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11.
Pandey GK Pandey A Reddy VS Deswal R Bhattacharya A Upadhyaya KC Sopory SK 《Journal of biosciences》2007,32(2):251-260
Entamoeba histolytica contains a novel calcium-binding protein like calmodulin, which was discovered earlier, and we have reported the presence
of its homologue(s) and a dependent protein kinase in plants. To understand the functions of these in plants, a cDNA encoding
a calcium-binding protein isolated from Entamoeba histolytica (EhCaBP) was cloned into vector pBI121 in antisense orientation and transgenic tobacco plants were raised. These plants showed
variation in several phenotypic characters, of which two distinct features, more greenness and leaf thickness, were inherited
in subsequent generations. The increase in the level of total chlorophyll in different plants ranged from 60% to 70%. There
was no major change in chloroplast structure and in the protein level of D1, D2, LHCP and RuBP carboxylase. These morphological
changes were not seen in antisense calmodulin transgenic tobacco plants, nor was the calmodulin level altered in EhCaBP antisense
plants.
The results of this paper have been granted US Patent No. 6,791,009. 相似文献
12.
We describe here a novel sensor for cGMP based on the GAF domain of the cGMP-binding, cGMP-specific phosphodiesterase 5 (PDE5) using bioluminescence resonance energy transfer (BRET). The wild type GAFa domain, capable of binding cGMP with high affinity, and a mutant (GAFa F163A) unable to bind cGMP were cloned as fusions between GFP and Rluc for BRET (2) assays. BRET (2) ratios of the wild type GAFa fusion protein, but not GAFa F163A, increased in the presence of cGMP but not cAMP. Higher basal BRET (2) ratios were observed in cells expressing the wild type GAFa domain than in cells expressing GAFa F163A. This was correlated with elevated basal intracellular levels of cGMP, indicating that the GAF domain could act as a sink for cGMP. The tandem GAF domains in full length PDE5 could also sequester cGMP when the catalytic activity of PDE5 was inhibited. Therefore, these results describe a cGMP sensor utilizing BRET (2) technology and experimentally demonstrate the reservoir of cGMP that can be present in cells that express cGMP-binding GAF domain-containing proteins. PDE5 is the target for the anti-impotence drug sildenafil citrate; therefore, this GAF-BRET (2) sensor could be used for the identification of novel compounds that inhibit cGMP binding to the GAF domain, thereby regulating PDE5 catalytic activity. 相似文献
13.
Earlier we have shown the role of glyoxalase overexpression in conferring salinity tolerance in transgenic tobacco. We now
demonstrate the feasibility of same in a crop like rice through overproduction of glyoxalase II. The rice glyoxalase II was
cloned in pCAMBIA1304 and transformed into rice (Oryza sativa cv PB1) via Agrobacterium. The transgenic plants showed higher constitutive activity of glyoxalase II that increased further
upon salt stress, reflecting the upregulation of endogenous glyoxalase II. The transgenic rice showed higher tolerance to
toxic concentrations of methylglyoxal (MG) and NaCl. Compared with non-transgenics, transgenic plants at the T1 generation
exhibited sustained growth and more favorable ion balance under salt stress conditions.
Sneh L. Singla-Pareek and Sudesh Kumar Yadav have contributed equally to this work. 相似文献
14.
BMP4 is synthesized as an inactive precursor that is cleaved at two sites during maturation: initially at a site (S1) adjacent to the ligand domain, and then at an upstream site (S2) within the prodomain. Cleavage at the second site regulates the stability of mature BMP4 and this in turn influences its signaling intensity and range of action. The Drosophila ortholog of BMP4, Dpp, functions as a long- or short-range signaling molecule in the wing disc or embryonic midgut, respectively but mechanisms that differentially regulate its bioactivity in these tissues have not been explored. In the current studies we demonstrate, by dpp mutant rescue, that cleavage at the S2 site of proDpp is required for development of the wing and leg imaginal discs, whereas cleavage at the S1 site is sufficient to rescue Dpp function in the midgut. Both the S1 and S2 sites of proDpp are cleaved in the wing disc, and S2-cleavage is essential to generate sufficient ligand to exceed the threshold for pMAD activation at both short- and long-range in most cells. By contrast, proDpp is cleaved at the S1 site alone in the embryonic mesoderm and this generates sufficient ligand to activate physiological target genes in neighboring cells. These studies provide the first biochemical and genetic evidence that selective cleavage of the S2 site of proDPP provides a tissue-specific mechanism for regulating Dpp activity, and that differential cleavage can contribute to, but is not an absolute determinant of signaling range. 相似文献
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We have successfully expressed enzymatically active plant topoisomerase II in Escherichia coli for the first time, which has enabled its biochemical characterization. Using a PCR-based strategy, we obtained a full-length cDNA and the corresponding genomic clone of tobacco topoisomerase II. The genomic clone has 18 exons interrupted by 17 introns. Most of the 5 and 3 splice junctions follow the typical canonical consensus dinucleotide sequence GU-AG present in other plant introns. The position of introns and phasing with respect to primary amino acid sequence in tobacco TopII and Arabidopsis TopII are highly conserved, suggesting that the two genes are evolved from the common ancestral type II topoisomerase gene. The cDNA encodes a polypeptide of 1482 amino acids. The primary amino acid sequence shows a striking sequence similarity, preserving all the structural domains that are conserved among eukaryotic type II topoisomerases in an identical spatial order. We have expressed the full-length polypeptide in E. coli and purified the recombinant protein to homogeneity. The full-length polypeptide relaxed supercoiled DNA and decatenated the catenated DNA in a Mg2+- and ATP-dependent manner, and this activity was inhibited by 4-(9-acridinylamino)-3-methoxymethanesulfonanilide (m-AMSA). The immunofluorescence and confocal microscopic studies, with antibodies developed against the N-terminal region of tobacco recombinant topoisomerase II, established the nuclear localization of topoisomerase II in tobacco BY2 cells. The regulated expression of tobacco topoisomerase II gene under the GAL1 promoter functionally complemented a temperature-sensitive TopII
ts yeast mutant. 相似文献
18.
Saxena M Bisht R Roy SD Sopory SK Bhalla-Sarin N 《Biochemical and biophysical research communications》2005,336(3):813-819
A cDNA (1061 bp) Bj glyII was cloned from a mannitol induced library of Brassica juncea. It encoded a protein of 335 amino acids with a molecular weight of 36.52 kDa. The deduced amino acid sequence of the clone showed 92% and 56% identity with Pennisetum and rice glyoxalase II, respectively, and 30% identity was observed with the human glyoxalase II. Search for the identical residues revealed the presence of highly conserved THHHXDH domain which is involved in zinc binding. p-NN and pSORT analysis of this sequence revealed a N-terminal mitochondrial target peptide. The cDNA was cloned in pMAL and a fusion protein with MBP (78 kDa) was expressed in Escherichia coli. The recombinant protein was purified approximately sixfold by affinity purification on amylose column and showed its pH optima at 7.0. The K(m) was determined to be 120 microM using S-d-lactoylglutathione as substrate. The expression of Bj glyII under various abiotic stress conditions showed that it is upregulated by salinity, heavy metal stress, and ABA. 相似文献
19.
Goldman DC Hackenmiller R Nakayama T Sopory S Wong C Kulessa H Christian JL 《Development (Cambridge, England)》2006,133(10):1933-1942
ProBMP4 is initially cleaved at a site adjacent to the mature ligand (the S1 site) allowing for subsequent cleavage at an upstream (S2) site. Mature BMP4 synthesized from a precursor in which the S2 site cannot be cleaved remains in a complex with the prodomain that is targeted for lysosomal degradation, and is thus less active when overexpressed in Xenopus. Here we report that mice carrying a point mutation that prevents S2 processing show severe loss of BMP4 activity in some tissues, such as testes and germ cells, whereas other tissues that are sensitive to Bmp4 dosage, such as the limb, dorsal vertebrae and kidney, develop normally. In a haploinsufficient background, inability to cleave the S2 site leads to embryonic and postnatal lethality due to defects in multiple organ systems including the allantois, placental vasculature, ventral body wall, eye and heart. These data demonstrate that cleavage of the S2 site is essential for normal development and, more importantly, suggest that this site might be selectively cleaved in a tissue-specific fashion. In addition, these studies provide the first genetic evidence that BMP4 is required for dorsal vertebral fusion and closure of the ventral body wall. 相似文献
20.