Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.55 (PTR)
 433 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plants need to acquire nitrogen (N) efficiently from the soil for growth. Nitrate is one of the major N sources for higher plants. Therefore, nitrate uptake and allocation are key factors in efficient N utilization. Membrane-bound transporters are required for nitrate uptake from the soil and for the inter- and intracellular movement of nitrate inside the plants. Four gene families, nitrate transporter 1/peptide transporter (NRT1/PTR), NRT2, chloride channel (CLC), and slow anion channel-associated 1 homolog 3 (SLAC1/SLAH), are involved in nitrate uptake, allocation, and storage in higher plants. Recent studies of these transporters or channels have provided new insights into the molecular mechanisms of nitrate uptake and allocation. Interestingly, several of these transporters also play versatile roles in nitrate sensing, plant development, pathogen defense, and/or stress response.
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PMID:Uptake, allocation and signaling of nitrate. 2265 80

Nitrate is an important nutrient required for plant growth. It also acts as a signal regulating plant development. Nitrate is actively taken up and transported by nitrate transporters (NRT), which form a large family with many members and distinct functions. In contrast to Arabidopsis and rice there is little information about the NRT family in woody plants such as Populus. In this study, a comprehensive analysis of the Populus NRT family was performed. Sixty-eight PtNRT1/PTR, 6 PtNRT2, and 5 PtNRT3 genes were identified in the P. trichocarpa genome. Phylogenetic analysis confirmed that the genes of the NRT family are divided into three clades: NRT1/PTR with four subclades, NRT2, and NRT3. Topological analysis indicated that all members of PtNRT1/PTR and PtNRT2 have 8 to 12 trans-membrane domains, whereas the PtNRT3 proteins have no or up to two trans-membrane domains. Four PtNRT3 members were predicted as secreted proteins. Microarray analyses revealed tissue-specific expression patterns of PtNRT genes with distinct clusters of NRTs for roots, for the elongation zone of the apical stem segment and the developing xylem and a further cluster for leaves, bark and wood. A comparison of different poplar species (P. trichocarpa, P. tremula, P. euphratica, P. fremontii x P. angustifolia, and P. x canescens) showed that the tissue-specific patterns of the NRT genes varied to some extent with species. Bioinformatic analysis of putative cis-regulatory elements in the promoter regions of PtNRT family retrieved motifs suggesting the regulation of the NRT genes by N metabolism, by energy and carbon metabolism, and by phytohormones and stress. Multivariate analysis suggested that the combination and abundance of motifs in distinct promoters may lead to tissue-specificity. Our genome wide analysis of the PtNRT genes provides a valuable basis for functional analysis towards understanding the role of nitrate transporters for tree growth.
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PMID:The nitrate transporter (NRT) gene family in poplar. 2397 27

Nitrogen (N) is quantitatively the main nutrient required by coffee plants, with acquisition mainly by the roots and mostly exported to coffee beans. Nitrate (NO3-) and ammonium (NH4+) are the most important inorganic sources for N uptake. Several N transporters encoded by different gene families mediate the uptake of these compounds. They have an important role in source preference for N uptake in the root system. In this study, we performed a genome-wide analysis, including in silico expression and phylogenetic analyses of AMT1, AMT2, NRT1/PTR, and NRT2 transporters in the recently sequenced Coffea canephora genome. We analyzed the expression of six selected transporters in Coffea arabica roots submitted to N deficiency. N source preference was also analyzed in C. arabica using isotopes. C. canephora N transporters follow the patterns observed for most eudicots, where each member of the AMT and NRT families has a particular role in N mobilization, and where some of these are modulated by N deficiency. Despite the prevalence of putative nitrate transporters in the Coffea genome, ammonium was the preferential inorganic N source for N-starved C. arabica roots. This data provides an important basis for fundamental and applied studies to depict molecular mechanisms involved in N uptake in coffee trees.
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PMID:Genome-wide identification, classification and transcriptional analysis of nitrate and ammonium transporters in Coffea. 2839 92

Potassium and nitrogen are essential macronutrients for plant growth and have a positive impact on crop yield. Previous studies have indicated that the absorption and translocation of K+ and NO3- are correlated with each other in plants; however, the molecular mechanism that coordinates K+ and NO3- transport remains unknown. In this study, using a forward genetic approach, we isolated a low-K+-sensitive Arabidopsis thaliana mutant, lks2, that showed a leaf chlorosis phenotype under low-K+ conditions. LKS2 encodes the transporter NRT1.5/NPF7.3, a member of the NRT1/PTR (Nitrate Transporter 1/Peptide Transporter) family. The lks2/nrt1.5 mutants exhibit a remarkable defect in both K+ and NO3- translocation from root to shoot, especially under low-K+ conditions. This study demonstrates that LKS2 (NRT1.5) functions as a proton-coupled H+/K+ antiporter. Proton gradient can promote NRT1.5-mediated K+ release out of root parenchyma cells and facilitate K+ loading into the xylem. This study reveals that NRT1.5 plays a crucial role in K+ translocation from root to shoot and is also involved in the coordination of K+/NO3- distribution in plants.
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PMID:NRT1.5/NPF7.3 Functions as a Proton-Coupled H+/K+ Antiporter for K+ Loading into the Xylem in Arabidopsis. 2873 44

Nitrate is not only an important nutrient but also a signaling molecule for plants. A few of key molecular components involved in primary nitrate responses have been identified mainly by forward and reverse genetics as well as systems biology, however, many underlining mechanisms of nitrate regulation remain unclear. In this study, we show that the expression of NRT1.1, which encodes a nitrate sensor and transporter (also known as CHL1 and NPF6.3), is modulated by NIN-like protein 7 (NLP7). Genetic and molecular analyses indicate that NLP7 works upstream of NRT1.1 in nitrate regulation when NH4+ is present, while in absence of NH4+, it functions in nitrate signaling independently of NRT1.1. Ectopic expression of NRT1.1 in nlp7 resulted in partial or complete restoration of nitrate signaling (expression from nitrate-regulated promoter NRP), nitrate content and nitrate reductase activity in the transgenic lines. Transcriptome analysis revealed that four nitrogen-related clusters including amino acid synthesis-related genes and members of NRT1/PTR family were modulated by both NLP7 and NRT1.1. In addition, ChIP and EMSA assays results indicated that NLP7 may bind to specific regions of the NRT1.1 promoter. Thus, NLP7 acts as an important factor in nitrate signaling via regulating NRT1.1 under NH4+ conditions.
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PMID:The Arabidopsis NLP7 gene regulates nitrate signaling via NRT1.1-dependent pathway in the presence of ammonium. 2936 94

Nitrate transporter 2.5 (NRT2.5) was originally characterized as the transporter for nitrogen (N) limitation. In Arabidopsis, NRT2.5 is expressed mainly under extremely low NO3 - and N starvation conditions, and this must work in conjunction with NAR2.1. NRT2.5 is expressed both in the roots and leaves in Arabidopsis, poplars, tea trees and cassava. This is also expressed in the seeds of Arabidopsis and wheat. In wheat, NRT2.5 is expressed in the embryo and shell and plays a role in the accumulation of NO3 - in the seeds. In maize, this is also expressed in silk, cobs and tassel husk leaves. In rice, OsNRT2.5 (also known as OsNRT2.3a) may help the species to remove NO3 - from the roots to shoots. In addition, NRT2.5 may interact with TGA3, MYC1, LBD37, LBD38, TaNAC2 and other transcription factors and participate in the transmission of NO3 - signals. The present review summarizes the functions of NRT2.5 in different plant species, which may help plant breeders and molecular biologists to improve crop yield. Abbreviations: NRT, Nitrate transporter; NUE, nitrogen use efficiency; PTR, peptide transporter; NPF, nitrate peptide transporter family; CLC, chloride channel; LAC1/SLAH, slow anion channel-associated 1 homolog 3; LATS, low-affinity transporter systems; HATS, high-affinity transport systems; NNP, nitrate-nitrite-porter; MFS, major facilitator superfamily.
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PMID:The expression patterns and putative function of nitrate transporter 2.5 in plants. 3286 94