Molecular Analysis of the Prostacyclin Receptor’s Interaction with the PDZ1 Domain of Its Adaptor Protein PDZK1

The prostanoid prostacyclin, or prostaglandin I2, plays an essential role in many aspects of cardiovascular disease. The actions of prostacyclin are mainly mediated through its activation of the prostacyclin receptor or, in short, the IP. In recent studies, the cytoplasmic carboxy-terminal domain of the IP was shown to bind several PDZ domains of the multi-PDZ adaptor PDZK1. The interaction between the two proteins was found to enhance cell surface expression of the IP and to be functionally important in promoting prostacyclin-induced endothelial cell migration and angiogenesis. To investigate the interaction of the IP with the first PDZ domain (PDZ1) of PDZK1, we generated a nine residue peptide (KK411IAACSLC417) containing the seven carboxy-terminal amino acids of the IP and measured its binding affinity to a recombinant protein corresponding to PDZ1 by isothermal titration calorimetry. We determined that the IP interacts with PDZ1 with a binding affinity of 8.2 µM. Using the same technique, we also determined that the farnesylated form of carboxy-terminus of the IP does not bind to PDZ1. To understand the molecular basis of these findings, we solved the high resolution crystal structure of PDZ1 bound to a 7-residue peptide derived from the carboxy-terminus of the non-farnesylated form of IP (411IAACSLC417). Analysis of the structure demonstrates a critical role for the three carboxy-terminal amino acids in establishing a strong interaction with PDZ1 and explains the inability of the farnesylated form of IP to interact with the PDZ1 domain of PDZK1 at least in vitro

Expression and regulation of the renal Na/phosphate cotransporter NaPi-IIa in a mouse model deficient for the PDZ protein PDZK1

Inorganic phosphate (Pi) is reabsorbed in the renal proximal tubule mainly via the type-IIa sodium-phosphate cotransporter (NaPi-IIa). This protein is regulated tightly by different factors, among them dietary Pi intake and parathyroid hormone (PTH). A number of PDZ-domain-containing proteins have been shown to interact with NaPi-IIa in vitro, such as Na+/H+ exchanger-3 regulatory factor-1 (NHERF1) and PDZK1. PDZK1 is highly abundant in kidney and co-localizes with NaPi-IIa in the brush border membrane of proximal tubules. Recently, a knock-out mouse model for PDZK1 (Pdzk1−/−) has been generated, allowing the role of PDZK1 in the expression and regulation of the NaPi-IIa cotransporter to be examined in in vivo and in ex vivo preparations. The localization of NaPi-IIa and other proteins interacting with PDZK1 in vitro [Na+/H+ exchanger (NHE3), chloride-formate exchanger (CFEX)/putative anion transporter-1 (PAT1), NHERF1] was not altered in Pdzk1−/− mice. The abundance of NaPi-IIa adapted to acute and chronic changes in dietary Pi intake, but steady-state levels of NaPi-IIa were reduced in Pdzk1−/− under a Pi rich diet. This was paralleled by a higher urinary fractional Pi excretion. The abundance of the anion exchanger CFEX/PAT1 (SLC26A6) was also reduced. In contrast, NHERF1 abundance increased in the brush border membrane of Pdzk1−/− mice fed a high-Pi diet. Acute regulation of NaPi-IIa by PTH in vivo and by PTH and activators of protein kinases A, C and G (PKA, PKC and PKG) in vitro (kidney slice preparation) was not altered in Pdzk1−/− mice. In conclusion, loss of PDZK1 did not result in major changes in proximal tubule function or NaPi-IIa regulation. However, under a Pi-rich diet, loss of PDZK1 reduced NaPi-IIa abundance indicating that PDZK1 may play a role in the trafficking or stability of NaPi-IIa under these condition

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Not AvailableGroundnut is one of the major oilseed crops of the tropics and subtropics, grown in an estimated area of about 25 million ha in about 90 countries with an average yield of about 1600 kg. In India, groundnut is cultivated in around 6 million ha with an annual production of around 7 million tonnes and with an average productivity of around 1270 kg/ha in rainfed situation. There is a fluctuating trend in area, production and productivity of groundnut in India. As around 90% of the crop is grown under rainfed conditions, productivity is affected due to erratic rainfall and frequent occurrence of droughts. One of the reasons of poor productivity in India is the cultivation of groundnut in marginal lands with suboptimal nutrient supply. However, being a legume crop most of its N requirement should be met from biologically fixed nitrogen. But promiscuity of groundnut allows nodulation by all the different strains of rhizobia present in the tropics and sub-tropics resulting in erratic biological nitrogen fixation. The situation is compounded further as native rhizobia often out-compete the inoculants strains. Because of insufficient biological nitrogen fixation in groundnut, very often yield is badly affected. Thus, application of highly competitive and efficiently nitrogen fixing strains of groundnut rhizobia would help in enhancing the biological nitrogen fixation vis-à-vis groundnut yield. The soils of groundnut growing areas are very often affected by acidity or alkalinity coupled with deficiency in available P, Fe, Zn, Mo, and other micronutrients. Therefore, with the application of phosphate solubilizing microorganisms, plant growth promoting rhizobacteria and other beneficial bacteria having multiple plant growth promoting traits, transformation and availability of P, Fe, Zn, Mo and other micronutrients can be improved substantially. Biofertilizers hold promise in improving the productivity of groundnut in a sustainable way, though their potential in increasing yield has not been exploited yet. With the sincere efforts of the microbiologists of the ICARDirectorate of Groundnut Research, a number of highly competitive strains of groundnut rhizobia, plant growth promoting rhizobacteria, consortia of beneficial bacteria and phosphate solubilizing bacteria have been identified and their potential demonstrated throughout the country through FLDs and demonstration. There is a need for further popularization of the biofertilizers. To provide valuable information to the farmers and extension worker about the biofertilizers of groundnut and the benefits that can be accrued from biofertilizers usage, this bulletin has been compiled. Hope this will benefit the groundnut growers of the country.Not Availabl

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Not AvailableGroundnut is cultivated in around 6 million ha with an annual production of around 7 million tonnes in India. However, the productivity remains a matter of great concern as it remains around 1250 kg/ha in rainfed situations and around 1800 kg/ha in irrigated conditions.As 90% of the crop is grown under rainfed conditions, productivity is affected by erratic and uneven distribution of rainfall, and in odd years the crop is badly affected by drought in most part of the country. In India groundnut is mostly cultivated in marginal lands , with suboptimal nutrient supply. Being a legume crop most of its N requirement should be met from biological nitrogen fixation. With an average pod yield of 2 t/ha, there is requirement of about 250 kg nitrogen. However, in rainfed and irrigated conditions, it is recommended to apply only 12.5 kg and 25 kg N/ha, respectively, and thus there is a requirement of about 200 kg of N being fixed by biological nitrogen fixation. However, groundnut is a promiscuous crop and is often nodulated by all the strains of rhizobia present in the tropics and sub-tropics. The situation is compounded further as native rhizobia often out-compete the inoculants strains. Thus, there is highly erratic biological nitrogen fixation in groundnut. Because of this, there is acute imbalance in the nitrogen availability in groundnut, thus affecting the productivity.Not Availabl

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Not AvailableA majority of the plants studied in natural ecosystems are symbiotic with microorganisms that either reside entirely (endophytes) or partially within plants. These microorganisms express different associations ranging from mutualism to parasitism. These symbiotic relationships appear to impart tolerance to various types of abiotic stresses such as heat, drought, salinity, heavy metals, etc. and sometimes may be responsible for the survival of both plant hosts and microbial symbionts in high stress habitats. The amelioration of the abiotic stresses by the endophytes assumes increasing significance in the light of rapidly changing global climate, which is likely to face frequent incidences of extreme weather conditions like high temperature, droughts, etc. To compensate the loss in crop productivity due to vagaries of nature and depleting areas of cultivable land, the application of endophytic microorganisms in agriculture is seen as a potential and ecologically sound means of maintaining profitability and sustainability in crop production. Apart from providing tolerance to abiotic stresses, majority of the endophytes are also known to confer tolerance to biotic stresses such as diseases, pests, etc. The endophytic microorganisms have also found application in remediation of heavy metal contaminated sites or polluted soils through phytoremediation. Here, we describe the role of endophytic microorganisms in alleviation of abiotic stresses in plants and the different ways by which this symbiosis can potentially mitigate the impacts of climate change and anthropogenic activities on crop plants.Not Availabl

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Not AvailableGroundnut is cultivated in around 6 million ha with an annual production of around 7 million tonnes in India. However, the productivity remains a matter of great concern as it remains around 1250 kg/ha in rainfed situations and around 1800 kg/ha in irrigated conditions.As 90% of the crop is grown under rainfed conditions, productivity is affected by erratic and uneven distribution of rainfall, and in odd years the crop is badly affected by drought in most part of the country.Not Availabl

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Not AvailableA majority of the plants studied in natural ecosystems are symbiotic with microorganisms that either reside entirely (endophytes) or partially within plants. These microorganisms express different associations ranging from mutualism to parasitism. These symbiotic relationships appear to impart tolerance to various types of abiotic stresses such as heat, drought, salinity, heavy metals, etc. and sometimes may be responsible for the survival of both plant hosts and microbial symbionts in high stress habitats. The amelioration of the abiotic stresses by the endophytes assumes increasing significance in the light of rapidly changing global climate, which is likely to face frequent incidences of extreme weather conditions like high temperature, droughts, etc. To compensate the loss in crop productivity due to vagaries of nature and depleting areas of ultivable land, the application of endophytic microorganisms in agriculture is seen as a potential and ecologically sound means of maintaining profitability and sustainability in crop production. Apart from providing tolerance to abiotic stresses, majority of the endophytes are also known to confer tolerance to biotic stresses such as diseases, pests, etc. The endophytic microorganisms have also found application in remediation of heavy metal contaminated sites or polluted soils through phytoremediation. Here, we describe the role of endophytic microorganisms in alleviation of abiotic stresses in plants and the different ways by which this symbiosis can potentially mitigate the impacts of climate change and anthropogenic activities on crop plants.Not Availabl

Not Available

Not AvailableA majority of the plants studied in natural ecosystems are symbiotic with microorganisms that either reside entirely (endophytes) or partially within plants. These microorganisms express different associations ranging from mutualism to parasitism. These symbiotic relationships appear to impart tolerance to various types of abiotic stresses such as heat, drought, salinity, heavy metals, etc. and sometimes may be responsible for the survival of both plant hosts and microbial symbionts in high stress habitats. The amelioration of the abiotic stresses by the endophytes assumes increasing significance in the light of rapidly changing global climate, which is likely to face frequent incidences of extreme weather conditions like high temperature, droughts, etc. To compensate the loss in crop productivity due to vagaries of nature and depleting areas of ultivable land, the application of endophytic microorganisms in agriculture is seen as a potential and ecologically sound means of maintaining profitability and sustainability in crop production. Apart from providing tolerance to abiotic stresses, majority of the endophytes are also known to confer tolerance to biotic stresses such as diseases, pests, etc. The endophytic microorganisms have also found application in remediation of heavy metal contaminated sites or polluted soils through phytoremediation. Here, we describe the role of endophytic microorganisms in alleviation of abiotic stresses in plants and the different ways by which this symbiosis can potentially mitigate the impacts of climate change and anthropogenic activities on crop plants.Not Availabl