. This is the first report demonstrating the DON acetylase activity and DON-resistant phenotype of cereal
plants expressing the fungal gene.
S. Ohsato and T. Ochiai-Fukuda should be considered as joint first authors. 相似文献
4.
Pal S Chatterjee M Bhattacharya DK Bandhyopadhyay S Mandal C Mandal C 《Glycoconjugate journal》2001,18(7):529-537
Initial studies have revealed an enhanced surface expression of O-acetylated sialoglycoconjugates (O-AcSGs) on lymphoblasts concomitant with high titres of IgG in childhood Acute Lymphoblastic Leukaemia (ALL) (Mandal C, Chatterjee M, Sinha D, Br J Haematol 110, 801–12, 2000). In our efforts to identify disease specific markers for ALL, we have affinity-purified IgM directed against O-AcSGs that reacts with three disease specific O-AcSGs present on membrane proteins derived from peripheral blood mononuclear cells (PBMC) of ALL patients. Antibody specificity towards O-AcSGs was confirmed by selective binding to erythrocytes bearing surface O-AcSGs, decreased binding with de-O-acetylated BSM and following pretreatment with O-acetyl esterase. Competitive inhibition ELISA demonstrated a higher avidity of IgM for O-AcSG than IgG. Flow cytometry demonstrated the diagnostic potential of purified O-AcSA IgM as binding was specific with ALL patients and minimal with other haematological disorders and normal individuals. It therefore may be adopted as a non-invasive approach for detection of childhood ALL. Taken together, the data indicates that carbohydrate epitopes having terminal O-AcSA 2 6 GalNAc determinants induce disease specific IgG and IgM, potentially useful molecular markers for childhood ALL. 相似文献
5.
Ghosh S Bandyopadhyay S Mallick A Pal S Vlasak R Bhattacharya DK Mandal C 《Journal of cellular biochemistry》2005,95(1):206-216
An enhanced linkage-specific 9-O-acetylated sialic acid (9-O-AcSA) on peripheral blood mononuclear cells (PBMC) of children with acute lymphoblastic leukaemia, ALL (PBMC(ALL), 9-O-AcSA+ cells) was demonstrated by using a lectin, Achatinin-H, whose lectinogenic epitope was 9-O-AcSAalpha2-6GalNAc. Our aim was to evaluate the in vitro contributory role of this glycotope (9-O-AcSAalpha2-6GalNAc) towards the survival of these 9-O-AcSA+ cells in ALL patients. For direct comparison, 9-O-AcSA- cells were generated by removing O-acetyl group of 9-O-AcSA present on PBMC(ALL) using O-acetyl esterase. An elevated level of serum interferon gamma (IFN-gamma) in affected children led us to think that PBMC(ALL) are continuously exposed specifically to this cytokine. Accordingly, 9-O-AcSA+ and 9-O-AcSA- cells were exposed in vitro to IFN-gamma. A twofold increased NO release along with inducible NO synthase (iNOS) mRNA expression by the 9-O-AcSA+ cells was observed as compared to the 9-O-AcSA- cells. The decreased viability of IFN-gamma exposed 9-O-AcSA- cells as compared to 9-O-AcSA+ cells were reflected from a 5.0-fold increased caspase-3-like activity and a 10.0-fold increased apoptosis in the 9-O-AcSA- cells when production of NO was lowered by adding competitive inhibitor of iNOS in reaction mixture. Therefore, it may be envisaged that a link exists between induction of this glycotope and their role in regulating viability of PBMC(ALL). Taken together, it is reasonable to hypothesise that O-acetylation of sialic acids on PBMC(ALL) may be an additional mechanism that promotes the survival of lymphoblasts by avoiding apoptosis via IFN-gamma-induced NO production. 相似文献
6.
We isolated several mutants of Arabidopsis thaliana (L.) Heynh. that accumulated less anthocyanin in the plant tissues, but had seeds with a brown color similar to the wild-type.
These mutants were allelic with the anthocyaninless1 (anl1) mutant that has been mapped at 15.0 cM of chromosome 5. We performed fine mapping of the anl1 locus and determined that ANL1 is located between the nga106 marker and a marker corresponding to the MKP11 clone. About 70 genes are located between these
two markers, including three UDP-glucose:flavonoid-3-O-glucosyltransferase-like genes and a glutathione transferase gene (TT19). A mutant of one of the glucosyltransferase genes (At5g17050) was unable to complement the anl1 phenotype, showing that the ANL1 gene encodes UDP-glucose:flavonoid-3-O-glucosyltransferase. ANL1 was expressed in all tissues examined, including rosette leaves, stems, flower buds and roots. ANL1 was not regulated by TTG1. 相似文献
7.
Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. Oxidative cleavage of cis-epoxycarotenoids catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED) is the main regulatory step in the biosynthesis of ABA in higher plants. A NCED gene, SgNCED1, was cloned from the dehydrated leaves of Stylosanthes guianensis. The 2,241-bp full-length SgNCED1 had a 1,809-bp ORF, which encodes a peptide of 602 amino acids. The deduced amino acid sequence of SgNCED1 protein shared
high identity with other NCEDs. At the N-terminus of the SgNCED1 located a chloroplast transit peptide sequence. DNA blot
analysis revealed that SgNCED1 was a single copy gene in the genome of S. guianensis. The relationship between expression of SgNCED1 and endogenous ABA level was investigated. The expression of SgNCED1 was induced in both leaves and roots of S. guianensis under drought stress. Dehydration and salt stress induced the expression of SgNCED1 strongly and rapidly. The ABA accumulation was coincidently induced with the SgNCED1 mRNA under drought, dehydration and salt stress. The expression of SgNCED1 and ABA accumulation were also induced under chilling condition. 相似文献
8.
Rauschenbach IY Adonyeva NV Alekseev AA Chentsova NA Gruntenko NE 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2008,178(3):315-320
The effect of 20-hydroxyecdysone (20E) and the juvenile hormone (JH) on the activity of the arylalkylamine N-acetyltransferase (AANAT) was studied in young females of wild-type D. virilis and D. melanogaster. 20E feeding of the flies led to a decrease in AANAT activity in both species when dopamine (DA) was used as substrate, but
did not affect the enzyme activity when octopamine (OA) was used as substrate. JH application increased AANAT activity with
DA as substrate in both species, but did not change it with OA as substrate. AANAT activity was also measured in young females
of a JH-deficient strain of D. melanogaster, apterous
56f
. A decrease in the enzyme activity was observed in the mutant females as compared to wild-type. Mechanisms of regulation
of DA level by gonadotropins in Drosophila are discussed. 相似文献
9.
Dehennaut V Lefebvre T Leroy Y Vilain JP Michalski JC Bodart JF 《Glycoconjugate journal》2009,26(3):301-311
Little is known about the impact of O-linked-N-acetylglucosaminylation (O-GlcNAc) in gametes production and developmental processes. Here we investigated changes in O-GlcNAc, UDP-GlcNAc and O-GlcNAc transferase (OGT) levels in Xenopus laevis from oogenesis to embryo hatching. We showed that in comparison to stage VI, stages I–V oocytes expressed higher levels of
O-GlcNAc correlating changes in OGT expression, but not in UDP-GlcNAc pools. Upon progesterone stimulation, an O-GlcNAc level burst occurred during meiotic resumption long before MPF and Mos-Erk2 pathways activations. Finally, we observed
high levels of O-GlcNAc, UDP-GlcNAc and OGT during segmentation that decreased concomitantly at the onset of gastrulation. Nevertheless, no
correlation between the glycosylation, the nucleotide-sugar and the glycosyltransferase was observed after neurulation. Our
results show that O-GlcNAc is regulated throughout oogenesis and development within a complex pattern and suggest that dysfunctions in the dynamics
of this glycosylation could lead to developmental abnormalities. 相似文献
10.
Melhorn V Matsumi K Koiwai H Ikegami K Okamoto M Nambara E Bittner F Koshiba T 《Journal of plant research》2008,121(1):125-131
Abscisic acid (ABA) regulates stomatal closure in response to water loss. Here, we examined the competence of guard cells
to synthesize ABA, using two Arabidopsis ABA biosynthetic enzymes. 35S pro::AtNCED3-GFP and AAO3-GFP were introduced into guard cells of broad bean leaves. AtNCED3-GFP expression was detected at the chloroplasts, whereas green
fluorescent protein (GFP) and AAO3-GFP were in the cytosol. The stomatal aperture was decreased in AtNCED3-GFP- and AAO3-GFP-transformed guard cells. This indicated that ABA biosynthesis is stimulated by heterologous expression of AtNCED3 and Arabidopsis
aldehyde oxidase 3 (AAO3) proteins, which both seem to be regulatory enzymes for ABA biosynthesis in these cells. Furthermore,
stomatal closure by the expression of AtNCED3 and AAO3 suggested that the substrates of the enzymes are present and native
ABA-biosynthesis enzymes are active in guard cells.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
V. Melhorn and K. Matsumi contributed equally to this work. 相似文献
11.
Stefanie Kimbacher Ingrid Gerstl Branko Velimirov Sylvia Hagemann 《Molecular genetics and genomics : MGG》2009,282(2):165-172
P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding
region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
A biochemical investigation of arabinogalactan proteins (AGPs) in Physcomitrella
patens was undertaken with particular emphasis on the glycan chains. Following homogenization and differential centrifugation of
moss gametophytes, AGPs were obtained by Yariv phenylglycoside-induced precipitation from the soluble, microsomal membrane,
and cell wall fractions. Crossed-electrophoresis indicated that each of these three AGP fractions was a mixture of several
AGPs. The soluble AGP fraction was selected for further separation by anion-exchange and gel-permeation chromatography. The
latter indicated molecular masses of ∼100 and 224 kDa for the two major soluble AGP subfractions. The AGPs in both of these
subfractions contained the abundant (1,3,6)-linked galactopyranosyl residues, terminal arabinofuranosyl residues, and (1,4)-linked
glucuronopyranosyl residues that are typical of many angiosperm AGPs. Unexpectedly, however, the moss AGP glycan chains contained
about 15 mol% terminal 3-O-methyl-l-rhamnosyl residues, which have not been found in angiosperm AGPs. This unusual and relatively nonpolar sugar, also called
l-acofriose, is likely to have considerable effects on the overall polarity of Physcomitrella AGPs. A review of the literature indicates that the capacity to synthesize polymers containing 3-O-methyl-l-rhamnosyl residues is present in a variety of bacteria, algae and lower land plants but became less common through evolution
to the extent that this sugar has been found in only a few species of angiosperms where it occurs as a single residue on steroidal
glycosides. 相似文献
13.
14.
Two uvrA-like genes, designated uvrA1 and uvrA2, that may be involved in nucleotide excision repair in Xanthomonas axonopodis pv. citri (X. a. pv. citri) strain XW47 were characterized. The uvrA1 gene was found to be 2,964 bp in length capable of encoding a protein of 987 amino acids. The uvrA2 gene was determined to be 2,529 bp with a coding potential of 842 amino acids. These two proteins share 71 and 39% identity,
respectively, in amino acid sequence with the UvrA protein of Escherichia coli. Analyses of the deduced amino acid sequence revealed that UvrA1 and UvrA2 have structures characteristic of UvrA proteins,
including the Walker A and Walker B motifs, zinc finger DNA binding domains, and helix-turn-helix motif with a polyglycine
hinge region. The uvrA1 or uvrA2 mutant, constructed by gene replacement, was more sensitive to DNA-damaging agents methylmethane sulfonate (MMS), mitomycin
C (MMC), or ultraviolet (UV) than the wild type. The uvrA1 mutant was four orders of magnitude more sensitive to UV irradiation and two orders of magnitude more sensitive to MMS than
the uvrA2 mutant. The uvrA1uvrA2 double mutant was one order of magnitude more sensitive to MMS, MMC, or UV than the uvrA1 single mutant. These results suggest that UvrA1 plays a more important role than UvrA2 in DNA repair in X. a. pv. citri. Both uvrA1 and uvrA2 genes were found to be constitutively expressed in the wild type and lexA1 or lexA2 mutant of X. a. pv. citri, and treatment of these cells with sublethal dose of MMC did not alter the expression of these two genes. Results
of electrophoresis mobility shift assays revealed that LexA1 or LexA2 does not bind to either the uvrA1 or the uvrA2 promoter. These results suggest that uvrA expression in X. a. pv. citri is not regulated by the SOS response system. 相似文献
15.
Kim YH Moody JD Freeman JP Brezna B Engesser KH Cerniglia CE 《Journal of industrial microbiology & biotechnology》2004,31(11):507-516
Polycyclic aromatic hydrocarbon (PAH) quinone reductase (PQR) and catechol-O-methyltransferase (COMT), from the PAH-degrading Mycobacterium vanbaalenii PYR-1, were demonstrated to be constitutive enzymes located in the soluble fraction of cell extracts. PQR activities for the reduction of 9,10-phenanthrenequinone and 4,5-pyrene- quinone were 1.40±0.13 and 0.12±0.01 mol min–1 mg-protein–1, respectively. The exogenous catechols alizarin, anthrarobin, 2,3-dihydroxynaphthalene and esculetin inhibited PQR activity. Anthrarobin (100 M) and esculetin (100 M) inhibited 4,5-pyrenequinone reduction by 64–92%. COMT was involved in the O-methylation of 1,2-dihydroxyphenanthrene to form 1-methoxy-2-hydroxyphenanthrene and 1,2-dimethoxyphenanthrene. Both pyrene and 1-hydroxypyrene were metabolized by M. vanbaalenii PYR-1 to form 1-methoxypyrene, 1-methoxy-2-hydroxypyrene, 1-hydroxy-2-methoxypyrene and 1,2-dimethoxypyrene. Among the catechols tested, anthrarobin showed the highest COMT activity (1.06±0.04 nmol/30 min–1 mg-protein–1). These results suggest that the PQR and COMT activities of M. vanbaalenii PYR-1 may play an important role in the detoxification of PAH catechols. 相似文献
16.
Summary. Optically pure (S)-3-p-hydroxyphenyllactic acid derivatives are important intermediates of peroxisome proliferator-activated receptor α/γ dual agonists
and heteropeptides. Many efforts have been made for synthesis of those intermediates, but there exist some flaws yet. We observed
that dielectric constants of organic solvents drastically affected diazotization of O-benzyl-L-tyrosine. Optically pure (S)-3-p-benzyloxyphenyllactic acid was obtained by simple recrystallization when DMF or DMSO of higher dielectric constant was used
as a co-solvent in diazotization of O-benzyl-L-tyrosine. It was easily turned into various optically pure (S)-3-p-hydroxyphenyllactic acid derivatives. 相似文献
17.
Mukherjee K Chava AK Mandal C Dey SN Kniep B Chandra S Mandal C 《Journal of cellular biochemistry》2008,105(3):724-734
We have previously demonstrated induction of O-acetylated sialoglycoproteins on lymphoblasts of childhood acute lymphoblastic leukaemia (ALL). These molecules promote survival of lymphoblasts by preventing apoptosis. Although O-acetylated sialoglycoproteins are over expressed, the status of O-acetylation of gangliosides and their role in lymphoblasts survival remains to be explored in ALL patients. Here, we have observed enhanced levels of 9-O-acetylated GD3 (9-O-AcGD3) in the lymphoblasts of patients and leukaemic cell line versus disialoganglioside GD3 in comparison to the normal cells. Localization of GD3 and 9-O-AcGD3 on mitochondria of patient's lymphoblasts has been demonstrated by immuno-electron microscopy. The exogenous administration of GD3-induced apoptosis in lymphoblasts as evident from the nuclear fragmentation and sub G0/G1 apoptotic peak. In contrast, 9-O-AcGD3 failed to induce such apoptosis. We further explored the mitochondria-dependent pathway triggered during GD3-induced apoptosis in lymphoblasts. GD3 caused a time-dependent depolarization of mitochondrial membrane potential, release of cytochrome c and 7.4- and 8-fold increased in caspase 9 and caspase 3 activity respectively. However, under identical conditions, an equimolar concentration of 9-O-AcGD3 failed to induce similar effects. Interestingly, 9-O-AcGD3 protected the lymphoblasts from GD3-induced apoptosis when administered in equimolar concentrations simultaneously. In situ de-O-acetylation of 9-O-AcGD3 with sodium salicylate restores the GD3-responsiveness to apoptotic signals. Although both GD3 and 9-O-acetyl GD3 localize to mitochondria, these two structurally related molecules may play different roles in ALL-disease biology. Taken together, our results suggest that O-acetylation of GD3, like that of O-acetylated sialoglycoproteins, might be a general strategy adopted by leukaemic blasts towards survival in ALL. 相似文献
18.
Toriba T Harada K Takamura A Nakamura H Ichikawa H Suzaki T Hirano HY 《Molecular genetics and genomics : MGG》2007,277(5):457-468
Members of the YABBY gene family have a general role that promotes abaxial cell fate in a model eudicot, Arabidopsis thaliana. To understand the function of YABBY genes in monocots, we have isolated all YABBY genes in Oryza sativa (rice), and revealed the spatial and temporal expression pattern of one of these genes, OsYABBY1. In rice, eight YABBY genes constitute a small gene family and are classified into four groups according to sequence similarity, exon-intron structure, and organ-specific expression patterns. OsYABBY1 shows unique spatial expression patterns that have not previously been reported for other YABBY genes, so far. OsYABBY1 is expressed in putative precursor cells of both the mestome sheath in the large vascular bundle and the abaxial sclerenchyma in the leaves. In the flower, OsYABBY1 is specifically expressed in the palea and lemma from their inception, and is confined to several cell layers of these organs in the later developmental stages. The OsYABBY1-expressing domains are closely associated with cells that subsequently differentiate into sclerenchymatous cells. These findings suggest that the function of OsYABBY1 is involved in regulating the differentiation of a few specific cell types and is unrelated to polar regulation of lateral organ development. 相似文献
19.