Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cDNA clone (MEL5), encoding a protein homologous to phytoene synthase (PSY), has been isolated from a climacteric melon fruit cDNA library, using the tomato cDNA clone TOM5 [34] as a heterologous probe. MEL5 hybridised to a transcript of 1.65 kb which suggested that the 1.36 kb clone, isolated originally, was not full-length. The missing 5' end was isolated by a reverse transcriptase-polymerase chain reaction (RT-PCR)-based method. This enabled the full sequence of the protein to be deduced and the cleavage site of the transit peptide for chromoplast import to be predicted. Northern analysis of RNA extracted from fruit samples of different ripening stages as well as from roots, leaves and flower petals was used to examine the expression pattern of the corresponding mRNA. The corresponding mRNA. The transcript corresponding to MEL5 is present at low quantities in unripe (green) fruit, reaches its highest levels when the fruit turns from green to orange and persists at lower levels during later ripening stages. A similar transcript was also detected in flower petals and in trace amounts in leaves and roots. Genomic Southern analysis indicates that the clone is homologous to a low-copy-number gene family. Sequence analysis showed a high degree of conservation among plant PSYs.
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PMID:Isolation and characterisation of a melon cDNA clone encoding phytoene synthase. 776 96

The enzyme phytoene synthase (Psy) catalyzes the formation of phytoene, an intermediate in the carotenoid biosynthesis pathway. Expression of a previously described gene (PSY1) is induced by fruit ripening in tomato (Lycopersicon esculentum). We describe here the cloning of a partial cDNA for PSY2, a gene related to PSY1. A plasmid containing the PSY2 coding region under control of a bacterial promoter complements a Rhodobacter capsulatus phytoene synthase mutant, indicating that this gene has the capacity to encode an active enzyme. We used reverse transcriptase-polymerase chain reaction followed by digestion with a restriction enzyme to determine that both PSY1 and PSY2 are expressed during tomato development. PSY1 transcripts predominate in seedlings and in late stages of fruit ripening, whereas PSY2 transcripts are relatively more abundant in mature leaves. Both genes are expressed under photooxidative conditions induced by treatment with the carotenoid biosynthesis inhibitor Norflurazon. We used polymerase chain reaction-based restriction fragment length polymorphisms and alien addition lines to map PSY2 to chromosome 2. We conclude that PSY2 is a second tomato gene encoding phytoene synthase.
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PMID:cDNA cloning, expression during development, and genome mapping of PSY2, a second tomato gene encoding phytoene synthase. 824 8

Dietary micronutrient deficiencies, such as the lack of vitamin A, are a major source of morbidity and mortality worldwide. Carotenoids in food can function as provitamin A in humans, while grains of Chinese elite wheat cultivars generally have low carotenoid contents. To increase the carotenoid contents in common wheat endosperm, transgenic wheat has been generated by expressing the maize y1 gene encoding phytoene synthase driven by a endosperm-specific 1Dx5 promoter in the elite wheat (Triticum aestivum L.) variety EM12, together with the bacterial phytoene desaturase crtI gene from Erwinia uredovora under the constitutive CaMV 35S promoter control. A clear increase of the carotenoid content was detected in the endosperms of transgenic wheat that visually showed a light yellow color. The total carotenoids content was increased up to 10.8-fold as compared with the nontransgenic EM12 cultivar. To test whether the variability of total carotenoid content in different transgenic lines was due to differences in the transgene copy number or expression pattern, Southern hybridization and semiquantitative reverse transcriptase polymerase chain reaction analyses were curried out. The results showed that transgene copy numbers and transcript levels did not associate well with carotenoid contents. The expression patterns of endogenous carotenoid genes, such as the phytoene synthases and carotene desaturases, were also investigated in wild-type and transgenic wheat lines. No significant changes in expression levels of these genes were detected in the transgenic endosperms, indicating that the increase in carotenoid transgenic wheat endosperms resulted from the expression of transgenes.
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PMID:Expression of phytoene synthase1 and carotene desaturase crtI genes result in an increase in the total carotenoids content in transgenic elite wheat (Triticum aestivum L.). 1969 33