排序方式: 共有77条查询结果,搜索用时 31 毫秒
1.
John S Schutzbach 《Glycoconjugate journal》1997,14(2):175-182
The enzymes in the dolichol pathway are membrane-proteins that utilize a combination of hydrophilic and extremely hydrophobic
substrates. The enzymes in this pathway that have been purified and characterized to any extent have either been shown to
be stabilized by mixed phospholipid/detergent micelles, or else require a lipid matrix for catalytic activity. Further understanding
of the mechanisms of these essential enzymes may require developing methods for the reconstitution of the glycosyltransferases
and their hydrophobic substrates in appropriate lipid matrices. Abbreviations: CHO, Chinese hamster ovary; Dol, dolichol;
DAG, diacylglycerol; DOPC, dioleolylphosphatidylcholine; DOPE, dioleolyphosphatidylethanolamine; ER, endoplasmic reticulum;
PC, phosphatidylcholine; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PI, phosphatidylinositol
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
2.
3.
Vibha Pandey Yogeshwar Vikram Dhar Parul Gupta Sumit K Bag Neelam Atri Mehar Hasan Asif Prabodh Kumar Trivedi Pratibha Misra 《BMC bioinformatics》2015,16(1)
Background
Sterol glycosyltransferases (SGTs) are ubiquitous but one of the most diverse group of enzymes of glycosyltransferases family. Members of this family modulate physical and chemical properties of secondary plant products important for various physiological processes. The role of SGTs has been demonstrated in the biosynthesis of pharmaceutically important molecules of medicinal plants like Withania somnifera.Results
Analysis suggested conserved behaviour and high similarity in active sites of WsSGTs with other plant GTs. Substrate specificity of WsSGTs were analysed through docking performance of WsSGTs with different substrates (sterols and withanolides). Best docking results of WsSGTL1 in the form of stable enzyme-substrate complex having lowest binding energies were obtained with brassicasterol, transandrosteron and WsSGTL4 with solasodine, stigmasterol and 24-methylene cholesterol.Conclusion
This study reveals topological characters and conserved nature of two SGTs from W. somnifera (WsSGTs) i.e. WsSGTL1 and WsSGTL4. However, besides being ubiquitous in nature and with broad substrate specificity, difference between WsSGTL1 and WsSGTL4 is briefly described by difference in stability (binding energy) of enzyme-substrate complexes through comparative docking.Electronic supplementary material
The online version of this article (doi:10.1186/s12859-015-0563-7) contains supplementary material, which is available to authorized users. 相似文献4.
Arabinogalactan proteins are abundant cell surface proteoglycans in plants and are implicated to act as developmental markers during plant growth. We previously reported that AtGALT31A, AtGALT29A, and AtGLCAT14A-C, which are involved in the biosynthesis of arabinogalactan proteins, localize not only to the Golgi cisternae but also to smaller compartments, which may be a part of the unconventional protein secretory pathway in plants. In Poulsen et al.,1 we have demonstrated increased targeting of AtGALT29A to small compartments when Y144 is substituted with another amino acid, and we implicated a role for Y144 in the subcellular targeting of AtGALT29A. In this paper, we are presenting another aspect of Y144 substitution in AtGALT29A; namely, Y144A construct demonstrated a 2.5-fold increase while Y144E construct demonstrated a 2-fold decrease in the galactosyltransferase activity of AtGALT29A. Therefore, the electrostatic status of Y144, which is regulated by an unknown kinase/phosphatase system, may regulate AtGALT29A enzyme activity. Moreover, we have identified additional proteins, apyrase 3 (APY3; At1g14240) and UDP-glucuronate epimerases 1 and 6 (GAE1, At4g30440; GAE6, At3g23820), from Arabidopsis thaliana that co-localize with AtGALT31A in the small compartments when expressed transiently in Nicotiana benthamiana. These proteins may play roles in nucleotide sugar metabolism in the small compartments together with arabinogalactan glycosyltransferases. 相似文献
5.
The dystrophin glycoprotein complex (DGC) is an assembly of proteins spanning the sarcolemma of skeletal muscle cells. Defects
in the DGC appear to play critical roles in several muscular dystrophies due to disruption of basement membrane organization.
O-mannosyl oligosaccharides on α-dystroglycan, a major extracellular component of the DGC, are essential for normal binding
of α-dystroglycan to ligands (such as laminin) in the extracellular matrix and subsequent signal transmission to actin in
the cytoskeleton of the muscle cell. Muscle-Eye-Brain disease (MEB) and Walker-Warburg Syndrome (WWS) have mutations in genes
encoding glycosyltransferases needed for O-mannosyl oligosaccharide synthesis. Myodystrophic myd mice and humans with Fukuyama Congenital Muscular Dystrophy (FCMD), congenital muscular dystrophy due to defective fukutin-related
protein (FKRP) and MDC1D have mutations in putative glycosyltransferases. These human congenital muscular dystrophies and
the myd mouse are associated with defective glycosylation of α-dystroglycan. It is expected other congenital muscular dystrophies
will prove to have mutations in genes involved in glycosylation. Published in 2004.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Carsten P. Ade Felix Bemm James M.J. Dickson Christian Walter Philip J. Harris 《The Plant journal : for cell and molecular biology》2014,78(2):305-318
Using a functional genomics approach, four candidate genes (PtGT34A, PtGT34B, PtGT34C and PtGT34D) were identified in Pinus taeda. These genes encode CAZy family GT34 glycosyltransferases that are involved in the synthesis of cell‐wall xyloglucans and heteromannans. The full‐length coding sequences of three orthologs (PrGT34A, B and C) were isolated from a xylem‐specific cDNA library from the closely related Pinus radiata. PrGT34B is the ortholog of XXT1 and XXT2, the two main xyloglucan (1→6)‐α‐xylosyltransferases in Arabidopsis thaliana. PrGT34C is the ortholog of XXT5 in A. thaliana, which is also involved in the xylosylation of xyloglucans. PrGT34A is an ortholog of a galactosyltransferase from fenugreek (Trigonella foenum‐graecum) that is involved in galactomannan synthesis. Truncated coding sequences of the genes were cloned into plasmid vectors and expressed in a Sf9 insect cell‐culture system. The heterologous proteins were purified, and in vitro assays showed that, when incubated with UDP‐xylose and cellotetraose, cellopentaose or cellohexaose, PrGT34B showed xylosyltransferase activity, and, when incubated with UDP‐galactose and the same cello‐oligosaccharides, PrGT34B showed some galactosyltransferase activity. The ratio of xylosyltransferase to galactosyltransferase activity was 434:1. Hydrolysis of the galactosyltransferase reaction products using galactosidases showed the linkages formed were α‐linkages. Analysis of the products of PrGT34B by MALDI‐TOF MS showed that up to three xylosyl residues were transferred from UDP‐xylose to cellohexaose. The heterologous proteins PrGT34A and PrGT34C showed no detectable enzymatic activity. 相似文献
7.
Based on the analysis of amino acid sequence and simulated structure, saturation mutagenesis was performed to explore the role of the site p176 of cyclodextrin glucosytransferase (CGTase) from Bacillus sp. Y112. Compared to the wild-type, mutant P176G showed 10.4 % improvement in conversion from starch to cyclodextrins (CDs), whose β-CD yield increased by 6% and α-CD yield decreased by 8%. Mutants P176L and P176I were increased by 7.9 % and 9.4 % on CDs production, indicating replacement of hydrophobic amino acids significantly improved in cyclization activity. Kinetics studies indicated the substrate affinity of P176G and P176K were increase by 13 % and 14 %, and the catalytic efficiency of P176K was increase by 14 %. In addition, the optimal temperature of mutants transformed from 50℃ to 40℃ and the optimal pH shifted from 10.0 to 8.0. These results indicate that the site P176 plays a critical role in catalytic activity, product specificity and enzymatic properties of CGTase. 相似文献
8.
Glycosyltransferases (GTs) are diverse enzymes organized into 65 families. X-ray crystallography and in silico studies have shown many of these to belong to two structural superfamilies: GT-A and GT-B. Through application of fold recognition and iterated sequence searches, we demonstrate that families 60, 62, and 64 may also be grouped into the GT-A fold superfamily. Analysis of conserved acidic residues suggests that catalytic sites are better conserved in superfamily GT-B than in GT-A. Although 26% and 29% of GT families may now be confidently placed in superfamilies GT-A and GT-B, respectively, the remaining 45% of families bear no discernible resemblance to either superfamily, which, given the sensitivity of modern fold recognition methods, suggests the existence of novel structural scaffolds associated with GT activity. Furthermore, bioinformatics studies indicate the apparent ease with which mechanism-inverting or retaining-may change during evolution. 相似文献
9.
Sulfoglucuronyl carbohydrate (SGC), reactive with antibody against human natural killer cell antigen, is expressed in several glycolipids, glycoproteins and proteoglycans of the nervous system and has been implicated in cell-cell recognition, neurite outgrowth and neuronal migration during development, through its interaction with SGC-binding protein (SBP) 1. However, sulfotransferase (ST) null mutant mice, which lack SGC, were shown to have normal development with usual gross anatomy of the nervous system and other organs. Failure to observe a severe phenotype in the ST null mice prompted us to determine the compensatory molecular replacement of SGC by analyzing the carbohydrate of glycolipids and glycoproteins of the ST mutant nervous system. In the ST null mice, SGC-containing molecules were absent; instead the precursor glucuronyl carbohydrate (GC)-containing molecules accumulated. Other relevant glycolipids and proteins were not affected. The GC molecules in the mutant were localized at the same anatomical sites in the nervous system as the SGC molecules in the wild type. In vitro binding studies showed that, similar to sulfoglucuronyl glycolipids, glucuronyl glycolipids interacted with SBP-1, but with a lower binding capacity. In vitro studies with explant cultures of cerebellum indicated that neurite outgrowth and cell migration were not significantly affected in the mutant, possibly owing to interaction of SBP-1 with GC molecules. The results suggested that in vivo SBP-1-GC interaction was sufficient to allow normal neurite outgrowth and cell migration in the mutant, giving rise to a wild-type phenotype. However, the role of other compensatory molecules involved in these processes cannot be completely ruled out. 相似文献
10.