Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.5.5 (CPS)
 1,262 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Citrulline, a non-protein amino acid, is present in large amounts in watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai Cucurbitaceae) fruits. Amino acid profiling of various tissues of cv. Charleston Gray during plant development confirmed progressive accumulation of citrulline only in the fruit flesh and rind tissues. Citrulline content was positively correlated with precursor (ornithine) and by-product (arginine) amino acids during fruit ripening. Genetic variation in the partitioning of citrulline and related amino acids in the flesh and rind tissues was confirmed in a sub-set of watermelon cultivars. No correlation was established between morphological fruit traits (size and rind properties) and citrulline content. To understand the regulation of citrulline accumulation, we investigated the expression of genes associated with its biosynthesis and catabolism in flesh and rind tissues during fruit development. The expression of ornithine carbamoyltransferase (OTC) involved in the ultimate step of citrulline synthesis remained steady in both tissues. The expression of N-acetylornithine aminotransferase (N-AOA) involved in the production of N-acetylornithine and N-acetylornithine deacetylase (AOD-3) involved in ornithine synthesis coincided with increasing accumulation of citrulline in flesh and rind tissues during fruit development. Down-regulation N-acetylornithine-glutamate acetyltransferase (N-AOGA) suggests the subordinate role of the non-cyclic pathway in citrulline synthesis. Eccentricity between citrulline accumulation and expression of carbamoyl phosphate synthases (CPS-1, CPS-2) during fruit development suggest that the localized synthesis of carbamoyl phosphates may not be required for citrulline synthesis. Most genes involved in citrulline break-down (Argininosuccinate synthases - ASS-1, ASS-2, and ASS-3, Argininosuccinate lyases - ASL-1, Ornithine decarboxylase - ODC, Arginine decarboxylase - ADC) were consistently down-regulated during fruit development.
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PMID:Systematized biosynthesis and catabolism regulate citrulline accumulation in watermelon. 3088 57

A non-protein amino acid, citrulline, is a compatible solute involved in the maintenance of cellular osmolarity during abiotic stresses. Despite its significance, a coherent model indicating the role of citrulline during stress conditions has not yet emerged. We have used watermelon, naturally rich in citrulline, as a model to understand its accumulation during drought stress and nitrogen perturbation using transcriptomic and metabolomic analysis. Experiments were performed in the semi-controlled environment, and open field to study the accumulation of drought-induced citrulline in the vegetative tissues of watermelon by monitoring the stress treatments using physiological measurements. The amino acid profiling of leaves and stems in response to drought stress showed up to a 38 and 16-fold increase in citrulline content, respectively. Correlation between amino acids indicated a concomitant activation of a metabolic pathway that included citrulline, its precursor (ornithine), and catabolic product (arginine). Consistent with its accumulation, the gene expression analysis and RNA-Sequencing confirmed activation of citrulline biosynthesis-related genes - Ornithine carbamoyl-transferase (OTC), N-acetylornithine deacetylase (AOD) and Carbamoyl phosphate synthases (CPS), and down-regulation of catabolic genes; Arginosuccinate lyase (ASL) and Arginosuccinate synthases (ASS) in drought-stressed leaf tissues. Based on the relative abundance in the nitrogen-depleted vegetative tissues and down-regulation of genes involved in citrulline biosynthesis, we also demonstrated that the nitrogen status of the plant regulates citrulline. Taken together, these data provide further insights into the metabolic and molecular mechanisms underlying the amino acid metabolism under environmental stress and the significance of non-protein amino acid citrulline in plants.
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PMID:Functional Relevance of Citrulline in the Vegetative Tissues of Watermelon During Abiotic Stresses. 3243 23