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21.
The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato 总被引:1,自引:0,他引:1
RAÚL HUERTAS LOURDES RUBIO OLIVIER CAGNAC MARÍA JESÚS GARCÍA‐SÁNCHEZ JUAN DE DIOS ALCHÉ KEES VENEMA JOSÉ ANTONIO FERNÁNDEZ MARÍA PILAR RODRÍGUEZ‐ROSALES 《Plant, cell & environment》2013,36(12):2135-2149
The endosomal LeNHX2 ion transporter exchanges H+ with K+ and, to lesser extent, Na+. Here, we investigated the response to NaCl supply and K+ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K+ the opposite was found. Analysis of mineral composition showed a higher K+ content in roots, shoots and xylem sap of transgenic plants and no differences in Na+ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na+/H+ and, above all, K+/H+ transport activity in root intracellular membrane vesicles. Under K+ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K+ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K+ depletion rates and half cytosolic K+ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K+ and lower cytosolic K+ activity than untransformed plants. These results indicate the fundamental role of K+ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress. 相似文献
22.
Rebecca A. Faulkner Andrew D. Nguyen Youngah Jo Russell A. DeBose-Boyd 《Journal of lipid research》2013,54(4):1011-1022
In mammalian cells, levels of the integral membrane proteins 3-hydroxy-3-methylglutaryl-CoA reductase and Insig-1 are controlled by lipid-regulated endoplasmic reticulum-associated degradation (ERAD). The ERAD of reductase slows a rate-limiting step in cholesterol synthesis and results from sterol-induced binding of its membrane domain to Insig-1 and the highly related Insig-2 protein. Insig binding bridges reductase to ubiquitin ligases that facilitate its ubiquitination, thereby marking the protein for cytosolic dislocation and proteasomal degradation. In contrast to reductase, Insig-1 is subjected to ERAD in lipid-deprived cells. Sterols block this ERAD by inhibiting Insig-1 ubiquitination, whereas unsaturated fatty acids block the reaction by preventing the protein''s cytosolic dislocation. In previous studies, we found that the membrane domain of mammalian reductase was subjected to ERAD in Drosophila S2 cells. This ERAD was appropriately accelerated by sterols and required the action of Insigs, which bridged reductase to a Drosophila ubiquitin ligase. We now report reconstitution of mammalian Insig-1 ERAD in S2 cells. The ERAD of Insig-1 in S2 cells mimics the reaction that occurs in mammalian cells with regard to its inhibition by either sterols or unsaturated fatty acids. Genetic and pharmacologic manipulations coupled with subcellular fractionation indicate that Insig-1 and reductase are degraded through distinct mechanisms that are mediated by different ubiquitin ligase complexes. Together, these results establish Drosophila S2 cells as a model system to elucidate mechanisms through which lipid constituents of cell membranes (i.e., sterols and fatty acids) modulate the ERAD of Insig-1 and reductase. 相似文献
23.
Wenxiu Ye Mohammad Anowar Hossain Shintaro Munemasa Yoshimasa Nakamura Izumi C. Mori Yoshiyuki Murata 《Journal of plant physiology》2013
We recently demonstrated that endogenous abscisic acid (ABA) is involved in methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we investigated whether endogenous ABA is involved in MeJA-induced reactive oxygen species (ROS) and nitric oxide (NO) production and cytosolic alkalization in guard cells using an ABA-deficient Arabidopsis mutant, aba2-2, and an inhibitor of ABA biosynthesis, fluridon (FLU). The aba2-2 mutation impaired MeJA-induced ROS and NO production. FLU inhibited MeJA-induced ROS production in wild-type guard cells. Pretreatment with 0.1 μM ABA, which does not induce stomatal closure in the wild type, complemented the insensitivity to MeJA of the aba2-2 mutant. However, MeJA induced cytosolic alkalization in both wild-type and aba2-2 guard cells. These results suggest that endogenous ABA is involved in MeJA-induced ROS and NO production but not in MeJA-induced cytosolic alkalization in Arabidopsis guard cells. 相似文献
24.
Kazuyuki Maekawa Yasutaka Miyoshi Kenshiro Tsuru 《Bioscience, biotechnology, and biochemistry》2013,77(10):1951-1956
Dextran was subjected to oxidative scission by periodate, followed by ring closure with nitromethane to form nitrodextran. The nitro group attached to the ring was reduced by LiAlH4 to yield amino-polysaccharide of which the molecular weight was about 10,000. It became clear that nitrodextran consisted of 3-deoxy-3-nitro-mannopyranoside, -glucopyranoside, -galactopyranoside and -talopyranoside and their molar ratio was 6: 5: 1: 2 as determined by column Chromatographic separation and gas Chromatographic analysis of the methanolyzate of nitro-dextran. 相似文献
25.
Wensu Yuan Carlos F. Ibez Zhi Lin 《Biological reviews of the Cambridge Philosophical Society》2019,94(4):1282-1293
The death domain (DD) is a globular protein motif with a signature feature of an all‐helical Greek‐key motif. It is a primary mediator of a variety of biological activities, including apoptosis, cell survival and cytoskeletal changes, which are related to many neurodegenerative diseases, neurotrauma, and cancers. DDs exist in a wide range of signalling proteins including p75 neurotrophin receptor (p75NTR), a member of the tumour necrosis factor receptor superfamily. The specific signalling mediated by p75NTR in a given cell depends on the type of ligand engaging the extracellular domain and the recruitment of cytosolic interactors to the intracellular domain, especially the DD, of the receptor. In solution, the p75NTR‐DDs mainly form a symmetric non‐covalent homodimer. In response to extracellular signals, conformational changes in the p75NTR extracellular domain (ECD) propagate to the p75NTR‐DD through the disulfide‐bonded transmembrane domain (TMD) and destabilize the p75NTR‐DD homodimer, leading to protomer separation and exposure of binding sites on the DD surface. In this review, we focus on recent advances in the study of the structural mechanism of p75NTR‐DD signalling through recruitment of diverse intracellular interactors for the regulation and control of diverse functional outputs. 相似文献
26.
We observed a spot on two-dimensional (2-D) gel in the epileptic mutant strain El mice with a similar molecular weight but with a different isoelectric point of approximately 0.2, compared with its mother strain ddY mice. The collected protein from the El mice was identified as cytosolic NADP+-dependent isocitrate dehydrogenase by internal amino acid sequencing. The enzyme is known to be maximally active during the development of the brain and to play an important role in NADPH production for fatty acids and cholesterol synthesis. In addition, alterations in cholesterol synthesis early in the development of the mammalian brain have been reported to lead to chronic epilepsy. The results in the present study therefore suggest that cytosolic NADP+-dependent isocitrate dehydrogenase might be involved in the epileptogenesis of the El mouse. 相似文献
27.
The symbiotic hydrothermal vent tubeworm Riftia pachyptila needs to supply its internal bacterial symbionts with carbon dioxide, their inorganic carbon source. Our aim in this study was to characterize the carbonic anhydrase (CA) involved in CO(2) transport and conversion at various steps in the plume and the symbiotic tissue, the trophosome. A complete 1209 kb cDNA has been sequenced from the trophosome and identified as a putative alpha-CA based on BLAST analysis and the similarities of total deduced amino-acid sequence with those from the GenBank database. In the plume, the putative CA sequence obtained from cDNA library screening was 90% identical to the trophosome CA, except in the first 77 nucleotides downstream from the initiation site identified on trophosome CA. A phylogenetic analysis showed that the annelidan Riftia CA (CARp) emerges clustered with invertebrate CAs, the arthropodan Drosophila CA and the cnidarian Anthopleura CA. This invertebrate cluster appeared as a sister group of the cluster comprising mitochondrial and cytosolic isoforms in vertebrates: CAV, CAI II and III, and CAVII. However, amino acid sequence alignment showed that Riftia CA was closer to cytosolic CA than to mitochondrial CA. Combined biochemical approaches revealed two cytosolic CAs with different molecular weights and pI's in the plume and the trophosome, and the occurrence of a membrane-bound CA isoform in addition to the cytosolic one in the trophosome. The physiologic roles of cytosolic CA in both tissues and supplementary membrane-bound CA isoform in the trophosome in the optimization of CO(2) transport and conversion are discussed. 相似文献
28.
Brown EM 《Cell biochemistry and biophysics》2000,33(1):63-95
The cloning of a G protein-coupled, extracellular Ca2+ (Ca
o
2+
)-sensing receptor (CaR) has afforded a molecular basis for a number of the known effects of Ca
o
2+
on tissues involved in maintaining systemic calcium homeostasis, especially parathyroid gland and kidney. In addition to
providing molecular tools for showing that CaR messenger RNA and protein are present within these tissues, the cloned CaR
has permitted documentation that several human diseases are the result of inactivating or activating mutations of this receptor
as well as generation of mice that have targeted disruption of the CaR gene. Characteristic changes in the functions of parathyroid
and kidney in these patients as well as in the CaR “knockout” mice have elucidated considerably the CaR’s physiological roles
in mineral ion homeostasis. Nevertheless, a great deal remains to be learned about how this receptor regulates the functioning
of other tissues involved in Ca
o
2+
metabolism, such as bone and intestine. Further study of these human diseases and of the mouse models will doubtless be useful
in gaining additional understanding of the CaR’s roles in these latter tissues. Furthermore, we understand little of the CaR’s
functions in tissues that are not directly involved in systemic mineral ion metabolism, where the receptor probably serves
diverse other roles. Some of these functions may be related to the control of intra- and local extracellular concentrations
of Ca2+, while others may be unrelated to either systemic or local ionic homeostasis. In any case, the CaR and conceivably additional
receptors/sensors for Ca2+ or other extracellular ions represent versatile regulators of a wide variety of cellular functions and represent important
targets for novel classes of therapeutics. 相似文献
29.
A single degenerate glutamine synthetase (GS)-specific primer was used to amplify the 3′ end of cDNAs derived from different
GS genes that are expressed in leaves and roots of sunflower (Helianthus annuus L. cv. Peredovic). Four types of GS cDNA (I,
II, III and IV) were simultaneously amplified from leaves and five types (I, II, V, VI, VII) from roots with a minimum investment
of time and experimental work. cDNAs II, III and IV encode chloroplastic isoforms as deduced by the presence of chloroplastic
GS-specific features in their sequences. The rest of cDNAs codifies cytosolic isoforms. Using cDNA-specific probes and primers,
homologous sequences to all GS cDNAs amplified from cv. Peredovic, except to cDNAs III and IV, were detected in the inbred
line R41. This result strongly suggests that the three cDNAs for chloroplastic isoform are allelic sequences from the same
locus, and since cDNA type IV contains sequences derived from cDNAs II and III, it indicates a recombinational origin. The
results presented are consistent with the existence of a GS gene family in sunflower with at least five members. Four of them,
named ggs1.1 to ggs1.4, codify for the cytosolic isoforms (cDNAs I, V, VI and VII). A fifth member, named ggs2, from which
three allelic sequences (cDNAs II, III and IV) have been cloned, encodes the chloroplastic isoform.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
30.
A cDNA clone for the cytosolic Cu/Zn superoxide dismutase (Cu/Zn SOD) from Chinese cabbage (Brassica campestris ssp.pekinensis) was isolated and its DNA sequence was determined. The cDNA clone contains a complete coding sequence which encodes a protein
of 152 amino acids and a 3-untranslated region including a poly A signal. The deduced amino acid sequence shows that it is
highly homologous to the Cu/Zn SODs from other plants (60–90%). The lack of a putative chloroplast targeting transit peptide
indicates that the clone represents a cytosolic form of Cu/Zn SOD. Genomic Southern hybridization suggests that cytosolic
Cu/Zn SOD genes are present in 1 or 2 copies per genome. 相似文献